Re: atomic test and set
> On Oct 17, 2017, at 5:40 PM, Tobin C. Harding wrote:
>
> Hi,
>
> Do we have an atomic test and set function in the kernel. I have tried
Yes and it is used very much inside the kernel.
>
> const int KEY_FLAG_BIT = 1;
>
> ...
>
>static siphash_key_t ptr_secret __read_mostly;
>static unsigned long have_key = 0;
>
>if (test_and_set_bit(KEY_FLAG_BIT, &have_key))
>get_random_bytes(&ptr_secret, sizeof(ptr_secret));
>
>
> But that doesn't work.
What doesn't work? What you expected and how is the result different?
>
> I looked in include/linux/atomic.h and thought about using
>
>static atomic_t have_key = ATOMIC_INIT(0);
>
>if (atomic_xchg(&have_key, 1) == 0)
>get_random_bytes(&ptr_secret, sizeof(ptr_secret));
>
>
> This works. My question is; does this code LOAD the value at have_key and
> STORE the argument on
> every call? Or does it LOAD the value, check if it is the same as the
> argument, and STORE _only_ if
> it is different?
Did you read this https://www.mjmwired.net/kernel/Documentation/atomic_ops.txt ?
> (Is this whole discussion just premature optimization?)
This has nothing to do with optimization but rather the requirement. In kernel
atomic variables are used to avoid race conditions generally.
>
> I cannot grok the macros in atomic.h, they seem circular. Here is the macro
> definitions in call
> chain order starting with atomic_xchg()
Implementation would differ based on the architecture. In some architectures it
would be a single instruction and in others it may not be the case.
>
>
> #define atomic_xchg(...)\
>__atomic_op_fence(atomic_xchg, __VA_ARGS__)
>
> #define __atomic_op_fence(op, args...)\
> ({\
>typeof(op##_relaxed(args)) __ret;\
>smp_mb__before_atomic();\
>__ret = op##_relaxed(args);\
>smp_mb__after_atomic();\
>__ret;\
> })
>
> #define atomic_xchg_release(...)\
>__atomic_op_release(atomic_xchg, __VA_ARGS__)
>
> #define __atomic_op_release(op, args...)\
> ({\
>smp_mb__before_atomic();\
>op##_relaxed(args);\
> })
>
> #define atomic_xchg_relaxedatomic_xchg
>
> thanks,
> Tobin.
>
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Re: Help on modelling gpio interrupt source when interrupt is shared
> On Jan 23, 2017, at 10:56 PM, Rajasekhar Pulluru
> wrote:
>
> Hi Anish,
>
> My intention is just to detect interrupt in the user space and read the
> device id without using udev.
>
> I don't want to create a new driver in kernel (assume I can't modify linux
> kernel sources), which is the first reason to go for uio generic platform
> driver.
>
> If I register a gpio interrupt (level triggered) using a kernel module, I can
> get the interrupt detected
Which means you are able to do insmod, so you can very well write a kernel
module and send some event to user space.
> when device is inserted/removed. But I would like to detect device presence
> completely from user space without modifying linux kernel.
>
> Thanks & Regards,
> Rajasekhar
>
>> On Tue, Jan 24, 2017 at 11:56 AM, anish singh
>> wrote:
>>
>>
>>> On Mon, Jan 23, 2017 at 7:46 AM, Rajasekhar Pulluru
>>> wrote:
>>> Hi,
>>>
>>> I have a query on device tree pertaining to modelling a gpio pin as an
>>> interrupt source.
>>> I have searched mailing list archives and kernel documentation before
>>> posting this and couldn't get any direct solution.
>>> (My understanding is limited and hence posting the query below:)
>>>
>>> My SOC has a gpio controller and uart both sharing same interrupt line as
>>> specified below.
>>>
>>> interrupt-parent = <&gic>;
>>>
>>> mygpio: gpio@0x19008000 {
>>> compatible = "mysoc,mygpio-controller,gc";
>>> #address-cells = <1>;
>>> #size-cells = <1>;
>>> #gpio-cells = <2>;
>>> reg = gpio: <0x19008000 0x50>;
>>> ngpios = <12>;
>>> pin-offset = <4>;
>>> pin-base = <4>;
>>> irq-base = <256>; /* sw irq base for irq handlers */
>>> gpio-controller;
>>> interrupt-controller;
>>> interrupts = ;
>>> };
>>>
>>> uart0: serial@0x19000300 {
>>> compatible = "snps,dw-apb-uart";
>>> reg = <0x19000300 0x100>;
>>> interrupts = ;
>>> clock-frequency = <6250>;
>>> };
>>>
>>> gpio pin 0 of mygpio is used as an interrupt source for detecting the
>>> presence of external pluggable device (that is not driven by kernel).
>>> And I intend to detect the presence of the pluggable device from user space
>>> by means of generic uio platform driver using below device
>>
>> What do you intend to achieve by detecting device in userspace?
>> You can directly get notification using udev notification.
>>
>> However, you need to send udev notification from a kernel driver.
>>
>>> tree configuration. (following
>>> https://yurovsky.github.io/2014/10/10/linux-uio-gpio-interrupt/)
>>>
>>> user_io@0 {
>>> compatible = "mydevice,generic-uio,ui_pdrv";
>>> status = "okay";
>>> interrupt-parent = <&mygpio>;
>>> interrupts = <0 IRQ_TYPE_LEVEL_HIGH>;
>>> };
>>>
>>> Running modprobe uio_pdrv_genirq of_id="mydevice,generic-uio,ui_pdrv" and
>>> creating /dev/uio0 using mknod (major number from cat /proc/devices | grep
>>> uio),
>>> I couldn't see an irq entry bind to uio driver under /proc/interrupts.
>>> Am I doing anything wrong here?
>>>
>>> Other method I have tried to get notified of the gpio pin0 interrupt in
>>> user space is to poll on /sys/class/gpio/gpio0/value. But merely exporting
>>> gpio0
>>> wasn't sufficient as kernel should make a call to request_irq on the gpio0
>>> interrupt line. Is there a generic driver framework (like pinctrl) that can
>>> export
>>> a device node to register the gpio pin0 as an interrupt source that allows
>>> me to poll on its sysfs entry?
>>
>> All sysfs nodes can be polled as it is supported in kernel.
>> You can simply create a dummy driver and register the
>> irq and in your irq handler send udev notifications using
>> kobj.
>>
>> Or
>> just update a sysfs node which can be polled from userspace.
>>
>> If this answer is not sufficient then please explain in detail
>> what you are planning to achieve rather than what you are
>> doing to achieve that.
>>>
>>> Thanks,
>>> Rajasekhar
>>>
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>>>
>>
>
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Re: adding 32 bit compatibility layer in custom kernel module
> On Jan 3, 2017, at 10:03 PM, Pradeepa Kumar wrote: > > Please see inline below > >> On Wed, Jan 4, 2017 at 11:07 AM, Anish Kumar >> wrote: >> >> >>> On Jan 3, 2017, at 8:04 PM, Pradeepa Kumar wrote: >>> >>> Hi experts >>> >>> down vote >>> favorite >>> in my 64 bit kernel, I have a custom kernel module providing new protocol >>> and providing socket system calls. >>> >>> it works fine when 64 bit app runs. >>> >>> i am seeing issues when 32 bit app runs (for exp recvmsg() call does not >>> work if msg has cmsghdrs as struct size of cmsghdr is different in 32 bit >>> and 64 bit). >>> >>> This is because my custom kernel module does not have 32 bit compatibility >>> layer ( but linux kernel has this in compat.c etc). >>> >>> is it simple to add compatibility layer to my custom kernel module >>> >>> All you have to do is add compat_ioctl call to your driver. > my kernel module provides recvmsg() but i dont see any 'compat_recvmsg' in > struct proto_ops. Try to wrap your text in 80 characters. Your application is crashing? Right? Have you figured where it is crashing exactly? I understood that your application is crashing as It not able to function with 64 bit kernel. This happens because of the data being passed to kernel is not in the right format. You need to look at what you are passing to the driver and if needed write the compat_ioctl callback in your driver fops. > had there been 'compat_recvmsg' it would have been possible for me to define > recvmsg() for 32 bit apps. > please let me know if i am missing anything > >>> how do i do this (any links ?) >>> >>> You can see many drivers supports compat call. >>> Thanks >>> >>> ___ >>> Kernelnewbies mailing list >>> Kernelnewbies@kernelnewbies.org >>> https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: adding 32 bit compatibility layer in custom kernel module
> On Jan 3, 2017, at 8:04 PM, Pradeepa Kumar wrote: > > Hi experts > > down vote > favorite > in my 64 bit kernel, I have a custom kernel module providing new protocol and > providing socket system calls. > > it works fine when 64 bit app runs. > > i am seeing issues when 32 bit app runs (for exp recvmsg() call does not work > if msg has cmsghdrs as struct size of cmsghdr is different in 32 bit and 64 > bit). > > This is because my custom kernel module does not have 32 bit compatibility > layer ( but linux kernel has this in compat.c etc). > > is it simple to add compatibility layer to my custom kernel module > > All you have to do is add compat_ioctl call to your driver. > how do i do this (any links ?) > > You can see many drivers supports compat call. > Thanks > > ___ > Kernelnewbies mailing list > Kernelnewbies@kernelnewbies.org > https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Options for adding I2C devices and how-to
> On Sep 30, 2016, at 6:23 PM, vibnwis wrote: > > Hi there, > > My questions are about the options available for adding I2C devices onto > existing single board computers, such as Panda Board or Raspberry Pi. Later > then I would ask how to get it done. > > By far, I have found out the following options. Correct me if I am wrong as > my understanding s still hazy. > > 1. BitBanging method. That is by connecting it to existing unused GPIOs. > Need to create a Bitbanging client driver for the device with the two GPIOs > for SDA, SCLK respectively Right > > 2. Use existing allocated I2C Pins. Assuming the kernel driver for the device > is already available, then simply run make menuconfig to configure to use the > right I2c device. However, if the driver is not available. One needs to > create a new client driver. if up to now I am still not wrong, then I have a > few questions. >a) what address is it and how to specify one for the new device? would > like wise to use the existing allocated addresses which are not being used > due to non-existence of those I2C devices on the system? You need to find out the device address of your device. find out which device is not connected and connect your device on that bus and change the device tree to replace the device address. > b) if somehow, the new I2C device has somewhat similar architecture > with the existing supporter I2C devices, would it wise to use it instead of > developing a new client driver? I am trying to say that would it wise to > trial and error some of the existing supporting driver if they are > compatible. Only after testing then decide if new driver development is > needed. Is it the right thing to do? You mean if the regmap is similar? I don't think that would be the case unless both devices are from the same company with minor revision change. > > 3. Writing/using user mode I2c driver. You can certainly use i2c_detect and i2c_get user space tools to work with your device. However is there is a existing kernel space i2c device on that bus then it will certain lead to bus hogging problems. > > Feel free to add any comments or suggestions. Please add information about your device and kernel version which you are trying to use. May be there is already a driver for it in open source. Best of luck!! > > Thank you in advance. > > Best regards, > Lim > > > ___ > Kernelnewbies mailing list > Kernelnewbies@kernelnewbies.org > https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: gpio-led driver
> On Jul 20, 2016, at 4:15 AM, Raul Piper wrote: > > Hi, > I wanted to know the part number What is part number? > for the leds-gpio.c in the driver/leds folder and the device tree bindings > for this driver .Can some one point out to me where in Linux kernel it is? > > Also why below line has been used.Is it mandatory? > ... > .of_match_table = of_gpio_leds_match, This is needed when you are using device tree for getting the board settings but you can also do the same without this as well. Read up on device tree in kernel Documentation folder. > }, > > thanks in advance , > Rp > ___ > Kernelnewbies mailing list > Kernelnewbies@kernelnewbies.org > https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: I have a large patch in the 2000 lines. What to do?
> On Oct 9, 2015, at 11:45 AM, Ivan Safonov wrote: > > Hi! > > I have a large patch in the 2000 lines, which replaces the macro BITn to > BIT(n) in multiple files. I will recommend sending RFC patch first and Get the community comments. If they like your patch then divide the patch based on logic rather than lines of codes. > Is it worth to split this patch into several parts? > Is it sufficient to place the changes in each file in a separate part of > patchset? > > > > ___ > Kernelnewbies mailing list > Kernelnewbies@kernelnewbies.org > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: bitops for handling 32 bits
> On Jul 28, 2015, at 10:46 PM, Kevin Wilson wrote: > > Hi all, > Is there a kernel API for handling 32 bits ? > I see a macro like BIT(nr) > http://lxr.free-electrons.com/source/include/linux/bitops.h#L6 > > #define BIT(nr) (1UL << (nr)) > > and also > #define BIT_ULL(nr) (1ULL << (nr)) > > However, these macros are using 64 bit semantics, so if I will use > them with 32 bits values > the results will be wrong. Did you try using it? The code is generic. > > Any ideas ? > > Regards, > Kevin > > ___ > Kernelnewbies mailing list > Kernelnewbies@kernelnewbies.org > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: why use while(0) to write set_current_state
> On Jun 16, 2015, at 10:01 PM, 慕冬亮 wrote:
>
> I see the macro in the include/linux/sched.h
> #define __set_current_state(state_value) \
> do { current->state = (state_value); } while (0)
>
> Why define it like this? What's the meaning of while?
Read this and you will know why.
http://kernelnewbies.org/FAQ/DoWhile0
> mudongliang
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Re: To use wake_up_interruptible in ISR
> On May 25, 2015, at 10:02 PM, 김찬 wrote: > > Hello, > > I see in the source (linux ver 3.3) that wake_up_interruptible function > doesn't sleep so I used in it an ISR but I'm getting 'BUG:scheduling while > atomic' message. (I'm not sure it's coming from this) Remove it and check if the problem goes away. > I'm looking for the exact cause but Is there any caveat when using > wake_up_interruptible() in an ISR? (I found some drivers use it in ISR, some > use it in work_struct) > I think there should be no problem using this api in isr context. > I also read in > http://www.slideshare.net/rampalliraj/tasklet-vs-work-queues?from_action=save > that tasklet is not allowed to sleep but work is. (because tasklet is not > in process context, but in bottom-half) > I don't know if I have to move the wake_up_interruptible function to tasklet > or work(queue) or even it matters to the current problem. > > Any help would be greatly appreciated. What are you trying to achieve. > Regards, > > Chan > > ___ > Kernelnewbies mailing list > Kernelnewbies@kernelnewbies.org > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: getting interrupt number
> On Mar 8, 2015, at 7:25 PM, Ronit Halder wrote: > > How to get the interrupt number of a device.I know it's device id and > the bus number. > The device is a usb mouse. Interrupt number is not a constant value. Depending on the board it changes. For which are you asking ? > > ___ > Kernelnewbies mailing list > Kernelnewbies@kernelnewbies.org > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Get local CPU id
You can use ftrace and such. > On Mar 8, 2015, at 12:06 PM, Matwey V. Kornilov > wrote: > > Hi, > > I would like to somehow obtain local CPU core ID in the interrupt > handler function. I want to see how my interruptions are distributed > among different CPU cores under different conditions. > > How should I do that? > > > ___ > Kernelnewbies mailing list > Kernelnewbies@kernelnewbies.org > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: workqueues - how to use them correctly
> On Feb 10, 2015, at 12:50 AM, Roshan A wrote: > > hi all, > > My question is regarding the correct use of workqueues. I have a > driver which queues a work item in the interrupt handler. The bottom > half function ( the workitem -function ) does have proper locking ( > mutex ) in place for atomicity. Post the code snippet and why are you using Mutex? If you want to synchronize between Interrupt handler and workqueue then you should use spinlocks. > > With this setup, since the interrupts are enabled, it's possible to > have a scenario where, when one workitem is being executed, another > can be queued up, which results in the workitems being executed in > parallel, however since there is a mutex, one thread will sleep. And precisely the reason not to use mutex locks. > > is this particular scenario considered bad or discouraged ? Now what do you think? > > Thank you, > -Roshan > > ___ > Kernelnewbies mailing list > Kernelnewbies@kernelnewbies.org > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: container_of
> On Jan 17, 2015, at 8:32 AM, Simon Brand wrote:
>
> Good evening,
>
> i read the article about the container_of function:
> http://www.kroah.com/log/linux/container_of.html
>
> I understand what it does and how it works.
>
> I thought, it could be simplified by replacing it through this:
>
> #define container_of(ptr, type, member) ({ \
>(type *)( (char *)ptr - offsetof(type,member) );})
>
> Original:
> #define container_of(ptr, type, member) ({ \
>const typeof( ((type *)0)->member ) *__mptr = (ptr);
>(type *)( (char *)__mptr - offsetof(type,member) );})
>
>
> ptr has the type of a pointer to the member, which should be the same
> as __mptr? The value should although be the same.
>
> First I tried it in a self written script, then replaced it in
> include/linux/kernel.h and compiled it as usermode linux -> working
> well.
>
> Then I compiled it and run it in a VM, but it is not working.
What do you mean by that? What is not working?
>
> Can you please explain to me, why the original version is always working
> and "mine" is not?
>
> Thank you for your time!
>
> Regards,
> Simon
>
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Re: scheduler help
I am sure you can get help in Linux mailing list as kernel newbies list would not be be able to answer this.I think there is specific scheduler mailing list. > On Dec 8, 2014, at 5:48 AM, alexis wrote: > > hello to everyone , > l have a assignment and i need help. > i have to change the scheduler function at kernel 2.6.38 so that the > scheduler choose the process > with the least slack time. > > My problem : > i have create a function that iterates all runnable processes finds the > one with least slack time(lst) > and returns a pointer to the task( struct task_struct*) > Now i need to change the scheduler so that selected for execution the > process with lst. > > i am trying to change the function pick_next_task_fair in file sched_fair.c > but i cant understand the code in there can someone explain me ? > > is the pick_next_task_fair the right function that need change? > if yes it is the only one ? > > sorry for my English > thanks. > > > ___ > Kernelnewbies mailing list > Kernelnewbies@kernelnewbies.org > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: test jiffies on ARM SMP board
On Wed, 2013-02-20 at 17:30 +, Russell King - ARM Linux wrote:
> On Wed, Feb 20, 2013 at 10:54:41PM +0530, anish kumar wrote:
> > On Thu, 2013-02-21 at 00:39 +0800, buyitian wrote:
> > > i am confused about my test. in one device driver,
> > > i put below code:
> > >
> > > printk("start to test test jiffies\n");
> > >
> > > local_irq_save(flags);
> > >
> > > jf1 = jiffies; // read jiffies first time
> > >
> > > // hold cpu for about 2 seconds(do some calculation)
> > >
> > > jf2 = jiffies; // read jiffies after 2 seconds
> > >
> > > local_irq_restore(flags);
> > >
> > > printk("jf1:%lu, jf2:%lu\n", jf1, jf2);
> > >
> > > and the output is as below:
> > >
> > > <4>[ 108.551124]start to test test jiffies
> > > <4>[ 110.367604]jf1:4294948151, jf2:4294948151
> > >
> > > the jf1 and jf2 are the same value, although they are
> > > read between 2 seconds interval, i think this is because
> > > i disabled local interrupt.
> > > but the printk timestamp is from 108.551124 to 110.367604,
> > > which is about 2 seconds. and on my platform, printk timestamp
> > > is got from the function read_sched_clock:
> > >static u32 __read_mostly (*read_sched_clock)(void) =
> > > jiffy_sched_clock_read;
> > >
> > > and function jiffy_sched_clock_read() is to read from jiffies.
> > >
> > > it seems that the jiffies is frozen when local irq is disabled,
> > > but after local_irq_restore(), the jiffies not only start
> > > to run, but also recover the lost 2 seconds.
> > >
> > > is the jiffies updated from another cpu when irq is disabled on
> > > local cpu?
> > >
> > > is there some internel processor interrupt between cpu1 and cpu0
> > > after local irq is re-enabled so that jiffies recover the lost 2 seconds?
> > >
> > I think it is because of the fact that some RTC registers keep the
>
> The RTC has nothing to do with this.
>
> As soon as the IRQs are allowed again (immediately after the
> local_irq_restore()) the pending interrupt - including the timer
> interrupt will be processed.
>
> At this point, because we read the clocksource, we can see that two
> seconds have passed, and so we advance jiffies by the elapsed time.
So I understand there is some register which stores the elapsed time and
in my understanding it was RTC register which is wrong as suggested by
you.I suppose some timer register is used for this information on the
SOC.
>
> This means printk() sees that the two seconds have passed. But because
> you're reading from jiffies within the interrupt disabled region, that
> code can't see the missed ticks.
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Re: test jiffies on ARM SMP board
On Thu, 2013-02-21 at 00:39 +0800, buyitian wrote:
> i am confused about my test. in one device driver,
> i put below code:
>
> printk("start to test test jiffies\n");
>
> local_irq_save(flags);
>
> jf1 = jiffies; // read jiffies first time
>
> // hold cpu for about 2 seconds(do some calculation)
>
> jf2 = jiffies; // read jiffies after 2 seconds
>
> local_irq_restore(flags);
>
> printk("jf1:%lu, jf2:%lu\n", jf1, jf2);
>
> and the output is as below:
>
> <4>[ 108.551124]start to test test jiffies
> <4>[ 110.367604]jf1:4294948151, jf2:4294948151
>
> the jf1 and jf2 are the same value, although they are
> read between 2 seconds interval, i think this is because
> i disabled local interrupt.
> but the printk timestamp is from 108.551124 to 110.367604,
> which is about 2 seconds. and on my platform, printk timestamp
> is got from the function read_sched_clock:
>static u32 __read_mostly (*read_sched_clock)(void) =
> jiffy_sched_clock_read;
>
> and function jiffy_sched_clock_read() is to read from jiffies.
>
> it seems that the jiffies is frozen when local irq is disabled,
> but after local_irq_restore(), the jiffies not only start
> to run, but also recover the lost 2 seconds.
>
> is the jiffies updated from another cpu when irq is disabled on
> local cpu?
>
> is there some internel processor interrupt between cpu1 and cpu0
> after local irq is re-enabled so that jiffies recover the lost 2 seconds?
>
I think it is because of the fact that some RTC registers keep the
elapsed time and when the irq is re-enabled the kernel reads these
registers to be in sync with time.
However I am not that sure which registers as I think that depends on
the RTC chip and chip changes based on different boards.
I hope some expert on these matters can pitch in here.
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Re: process 0 ("swapper")
On Sat, 2013-02-16 at 18:48 +0200, Kevin Wilson wrote:
> Hi,
>
> > we see this code in proc_pid_lookup:
> >
> > tgid = name_to_int(dentry);
> > if (tgid == ~0U)
> > goto out;
It is the error case when name can't be converted to integer i.e.
name is wrong.
> >
> > In other words, if you ask for pid 0, it bails and doesn't return anything.
>
> Are you sure that this is what it cjecks?
>
> ~0U is not 0 but -1;
right
>
> for example, try:
> printf("%d\n",~0U );
> printf("%x\n",~0U );
> printf("%x\n",-1 );
> and you get:
> -1
>
>
> rgs
> Kevin
>
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Re: spinlock deadlock
On Sat, 2013-02-16 at 00:34 +0800, buyitian wrote: > I am looking at version 3.4 > > 在 2013-2-16，0:17，valdis.kletni...@vt.edu 写道： > > > On Fri, 15 Feb 2013 17:17:38 +0530, anish singh said: > >> adding Joe Perches as generally he looks after printk stuff. > >> > >> On Fri, Feb 15, 2013 at 2:22 PM, buyitian wrote: > >>> is it possible that printk cause deadlock? the path is as below: > >>> > >>> 1. taskA runs on CPU0, and run schedule to acqire the rq->lock. > >>> 2. taskA calls printk while holding rq->lock. > >>> 3. taskA holds console_sem. > >>> 4. taskB runs on CPU1, and call console_lock(), which is blocked by > >>> console_sem and queue itslef to the wait list. > >>> 5. taskB migrates from CPU1 to cpu0. will this step occur? > >>> 6. taskA calls up(&console_sem)--> > >>> wake_up_process()-->try_to_wake_up()-->ttwu_queue()-->raw_spin_lock(&rq->lock). > >>> here taskA tries to acquire the rq->lock of CPU0 again. > > > > I'm not Joe, but what kernel release are you looking at? ISTR that in > > the last few releases (3.5-ish maybe?), that code got overhauled to > > prevent a similar issue.. Can you ask this question in kernel maling list?I think you might get a better reply to your queries. > > ___ > > Kernelnewbies mailing list > > Kernelnewbies@kernelnewbies.org > > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Kernel code interrupted by Timer
On Sun, 2013-02-10 at 00:47 +0800, Peter Teoh wrote: > > > On Sun, Feb 10, 2013 at 12:22 AM, Frederic Weisbecker > wrote: > 2013/2/9 Peter Teoh : > > A search in the entire subtree of arch/x86/ and including > all its > > subdirectories, (for 3.2.0 kernel) return only TWO result > where > > preempt_schedule_irq is called: kernel/entry_64.S and > kernel/entry_32.S. > > And the called is in fact resume_kernel(), ie, it is NOT > called from timer > > interrupt, but from wakeup context of the CPU, and is only > executed ONCE > > upon waking up from hibernation. > > > > for example, calling from here: > > > > https://lkml.org/lkml/2012/5/2/298 > > > > so definitely this preempt_schedule_irq() calling from irq > mode is rare - at > > least for x86. > > > The name "resume_kernel" can indeed sound like something that > is > called on hibernation resume. It's actually not related at > all. It's a > piece of code that is called at the end of every irq and > exception > when the interrupted code was running in the kernel. If the > interrupted code was running in userspace, we jump to > resume_userspace. > > well, i guessed u must be the expert here, i have yet to really digest > all these...:-). thanks for the explanation. In the kernel folder do this: git log --author="Frederic Weisbecker" > > > -- > Regards, > Peter Teoh ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Kernel code interrupted by Timer
Thanks Frederic.
On Sat, 2013-02-09 at 08:44 +0100, Frederic Weisbecker wrote:
> 2013/2/8 Gaurav Jain :
> > What happens if the kernel executing in some process context (let's say
> > executing a time-consuming syscall) gets interrupted by the Timer - which is
> > apparently allowed in 2.6 onwards kernels.
> >
> > My understanding is that once the interrupt handler is done executing, we
> > should switch back to where the kernel code was executing.
>
> Exactly. At the end of the interrupt, the state of the processor
> (register values) as it was before being interrupted is restored.
>
> > Specifically, the
> > interrupt handler for the Timer interrupt should not schedule some other
> > task since that might leave kernel data in an inconsistent state - kernel
> > didn't finish doing whatever it was doing when interrupted.
> >
> > So, does the Timer interrupt handler include such a policy for the above
> > case?
>
> In the case you have CONFIG_PREEMPT and it's the turn for some other
> task to be scheduled, the function preempt_schedule_irq() is called
> right before the irq return to the interrupted code. If the irq
> interrupted preemptible code (code that was not under a
> preempt_disable() section) then the scheduler may well schedule
> another task.
However if the code is under preempt_disable() when irq happened then it
won't choose any other task and will come back immediately to the task
which was preempted by the irq handler.
I think what you are referring is below code:
__irq_svc:
svc_entry
irq_handler
#ifdef CONFIG_PREEMPT
get_thread_info tsk
ldr r8, [tsk, #TI_PREEMPT] @ get preempt count
ldr r0, [tsk, #TI_FLAGS]@ get flags
teq r8, #0 @ if preempt count != 0
movne r0, #0 @ force flags to 0
tst r0, #_TIF_NEED_RESCHED
blnesvc_preempt
#endif
#ifdef CONFIG_PREEMPT
svc_preempt:
mov r8, lr
1: bl preempt_schedule_irq@ irq en/disable is done
inside
ldr r0, [tsk, #TI_FLAGS]@ get new tasks TI_FLAGS
tst r0, #_TIF_NEED_RESCHED
moveq pc, r8 @ go again
b 1b
#endif
/*
* this is the entry point to schedule() from kernel preemption
* off of irq context.
* Note, that this is called and return with irqs disabled. This will
* protect us against recursive calling from irq.
*/
asmlinkage void __sched preempt_schedule_irq(void)
{
struct thread_info *ti = current_thread_info();
/* Catch callers which need to be fixed */
BUG_ON(ti->preempt_count || !irqs_disabled());
user_exit();
do {
add_preempt_count(PREEMPT_ACTIVE);
local_irq_enable();
__schedule();
local_irq_disable();
sub_preempt_count(PREEMPT_ACTIVE);
/*
* Check again in case we missed a preemption
opportunity
* between schedule and now.
*/
barrier();
} while (need_resched());
}
>
> It may indeed sound suprising that we schedule from an interrupt but
It is really *surprising* that we do scheduling from interrupt context.
Doesn't Do's and Don't of scheduling from interrupt context apply here?
So how does the regular call to schedule() occur when task(process) time
slice is over?
> it's actually fine. Later on, the scheduler restores the previous task
> to the middle of preempt_schedule_irq() and the irq completes its
Sorry didn't understand this sentence i.e. "scheduler restores the
previous task to the middle of preempt_schedule_irq()".
> return to what it interrupted. The state of the processor prior to the
> interrupt is stored on the task stack. So we can restore that anytime.
> Note if the irq interrupted userspace, it can do about the same thing,
> except it calls schedule() directly instead of preempt_schedule_irq().
>
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Re: Kernel code interrupted by Timer
On Sat, 2013-02-09 at 14:57 +0800, Peter Teoh wrote: > > > On Sat, Feb 9, 2013 at 1:47 PM, anish kumar > . > Timer interrupts is supposed to cause scheduling and scheduler > may or > may not pick up your last process(we always use the term > "task" in > kernel space) after handling timer interrupt. > > > > > > Sorry if I may disagree, correct me if wrong. Timer interrupt and > scheduler is two different thing. I just counted in the "drivers" > subdirectory, there are at least more than 200 places where > "setup_timer()" is called, and these have nothing to do with > scheduling. For eg, heartbeat operation etc. Not sure I > misunderstood something? Have a look at kernel/timer.c and kernel/hrtimer.c. There are many sched() calls in these files.This will invoke scheduler. > > > -- > Regards, > Peter Teoh ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Kernel code interrupted by Timer
On Fri, 2013-02-08 at 18:08 +0100, Gaurav Jain wrote: > What happens if the kernel executing in some process context (let's > say executing a time-consuming syscall) gets interrupted by the Timer > - which is apparently allowed in 2.6 onwards kernels. > > > My understanding is that once the interrupt handler is done executing, > we should switch back to where the kernel code was executing. *Should* doesn't mean immediately. > Specifically, the interrupt handler for the Timer interrupt should > not schedule some other task since that might leave kernel data in an > inconsistent state - kernel didn't finish doing whatever it was doing > when interrupted. Timer interrupts is supposed to cause scheduling and scheduler may or may not pick up your last process(we always use the term "task" in kernel space) after handling timer interrupt. > > > So, does the Timer interrupt handler include such a policy for the > above case? what do you mean? > > > > -- > Gaurav Jain > > > > > > ___ > Kernelnewbies mailing list > Kernelnewbies@kernelnewbies.org > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: pr_info not printing message in /var/log/messages
On Tue, 2013-02-05 at 16:18 -0500, valdis.kletni...@vt.edu wrote:
> On Wed, 06 Feb 2013 04:43:20 +0800, Jimmy Pan said:
>
> > in fact, i've been always wondering what is the relationship between dmesg
> > and /var/log/message. they diverse a lot...
dmesg is provided by kernel using cat /proc/kmsg.
/proc/kmsg is like any other linux file which supports below file
operations:
from /kernel/printk.c
const struct file_operations kmsg_fops = {
.open = devkmsg_open,
.read = devkmsg_read,
.aio_write = devkmsg_writev,
.llseek = devkmsg_llseek,
.poll = devkmsg_poll,
.release = devkmsg_release,
};
printk dumps it's output in the ring buffer whose size is set using
defconfig CONFIG_LOG_BUF_SHIFT(if 16 => then ring buffer size is 64KB,
and for 17 => 128KB).
This ring buffer is the source for syslog and klogd daemon logs.How it
extracts the buffer depends on the configuration of these deamons.
Call stack:
printk
vprintk_emit
log_store
write to log_buf
log_from_idx used by /proc/kmsg to read the buffer
sylog uses ioctl to work on ring buffers:
case SYSLOG_ACTION_CLOSE: /* Close log */
case SYSLOG_ACTION_OPEN:/* Open log */
case SYSLOG_ACTION_READ:/* Read from log */
case SYSLOG_ACTION_READ_CLEAR:
case SYSLOG_ACTION_READ_ALL:
case SYSLOG_ACTION_CLEAR:
case SYSLOG_ACTION_CONSOLE_OFF:
case SYSLOG_ACTION_CONSOLE_ON:
case SYSLOG_ACTION_CONSOLE_LEVEL:
case SYSLOG_ACTION_SIZE_UNREAD:
case SYSLOG_ACTION_SIZE_BUFFER:
Quoting from
http://askubuntu.com/questions/26237/difference-between-var-log-messages-var-log-syslog-and-var-log-kern-log
Syslog is a standard logging facility. It collects messages of various
programs and services including the kernel, and stores them, depending
on setup, in a bunch of log files typically under /var/log. There are
also possibilities to send the messages to another host over network, to
a serial console, to a database table, etc.
According to my /etc/syslog.conf, default /var/log/kern.log captures
only the kernel's messages of any loglevel; i.e. the output of dmesg.
/var/log/messages instead aims at storing valuable, non-debug and
non-critical messages. This log should be considered the "general system
activity" log.
/var/log/syslog in turn logs everything, except auth related messages.
Other insteresting standard logs managed by syslog
are /var/log/auth.log, /var/log/mail.log.
Regarding your question: if you need solely kernel messages log, use the
kern.log or call dmesg.
>
> What ends up in /var/log/message is some subset (possibly 100%, possibly 0%)
> of what's in dmesg. Where your syslog daemon routes stuff is a local config
> issue - if your syslogd supports it, there's no reason not to dump the
> iptables
> messages in to /var/log/firewall and the rest of it in /var/log/kernel, or
> any other policy that makes sense for the sysadmin
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Re: locking spinlocks during copy_to_user, copy_from_user
On Fri, 2013-01-25 at 10:00 -0300, Pablo Pessolani wrote:
> Hi:
>It is well know that is not recomended to keep a spinlock locked
> during operations that can be preempted. Some of these operations are
> copy_to_user, copy_from_user.
> Below is the code of the write_lock() as a sample.
>
> 340 static inline void __write_lock(rwlock_t *lock)
> 341{
> 342preempt_disable(); << THE ISSUE IS HERE <<
> 343rwlock_acquire(&lock->dep_map, 0, 0, _RET_IP_);
> 344LOCK_CONTENDED(lock, _raw_write_trylock, _raw_write_lock);
> 345}
>
> On write_unlock() the preemtion is enable.
>
> My question is: Is there any know consequence if I enable preemption
> before copy_to_user/copy_from user (keeping the spinlock locked) and
why do you want to do this?
> then disable preemption again after the copy?
> i.e.:
> write_lock(&lock);
> ...
> preempt_enable();
> copy_to_user(...);
> preempt_disable();
> ...
> write_unlock(&lock);
>
> Thanks in advance.
> PAP
>
>
>
>
>
>
>
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Re: what is the function of do_softirq() ?
On Wed, 2013-01-16 at 10:25 +, Anuz Pratap Singh Tomar wrote: > > > On Tue, Jan 15, 2013 at 6:31 AM, horseriver > wrote: > hi: > >what is the function of do_softirq()? Softirq is basically same as bottom half except it is run in irq context.So the question which comes to mind is why softirq?Softirqs can run concurrently on several CPUs and that is why it used in networking. There are other advantages also but it is mostly use case dependent. > >It is called by ksoftirqd() ,which is setup by : > kernel_thread(ksoftirqd, hcpu, CLONE_KERNEL) ; ksoftirq is a saviour thread which takes up the execution of softirq if it finds out that softirq are executing one by one and thereby userspace is not being scheduled or none of other task is getting executed.As threads have low priority it lets other tasks run. > > Please read "Understanding the Linux Kernel" Chapter on Interrupts and > Section on Softirqs and tasklets. Page number 171(might be different > in other editions) onwards. > > > > thanks! > > ___ > Kernelnewbies mailing list > Kernelnewbies@kernelnewbies.org > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > > > > -- > Thank you > Warm Regards > Anuz > ___ > Kernelnewbies mailing list > Kernelnewbies@kernelnewbies.org > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Block device driver: how to terminate the block device if media disappears?
On Sat, 2013-01-12 at 14:39 -0300, Ezequiel Garcia wrote: > On Mon, Jan 7, 2013 at 7:49 AM, John Beard wrote: > > On 21/12/12 18:23, Ezequiel Garcia wrote: > > > >> On Thu, Dec 13, 2012 at 12:31 PM, John Beard > >> wrote: > >>> > >>> What is the right way to terminate requests and delete the gendisk in > >>> the case of physically vanished PCI devices (or even devices in general)? > >>> > >> > >> There are several block driver examples in drivers/block. > >> Or you might want to take a loot at mtdblock.c, or perhaps > >> this simple ubiblock implementation: > >> > >> http://lwn.net/Articles/525957/ > > > > Thanks, Ezequiel - sorry for the delay, I haven't had a chance to touch > > my development computer over the break. The workqueue-based approach > > from ubiblock.c seems to have solved the problem and the device can now > > shut down happily once the request queue is emptied in the submit_req > > call following device removal. > > > > Great! It's nice to hear the hint helped you. > > FYI, a workqueue should always be preferred over a separate kernel thread, > unless there is a good reason for the kernel thread. I was led to believe that the workqueue implementation is based on kernel thread. I wonder in which cases kernel thread should be preferred over workqueue? > ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Regarding module init function
On Tue, 2013-01-08 at 14:51 +0100, Tobias Boege wrote:
> On Tue, 08 Jan 2013, Rahul Bedarkar wrote:
> > Ok. in init/main.c we call do_basic_setup(). Where do_initcalls call each
> > of init functions from __early_initcall_end to __initcall_end. But I don't
> > know from where these values gets initialized.
> >
>
> Take a look at include/linux/init.h. There you can find the macros for
> declaring various init functions. They all go into special sections. The
> rest is linker magic (e.g. arch/x86/kernel/vmlinux.lds{,.S}).
>
> > I want to know when one of auxdriver (selected in from menuconfig) is built
> > as built-in module. When and Who calls it's init function ?
>
> It's, too, in the init.h. There are two definitions of module_init()
> depending on whether MODULE is declared or not. The first definition is
How does the individual driver define this MODULE?I think some macro
magic works here.
> accompanied by a useful comment about where the init function is called in
> either case.
>
> Regards,
> Tobi
>
>
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Re: How kernel handle interrupts[AX88796B network controller]
On Sat, 2012-12-22 at 23:11 +0800, Woody Wu wrote: > On Fri, Dec 21, 2012 at 01:33:03PM -0800, anish kumar wrote: > > On Fri, 2012-12-21 at 23:34 +0800, Woody Wu wrote: > > > On Thu, Dec 20, 2012 at 10:05:05AM -0800, anish singh wrote: > > > > On Dec 20, 2012 6:30 AM, "Woody Wu" wrote: > > > > > > > > > > Hi, List > > > > > > > > > > Where is the Kernel code that handles external interrupts? I want to > > > > > have a look at it but haven't found out where it is. > > > > > > > > > > Actually, I have some basic questions about interrupt handling in > > > > > Linux. > > > > > 1. After Kernel's ISR received an interrupt, I believe it will invoke > > > > > a > > > > >handler defined in a device driver if any. But it should be the > > > > >device driver's responsibility or kernel ISR's responsibility to > > > > >clear (or acknowledge) the interrupt? > > > > If the interrupt in question is currently being handled then in > > > > the case of edge triggered interrupt we just mask the interrupt,set it > > > > pending and bail out.Once the interrupt handler completes then we check > > > > for > > > > pending interrupt and handle it.In level triggered we don't do that. > > > > Kerenel ISR -this is mixture of core kernel interrupt handling code + > > > > your > > > > device driver interrupt handler(if this is chip driver which is > > > > supposed to > > > > get one interrupt and is reponsible for calling other interrupt handlers > > > > based on the chip register status then you do explicit masking unmasking > > > > yourself). > > > > If you device driver is a interrupt controller driver then you register > > > > your driver with kernel interrupt handling code and need to write some > > > > callbacks such as .mask,.unmask and so on.This callbacks are called at > > > > appropiate places whenever the interrupt is raised.This interrupt is > > > > then > > > > passed to drivers who has requested for this interrupt by calling > > > > request_irq. > > > > > > > > > > 2. My device, an AX88796B network controller, asserting the interrupt > > > > >line in a level-triggered manner. Now I met problem with the device > > > > that > > > > >might caused by the CPU interrupt mode is not set as > > > > > level-triggered by > > > > >edge trigger. My CPU is Samsung S3C2410, an ARM920T powered one. > > > > > Does > > > > >anyone know usually where and how should I do this kind of setting? > > > > Just pass the parameter "level triggered" in request_irq in your device > > > > driver. > > > > > > Hi Sign, > > > > > > I searched the interrupt.h for the all the defined flags that I can pass > > > to the request_irq, but there is no a flag looks like "level triggered". > > > Would you tell me what you mean the parameter "level triggered"? > > irq_set_irq_type(info->irq, IRQ_TYPE_LEVEL_LOW) > > > > include/linux/irq.h > > IRQ_TYPE_LEVEL_HIGH - high level triggered > > IRQ_TYPE_LEVEL_LOW - low level triggered > > Thanks. Now I find the function. > > I searched some code about irq in ARM architecure. Some other > people talked about do_IRQ() probabaly is wrong for ARM. There is simply > no that function in ARM. Maybe the do_IRQ in x86 is replaced by > handle_IRQ. arch/arm/kernel/entry-armv.S __irq_svc is called by the arm processor which in turn calls irq_handler macro.I think this is the lowest level handler after which linux interrupt handling takes over. > > For the irq_set_irq_type(), do you think what's the correct place to > call it? Inside my device driver or outside the device driver (probably > in the board definition file)? If that should be called inside a device > driver, should it be the driver probe function or in the open function? > After or before the invocation of request_irq()? irq_set_irq_type() should be called by device driver code not by the board file.It should be called in the probe function AFAIK. > > Sorry for asking too many question. I found the kernel + device driver > irq handling part still not clear to me. You are welcome to ask as many question as you want. > > > > > > > > Thanks. > > > > > > > > > > > > > > > > > > Thanks in advance. > > > > > > > > > > -- > > > > > woody > > > > > I can't go back to yesterday - because I was a different person then. > > > > > > > > > > ___ > > > > > Kernelnewbies mailing list > > > > > Kernelnewbies@kernelnewbies.org > > > > > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > > > > > > ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: How kernel handle interrupts[AX88796B network controller]
On Mon, 2012-12-24 at 22:10 +0800, Woody Wu wrote: > On Fri, Dec 21, 2012 at 01:33:03PM -0800, anish kumar wrote: > > On Fri, 2012-12-21 at 23:34 +0800, Woody Wu wrote: > > > On Thu, Dec 20, 2012 at 10:05:05AM -0800, anish singh wrote: > > > > On Dec 20, 2012 6:30 AM, "Woody Wu" wrote: > > > > > > > > > > Hi, List > > > > > > > > > > Where is the Kernel code that handles external interrupts? I want to > > > > > have a look at it but haven't found out where it is. > > > > > > > > > > Actually, I have some basic questions about interrupt handling in > > > > > Linux. > > > > > 1. After Kernel's ISR received an interrupt, I believe it will invoke > > > > > a > > > > >handler defined in a device driver if any. But it should be the > > > > >device driver's responsibility or kernel ISR's responsibility to > > > > >clear (or acknowledge) the interrupt? > > > > If the interrupt in question is currently being handled then in > > > > the case of edge triggered interrupt we just mask the interrupt,set it > > > > pending and bail out.Once the interrupt handler completes then we check > > > > for > > > > pending interrupt and handle it.In level triggered we don't do that. > > > > Kerenel ISR -this is mixture of core kernel interrupt handling code + > > > > your > > > > device driver interrupt handler(if this is chip driver which is > > > > supposed to > > > > get one interrupt and is reponsible for calling other interrupt handlers > > > > based on the chip register status then you do explicit masking unmasking > > > > yourself). > > > > If you device driver is a interrupt controller driver then you register > > > > your driver with kernel interrupt handling code and need to write some > > > > callbacks such as .mask,.unmask and so on.This callbacks are called at > > > > appropiate places whenever the interrupt is raised.This interrupt is > > > > then > > > > passed to drivers who has requested for this interrupt by calling > > > > request_irq. > > > > > > > > > > 2. My device, an AX88796B network controller, asserting the interrupt > > > > >line in a level-triggered manner. Now I met problem with the device > > > > that > > > > >might caused by the CPU interrupt mode is not set as > > > > > level-triggered by > > > > >edge trigger. My CPU is Samsung S3C2410, an ARM920T powered one. > > > > > Does > > > > >anyone know usually where and how should I do this kind of setting? > > > > Just pass the parameter "level triggered" in request_irq in your device > > > > driver. > > > > > > Hi Sign, > > > > > > I searched the interrupt.h for the all the defined flags that I can pass > > > to the request_irq, but there is no a flag looks like "level triggered". > > > Would you tell me what you mean the parameter "level triggered"? > > irq_set_irq_type(info->irq, IRQ_TYPE_LEVEL_LOW) > > > > include/linux/irq.h > > IRQ_TYPE_LEVEL_HIGH - high level triggered > > IRQ_TYPE_LEVEL_LOW - low level triggered > > Thanks. You saved my ass. > > Be curious, I found the api changes from 2.6 to 3.7. In 2.6, there are > pair of funtions, set_irq_type and set_irq_handle (there is no > irq_set_irq_type in 2.6). Problem is, I cannot find something like > irq_set_irq_handle in 3.7. Does that mean, in 3.7, when > irq_set_irq_type is changed, the associated flow handler is also > changed? In my case, the interrupt was originally assgined with a edge > flow handler and set type as edge irq. After I, by invoking > irq_set_irq_type, change it to level irq, I think the flow handler > should also be changed to a level handle. Is that happened > automatically behind? I search through the code, but did not find where > is it. Why not try calling irq_set_irq_type and check what happens? > > > > > > > > Thanks. > > > > > > > > > > > > > > > > > > Thanks in advance. > > > > > > > > > > -- > > > > > woody > > > > > I can't go back to yesterday - because I was a different person then. > > > > > > > > > > ___ > > > > > Kernelnewbies mailing list > > > > > Kernelnewbies@kernelnewbies.org > > > > > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > > > > > > ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: What does ISA/PCI really mean to ARM architecture?
On Thu, 2012-12-27 at 11:22 -0500, jonsm...@gmail.com wrote: > On Thu, Dec 27, 2012 at 3:27 AM, Woody Wu wrote: > > Hi, list > > > > I know this might be a very basic question. But I really don't clear at > > it. > > > > Can a peripheral chip that claims to be ISA or PCI device be used in a > > ARM based embedded system? For these kind of chips, I only concern > > about the planar kind of devices, means they are not on a dedicated > > expansion card. > > > > From hardware point of view, to attach a ISA or PCI planar chip, is > > there any requirement need to fulfill on a ARM board? > > See if your ARM CPU has an interface for SRAM (in addition to DRAM). > You can use a SRAM chip select to access ISA type devices. But you may Would you mind explaining this in detail? > need additional buffers/latches to do this. > > Another solution is to attach you peripherals using USB. Almost all Connect using USB what does this mean? > embedded wifi chips are attached this way. The USB connectors aren't > required, you can route USB around on your PCB. USB hub chips are > $0.35 if you need more ports. USB Ethernet chips are available. > > Other options include SPI/I2C. It is worthwhile to investigate these Only chips which support SPI/I2C can be used but ISA/PCI is completely orthogonal to this AFAIK. > serial solutions before doing a parallel solution. Parallel buses eat > up a lot of PCB space. > > > > > > From Linux driver point of view, what are needed to support an ISA or > > PCI driver in ARM architecture? More important, is ISA or PCI device a > > platform device? If not, how to add these kind of devices in my board > > definition? > > > > I know my question might not be reasonable enough, if I messed concepts, > > please sort me out. > > > > > > Thanks in advance. > > > > > > -- > > woody > > I can't go back to yesterday - because I was a different person then. > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > > the body of a message to majord...@vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > Please read the FAQ at http://www.tux.org/lkml/ > > > > -- > Jon Smirl > jonsm...@gmail.com > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: What does ISA/PCI really mean to ARM architecture?
On Thu, 2012-12-27 at 10:51 +0100, Geert Uytterhoeven wrote:
> On Thu, Dec 27, 2012 at 9:27 AM, Woody Wu wrote:
> > Can a peripheral chip that claims to be ISA or PCI device be used in a
> > ARM based embedded system? For these kind of chips, I only concern
> > about the planar kind of devices, means they are not on a dedicated
> > expansion card.
> >
> > From hardware point of view, to attach a ISA or PCI planar chip, is
> > there any requirement need to fulfill on a ARM bard?
arm AFAIK is only used in embedded system but ISA/PCI buses are
generally part of 'big systems' and most of the times it refers to x86
PC.
> >
> > From Linux driver point of view, what are needed to support an ISA or
> > PCI driver in ARM architecture? More important, is ISA or PCI device a
> > platform device? If not, how to add these kind of devices in my board
> > definition?
AFAIK, Platform device is just a way to add a particular driver whose
probe can't be called at runtime.Mostly platform device is part of
system on chip.
PCI devices probe function will be called by the PCI bus as and when it
detects any activity on the bus.So you don't need PCI device to be a
platform device.
>
> An ISA device is typically a platform device. For ARM, which uses device
> trees,
Don't know much about ISA device to comment on this but people familiar
with this can enlighten us as to the reason why it is platform device in
detail.
> this means you define it in the device tree.
>
> A PCI device is not a platform device, as devices on a PCI bus can be
> probed automatically. The PCI host bridge is typically a platform device,
> though, so it it should be in your device tree.
>
> Gr{oetje,eeting}s,
>
> Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 --
> ge...@linux-m68k.org
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like
> that.
> -- Linus Torvalds
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majord...@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
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Re: How kernel handle interrupts[AX88796B network controller]
On Fri, 2012-12-21 at 23:34 +0800, Woody Wu wrote: > On Thu, Dec 20, 2012 at 10:05:05AM -0800, anish singh wrote: > > On Dec 20, 2012 6:30 AM, "Woody Wu" wrote: > > > > > > Hi, List > > > > > > Where is the Kernel code that handles external interrupts? I want to > > > have a look at it but haven't found out where it is. > > > > > > Actually, I have some basic questions about interrupt handling in Linux. > > > 1. After Kernel's ISR received an interrupt, I believe it will invoke a > > >handler defined in a device driver if any. But it should be the > > >device driver's responsibility or kernel ISR's responsibility to > > >clear (or acknowledge) the interrupt? > > If the interrupt in question is currently being handled then in > > the case of edge triggered interrupt we just mask the interrupt,set it > > pending and bail out.Once the interrupt handler completes then we check for > > pending interrupt and handle it.In level triggered we don't do that. > > Kerenel ISR -this is mixture of core kernel interrupt handling code + your > > device driver interrupt handler(if this is chip driver which is supposed to > > get one interrupt and is reponsible for calling other interrupt handlers > > based on the chip register status then you do explicit masking unmasking > > yourself). > > If you device driver is a interrupt controller driver then you register > > your driver with kernel interrupt handling code and need to write some > > callbacks such as .mask,.unmask and so on.This callbacks are called at > > appropiate places whenever the interrupt is raised.This interrupt is then > > passed to drivers who has requested for this interrupt by calling > > request_irq. > > > > > > 2. My device, an AX88796B network controller, asserting the interrupt > > >line in a level-triggered manner. Now I met problem with the device > > that > > >might caused by the CPU interrupt mode is not set as level-triggered by > > >edge trigger. My CPU is Samsung S3C2410, an ARM920T powered one. Does > > >anyone know usually where and how should I do this kind of setting? > > Just pass the parameter "level triggered" in request_irq in your device > > driver. > > Hi Sign, > > I searched the interrupt.h for the all the defined flags that I can pass > to the request_irq, but there is no a flag looks like "level triggered". > Would you tell me what you mean the parameter "level triggered"? irq_set_irq_type(info->irq, IRQ_TYPE_LEVEL_LOW) include/linux/irq.h IRQ_TYPE_LEVEL_HIGH - high level triggered IRQ_TYPE_LEVEL_LOW - low level triggered > > Thanks. > > > > > > > > > > Thanks in advance. > > > > > > -- > > > woody > > > I can't go back to yesterday - because I was a different person then. > > > > > > ___ > > > Kernelnewbies mailing list > > > Kernelnewbies@kernelnewbies.org > > > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: How kernel handle interrupts
On Fri, 2012-12-21 at 17:34 +0800, Woody Wu wrote: > > 在 2012-12-21 AM2:05，"anish singh" 写 > 道： > > > > > > On Dec 20, 2012 6:30 AM, "Woody Wu" wrote: > > > > > > Hi, List > > > > > > Where is the Kernel code that handles external interrupts? I want > to > > > have a look at it but haven't found out where it is. > > > > > > Actually, I have some basic questions about interrupt handling in > Linux. > > > 1. After Kernel's ISR received an interrupt, I believe it will > invoke a > > >handler defined in a device driver if any. But it should be the > > >device driver's responsibility or kernel ISR's responsibility > to > > >clear (or acknowledge) the interrupt? > > If the interrupt in question is currently being handled then in > > the case of edge triggered interrupt we just mask the interrupt,set > it pending and bail out.Once the interrupt handler completes then we > check for pending interrupt and handle it.In level triggered we don't > do that. > > Kerenel ISR -this is mixture of core kernel interrupt handling code > + your device driver interrupt handler(if this is chip driver which is > supposed to get one interrupt and is reponsible for calling other > interrupt handlers based on the chip register status then you do > explicit masking unmasking yourself). > > If you device driver is a interrupt controller driver then you > register your driver with kernel interrupt handling code and need to > write some callbacks such as .mask,.unmask and so on.This callbacks > are called at appropiate places whenever the interrupt is raised.This > interrupt is then passed to drivers who has requested for this > interrupt by calling request_irq. > > Sorry not fully understand . My device is an interrupt line is back to > inactive.Ethernet controller. It needs to response TX and RX > interrupts triggered by the device itself. In this case , my driver is > a chip driver or interrupt controller driver in your terms? Your device is neither of these. > > If my driver needs to do the mask and unmask job, what's the kernel > API I should call? You don't need to worry about mask and unmask job AFAIK. > > And , I don't understand why there exists differences between level > and edge triggered interrupts in terms of kernel handling. Level type interrupts are active as long as the hardware line has the active level. This may require to mask the interrupt and unmask it after the associated handler has acknowledged the device, so the interrupt line is back to inactive. Edge interrupt occurs on the falling and/or rising edge of a hardware signal.The occurrence is latched into the irq controller hardware and must be acked in order to be re-enabled. Read the code /kerel/irq/chip.c(handle_edge_irq & handle_level_irq) > > I know my questions might be basic , so would please tell me what's If it was not basic then this question wouldn't be in kernelnewbies right :)? > the kernel code for ARM architecture doing these complex jobs as you > explained? You don't need to worry about it but if you want to know further then I suggest tracing the call flow from asm interrupt handler(I believe do_irq but not sure) in arm to handle_edge_irq call flow by adding some logs or just browsing the code. > > Thanks in advance ! > > > > > > > > > 2. My device, an AX88796B network controller, asserting the > interrupt > > >line in a level-triggered manner. Now I met problem with the > device that > > >might caused by the CPU interrupt mode is not set as > level-triggered by > > >edge trigger. My CPU is Samsung S3C2410, an ARM920T powered > one. Does > > >anyone know usually where and how should I do this kind of > setting? > > Just pass the parameter "level triggered" in request_irq in your > device driver. > > > > > > > > > > > Thanks in advance. > > > > > > -- > > > woody > > > I can't go back to yesterday - because I was a different person > then. > > > > > > ___ > > > Kernelnewbies mailing list > > > Kernelnewbies@kernelnewbies.org > > > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > > ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Callback function from kernel module
On Sat, 2012-11-03 at 21:56 +0530, jeshkumar...@gmail.com wrote: > hello Mulyadi, > > As per my design, a userspace application shall call some function in > the application for each interrupt occur in particular kernel > module. So what mechanism shall go ? As subramaniam referred kobject, > I am going on with it. ( understanding kobject) Why userspace is bothered about interrupts in the kernel.Something is inherently wrong in your understanding. A detailed problem description would help you. > > Sent from my HTC > Excuse for typo. > > - Reply message - > From: "Mulyadi Santosa" > Date: Sat, Nov 3, 2012 9:42 pm > Subject: Callback function from kernel module > To: "Jeshwanth Kumar N K Jeshu" > Cc: "kernelnewbies" > > > Hi.. > > On Sat, Nov 3, 2012 at 8:44 PM, Jeshwanth Kumar N K Jeshu > wrote: > > Hello All, > > > > Can I call userspace function from kernel module ? Actually I need > to > > process some data in user space for every event occured in kernel > module. > > user space function or user space program? for later, IIRC you can use > usermode_helper... > > > -- > regards, > > Mulyadi Santosa > Freelance Linux trainer and consultant > > blog: the-hydra.blogspot.com > training: mulyaditraining.blogspot.com > > > ___ > Kernelnewbies mailing list > Kernelnewbies@kernelnewbies.org > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Finding the interrupt vector of a given IRQ
On Fri, 2012-10-19 at 10:34 +0530, Arun KS wrote:
> Hi Anish,
>
> On Mon, May 28, 2012 at 9:16 AM, anish singh
> wrote:
> On Mon, May 28, 2012 at 2:57 AM, richard -rw- weinberger
> wrote:
> > On Sun, May 27, 2012 at 2:02 AM, Mark Farnell
> wrote:
> >> In the kernel, how can I find out the interrupt vector
> number of a
> >> given IRQ (for example, IRQ7)?
> >>
> >> Within the kernel module, I would like to manually set the
> IRQ using
> >> the assembly code:
> >>
> >> asm("int $");
> >>
> >> and let the IRQ handler installed by a different module
> catch that interrupt.
> >>
> >> Is this possible?
> >
> > No really because not all IRQ have an interrupt line to the
> CPU.
> > Linux can multiplex and emulate them. Think of GPIO drivers
> with
> > interrupt support.
>
> Can you please describe this in detail?It would really help a
> lot of
> people like me.Does multiplex mean that all numbers starting
> from
> 0,1,2,3,.. TOTAL-interrupt will have interrupt lines
> associated with it
> eventhough all interrupt numbers are not linear?
>
> GPIOs are grouped as banks. Let’s say 32 gpios are in a bank.
> There will be only single interrupt line to interrupt controller for a
> bank.
>
>
> Consider that you have configured gpio1 and gpio16 as interrupts.
> Even if interrupt happens on gpio 1 or gpio 16, the same interrupt
> line will be triggered to
>
> Interrupt controller.
>
>
> Now the gpio driver has to figure out reading the Interrupt status
>
> Register of GPIO to find which interrupt (gpio1 or gpio16) has really
> fired.
And this is done by this way:
Suppose we have a chip(mfd-multi-funcion-driver) driver which is
connected to processor using a gpio - this gpio line acts as interrupt
line from the processor
++
+ Processor+ + Chip +>USB interrupt handler
+ +gpio->+ MFD+>dock interrupt handler
++>UART interrupt handler
++>Factory cable interrupt handler
So the code will be as follows:
handler_function()
{
/* find out which interrupt is triggered */
/* it can be usb,dock,uart or factory cable */
ret_irq = read_mfd_register();
/*
* ok we found out the interrupt line, get a corresponding
* software linux irq number by calling
* irq_domain_add_linear
* irq_create_mapping
* you would have made this calls in the probe probably
*/
handle_nested_irq(ret_irq);
}
handle_nested_irq inturn will call all the irq_handlers in the system
for your UART,usb and dock driver.
mfd_driver()
{
request_irq(gpio_to_irq(gpio), handler_function);
}
Hope I have not missed anything.
>
> So in this case a single interrupt line is multiplex for 32 gpio
> interrupts.
>
>
> HTH.
>
> Thanks,
> Arun
>
> > Anyway, why to you think you need to trigger the raw IRQ
> manually?
> > This sounds really odd...
> >
> >
> > --
> > Thanks,
> > //richard
> >
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Re: Mult core cpus - SMP
On Thu, 2012-09-13 at 15:33 +0400, Denis Kirjanov wrote: Hello Denis, Don't top post!! > Yes, for example IBM 970MP CPU: > > • Dual processors on a single chip > – Each processor has its own dedicated storage subsystem, including a > 1 MB L2 cache per core. > – Each processor has its own dedicated resets, external interrupt, > thermal diode, and voltage plane > (common logic is powered on). > – Common logic provides arbitration for bus access between the two cores. > – A single external interface allows a companion chip with a single > interface to support two processors. > > On 9/13/12, Kshemendra KP wrote: > > Hi, > > > > Does multi core CPU act like SMP system. Preemption will effectively turn a UniProcessor system into an effective SMP system. > > > > Regards > > > > Kshemendra > > > > ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Writing I2C chip driver in combination with other structure
On Fri, 2012-07-20 at 16:24 +0530, aurum spark wrote: > Hi All, > > I have written and seen lot of code of i2c drivers for input subsystem > devices and much familiar with that. Now I have started writing driver > for one chip that is not exactly type of input device. So, little bit > confused about how should be the driver architecture so that it will > be a clean code yet simple. Following text and diagram explains short > functional description of chip. > > > Chip Interface :- > == > > > == === > | || I2C | > | | - I2C --- | Device| > |ARM | - Bus -- | With rw| Input Connect > | || regs | > | | ---| | > == INTR === > > So above picture depicts how chip is interfaced to ARM CPU. This chip > has some registers which are rw and can be used to read certain > information from chip or to program it. This chip is capable of giving > intterupt to CPU. This chip has one input which it like some cable > connection. It detects when this cable is connected and raises the > interrupt. > > Functionality Expected in Driver:- > === > > 1. Driver should communicate with chip over I2C. > 2. Driver should report event to user space upon receiving interrupt > from I2C device. > 3. Driver should be capable of programming I2C chip @ the time of > initialization as well should be capable of changing registers as and > when Linux User Space application wants to. > > What I have thought of:- > == > > #1 definitely makes this as i2c client driver(chip driver) > > #2 Here I have few options > > a) Shall I use input subsystem mechanism to report interrupt as an > event to user space ? In this case it's combination of I2C + input > subsystem. Then application can read something over i2c and decide > next flow, > > OR > > b) Shall I use some sysfs based interface on which application can do > select sys call and can receive event ? for this nothing extra > required. > > #3 Since approach in #2 is not fixed here also there are multiple options > a) This can be written as I2C client + char driver so that it can > have ioctls to send commands to i2c chip based on applications demand. What does this chip do and why does it need to do I2C transaction based on application demand? > b) We can provide sysfs interface to user space to send commands to > i2c device as and when required at runtime. > > > As per my thoughts I am not sure shall I make this as input device > just to report one event upon getting interrupt from device. Also will > it be ok to have this as char driver in combination with i2c chip > driver ? > Please guide me and take me to correct source or documentation or to > source code of some driver for this kind of device. Does i2c support > ops like fbops ? > > > Regards, > ~/Aurum > > ___ > Kernelnewbies mailing list > Kernelnewbies@kernelnewbies.org > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: How to allocate hugepage in kernel module?
On Fri, 2012-08-10 at 09:00 +0900, J.Hwan Kim wrote: > I set the __GFP_COMP flag to __get_free_pages(), > but the result was same. Does this help? sourd/core/memalloc.c +170 > 2012년 08월 09일 17:59, Denis Kirjanov 쓴 글: > > Forgot to CC kernelnewbies: > > > > Did you pass the __GFP_COMP flag to __get_free_pages? > > > > > > On 8/9/12, J.Hwan Kim wrote: > >> Hi, everyone > >> > >> How can I allocate physically contiguous huge page in kernel module ? > >> The routine of _get_fee_pages() fails whenever there are much free > >> memory in system. > >> > >> I found the procedures for set hugepages with sysctl or > >> /proc/sys/vm/nr_hugepages > >> but I've not found the api for allocate the huge page in kernel. > >> > >> Thanks in advnace. > >> > >> Best Regards, > >> J.Hwan Kim > >> > >> > >> > >> ___ > >> Kernelnewbies mailing list > >> Kernelnewbies@kernelnewbies.org > >> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > >> > > > > > ___ > Kernelnewbies mailing list > Kernelnewbies@kernelnewbies.org > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Why can not processes switch in atomic context?
On Tue, 2012-07-03 at 22:24 +0800, Parmenides wrote: > Hi, > > It is said that kernel can not be preempted in interrupt context > and when it is in a critical section protected by a spin lock > > 1. For the spinlock case, it is easy to get if preemption is allowed > in critical section, the purpose of protection provided by spinlock > can not be achieved readily. I don't know what you mean here.Please clarify. > > 2. For the interrupt context case, I think when processing interrupt, > kernel can be preempted in principle. But, this really increases the > interrupt processing time which further cause longer response time and > data missing in device. Except that, is there any other reasons? data missing in device.Can you elaborate that? Stack space is pretty limited in ISR context.Does that give you a clue? > > 3. Kernel is responsible for prohibiiting passive process switches, > namely preemption, in the above cases. But, It seems that it does not > take care of active process swtiches, namely yield. For example, some > code in a critical section protected by a spinlock can invoke > schedule() to switch process passively. Is this the case? I don't understand this question but we don't switch when we are holding spinlock as that will jeopardize the integrity of the system i.e. suppose you slept while holding spinlock.What would happen? > > ___ > Kernelnewbies mailing list > Kernelnewbies@kernelnewbies.org > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Missing Key-codes from input.h file.
On Wed, 2012-06-27 at 11:20 +0530, Dharam Kumar wrote: > On Tue, Jun 26, 2012 at 1:13 PM, Matthias Brugger > wrote: > > On 06/26/2012 08:47 AM, Dharam Kumar wrote: > >> > >> On Tue, Jun 26, 2012 at 12:02 PM, anish kumar > >> wrote: > >>> > >>> On Mon, 2012-06-25 at 23:24 +0530, Dharam Kumar wrote: > >>>> > >>>> On Mon, Jun 25, 2012 at 10:47 PM, anish kumar > >>>> wrote: > >>>>> > >>>>> On Mon, 2012-06-25 at 18:52 +0530, Dharam Kumar wrote: > >>>>>> > >>>>>> Hi, > >>>>>> I'm working on a module which is an input device and hence it needs to > >>>>>> report certain key events. > >>>>>> > >>>>>> While browsing through the , I did find most of the > >>>>>> key-codes(which I need to use)already defined but not all. > >>>>>> > >>>>>> > >>>>>> Few of the KEY_xxx which i could not find are: > >>>>>> > >>>>>> > >>>>>> a.) A Key for going to the previous channel. > >>>>>> b.) Keys for Moving upper-right, lower-right, upper-left and > >>>>>> lower-left direction(probably a GUI(grid of icons),where you move > >>>>>> diagonally) > >>>>>> d.) A key for Subpicture (this 'subpicture' key is deeined in > >>>>>> CEA-931C). > >>>>> > >>>>> I think you are interested in the user space implementation of > >>>>> the keys reported by the input subsystem of kernel. > >>>>> Keys reported by the driver->input subsystem->reported to user space. > >>>>> > >>>>> I am not sure about linux way of reporting keys but in android the key > >>>>> is reported at a particular sysfs file and this sysfs file is read by > >>>>> eventhub.cpp.This file in turn is responsible for sending the events > >>>>> to particular application and it is the responsibility of the > >>>>> application how they interpret this keys.It can interpret events by > >>>>> moving diagonally a pointer/touch or going left/right. > >>>>> > >>>> Thanks Anish ! To be clear, i just want to know the key-code > >>>> which will be used by the Input Subsytem of the Kernel. > >>>> > >>>> For example, in file you will find a lot of #defines > >>>> like the below,mapping different kind of key events to some key-code > >>>> or value : > >>>> #define KEY_UP 0xXYZ > >>>> #define KEY_DOWN 0xABC and so on... > >>>> > >>>> Now, I'm looking for key events like: > >>>> #define KEY_PREVIOUSCHANNEL > >>>> #define KEY_RIGHTUP > >>>> #define kEY_RIGHTLEFT > >>>> #define kEY_SUBPICTURE and so on... > >>>> > >>>> You are probably right , that Userspace reads the key-events/key-codes > >>>> from certain sysfs entries exported by Android Linux Kernel and these > >>>> key-codes/events will be handled accordingly by the respective > >>>> Framework/Application. But I'm really not interested in how and what > >>>> Userspace gets from Kernel. > >>>> I'm interested in what values the Kernel or input subsystem will > >>>> provide to such keys.. > >>> > >>> Do you have such keys in your device KEY_RIGHTUP? > >>> > >> Yes, my device is supposed to support such keys: > >> RIGHTUP --> moves cursor upper-right direction. > >> RIGHTDOWN ---> moves cursor lower-right direction. > >> and similar keys for upper-left and lower-left cursor direction. > >> Sadly, I could not find any #define in input.h file for such key events. > > > > > > From your response I interpret that you have some kind of custom key-pad, or > > anything similar which is not a standard keyboard. > > > You are right that it is not a standard keyboard. In fact, these are > Remote Controller(or Remote Control) keys as defined in MHL > Specifications(www.mhltech.org). > Now, MHL Specs is closely related to HDMI specifications.Hence, my > assumption is that such keys might be the part of HDMI-CEC > specifications and would have been pic
Re: Missing Key-codes from input.h file.
On Tue, 2012-06-26 at 09:43 +0200, Matthias Brugger wrote: > On 06/26/2012 08:47 AM, Dharam Kumar wrote: > > On Tue, Jun 26, 2012 at 12:02 PM, anish kumar > > wrote: > >> On Mon, 2012-06-25 at 23:24 +0530, Dharam Kumar wrote: > >>> On Mon, Jun 25, 2012 at 10:47 PM, anish kumar > >>> wrote: > >>>> On Mon, 2012-06-25 at 18:52 +0530, Dharam Kumar wrote: > >>>>> Hi, > >>>>> I'm working on a module which is an input device and hence it needs to > >>>>> report certain key events. > >>>>> > >>>>> While browsing through the , I did find most of the > >>>>> key-codes(which I need to use)already defined but not all. > >>>>> > >>>>> > >>>>> Few of the KEY_xxx which i could not find are: > >>>>> > >>>>> > >>>>> a.) A Key for going to the previous channel. > >>>>> b.) Keys for Moving upper-right, lower-right, upper-left and > >>>>> lower-left direction(probably a GUI(grid of icons),where you move > >>>>> diagonally) > >>>>> d.) A key for Subpicture (this 'subpicture' key is deeined in > >>>>> CEA-931C). > >>>> I think you are interested in the user space implementation of > >>>> the keys reported by the input subsystem of kernel. > >>>> Keys reported by the driver->input subsystem->reported to user space. > >>>> > >>>> I am not sure about linux way of reporting keys but in android the key > >>>> is reported at a particular sysfs file and this sysfs file is read by > >>>> eventhub.cpp.This file in turn is responsible for sending the events > >>>> to particular application and it is the responsibility of the > >>>> application how they interpret this keys.It can interpret events by > >>>> moving diagonally a pointer/touch or going left/right. > >>>> > >>> Thanks Anish ! To be clear, i just want to know the key-code > >>> which will be used by the Input Subsytem of the Kernel. > >>> > >>> For example, in file you will find a lot of #defines > >>> like the below,mapping different kind of key events to some key-code > >>> or value : > >>> #define KEY_UP 0xXYZ > >>> #define KEY_DOWN 0xABC and so on... > >>> > >>> Now, I'm looking for key events like: > >>> #define KEY_PREVIOUSCHANNEL > >>> #define KEY_RIGHTUP > >>> #define kEY_RIGHTLEFT > >>> #define kEY_SUBPICTURE and so on... > >>> > >>> You are probably right , that Userspace reads the key-events/key-codes > >>> from certain sysfs entries exported by Android Linux Kernel and these > >>> key-codes/events will be handled accordingly by the respective > >>> Framework/Application. But I'm really not interested in how and what > >>> Userspace gets from Kernel. > >>> I'm interested in what values the Kernel or input subsystem will > >>> provide to such keys.. > >> Do you have such keys in your device KEY_RIGHTUP? > >> > > Yes, my device is supposed to support such keys: > > RIGHTUP --> moves cursor upper-right direction. > > RIGHTDOWN ---> moves cursor lower-right direction. > > and similar keys for upper-left and lower-left cursor direction. > > Sadly, I could not find any #define in input.h file for such key events. > > From your response I interpret that you have some kind of custom > key-pad, or anything similar which is not a standard keyboard. > > If there are no such defines in the Kernel, it's probably because no one > has had the need for them up to now. > > I think the implementation should be done as Anish described beforehand. > Anyway you can add some defines to your Kernel if this is a requirement and probably submit your first patch to the kernel but I am not clear about the policy regarding adding new keys in the kernel.However sending the patch would be better than speculating. > for you. > > Regards, > Matthias > > >>>> Not sure if this is what you are interested in but would have been > >>>> better if you had described the problem in more detail. > >>>>> > >>>>> > >>>>> Does anybody have any idea about this? > >>>>> > >>>>> > >>>>> - > >>>>> Dharam > >>>>> ___ > >>>>> Kernelnewbies mailing list > >>>>> Kernelnewbies@kernelnewbies.org > >>>>> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > >>>> > >>>> > >> > >> > > > > ___ > > Kernelnewbies mailing list > > Kernelnewbies@kernelnewbies.org > > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > > > > ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Missing Key-codes from input.h file.
On Mon, 2012-06-25 at 23:24 +0530, Dharam Kumar wrote: > On Mon, Jun 25, 2012 at 10:47 PM, anish kumar > wrote: > > On Mon, 2012-06-25 at 18:52 +0530, Dharam Kumar wrote: > >> Hi, > >> I'm working on a module which is an input device and hence it needs to > >> report certain key events. > >> > >> While browsing through the , I did find most of the > >> key-codes(which I need to use)already defined but not all. > >> > >> > >> Few of the KEY_xxx which i could not find are: > >> > >> > >> a.) A Key for going to the previous channel. > >> b.) Keys for Moving upper-right, lower-right, upper-left and > >> lower-left direction(probably a GUI(grid of icons),where you move > >> diagonally) > >> d.) A key for Subpicture (this 'subpicture' key is deeined in > >> CEA-931C). > > I think you are interested in the user space implementation of > > the keys reported by the input subsystem of kernel. > > Keys reported by the driver->input subsystem->reported to user space. > > > > I am not sure about linux way of reporting keys but in android the key > > is reported at a particular sysfs file and this sysfs file is read by > > eventhub.cpp.This file in turn is responsible for sending the events > > to particular application and it is the responsibility of the > > application how they interpret this keys.It can interpret events by > > moving diagonally a pointer/touch or going left/right. > > > Thanks Anish ! To be clear, i just want to know the key-code > which will be used by the Input Subsytem of the Kernel. > > For example, in file you will find a lot of #defines > like the below,mapping different kind of key events to some key-code > or value : > #define KEY_UP 0xXYZ > #define KEY_DOWN 0xABC and so on... > > Now, I'm looking for key events like: > #define KEY_PREVIOUSCHANNEL > #define KEY_RIGHTUP > #define kEY_RIGHTLEFT > #define kEY_SUBPICTURE and so on... > > You are probably right , that Userspace reads the key-events/key-codes > from certain sysfs entries exported by Android Linux Kernel and these > key-codes/events will be handled accordingly by the respective > Framework/Application. But I'm really not interested in how and what > Userspace gets from Kernel. > I'm interested in what values the Kernel or input subsystem will > provide to such keys.. Do you have such keys in your device KEY_RIGHTUP? > > Not sure if this is what you are interested in but would have been > > better if you had described the problem in more detail. > >> > >> > >> Does anybody have any idea about this? > >> > >> > >> - > >> Dharam > >> ___ > >> Kernelnewbies mailing list > >> Kernelnewbies@kernelnewbies.org > >> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > > > > ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Missing Key-codes from input.h file.
On Mon, 2012-06-25 at 18:52 +0530, Dharam Kumar wrote: > Hi, > I'm working on a module which is an input device and hence it needs to > report certain key events. > > While browsing through the , I did find most of the > key-codes(which I need to use)already defined but not all. > > > Few of the KEY_xxx which i could not find are: > > > a.) A Key for going to the previous channel. > b.) Keys for Moving upper-right, lower-right, upper-left and > lower-left direction(probably a GUI(grid of icons),where you move > diagonally) > d.) A key for Subpicture (this 'subpicture' key is deeined in > CEA-931C). I think you are interested in the user space implementation of the keys reported by the input subsystem of kernel. Keys reported by the driver->input subsystem->reported to user space. I am not sure about linux way of reporting keys but in android the key is reported at a particular sysfs file and this sysfs file is read by eventhub.cpp.This file in turn is responsible for sending the events to particular application and it is the responsibility of the application how they interpret this keys.It can interpret events by moving diagonally a pointer/touch or going left/right. Not sure if this is what you are interested in but would have been better if you had described the problem in more detail. > > > Does anybody have any idea about this? > > > - > Dharam > ___ > Kernelnewbies mailing list > Kernelnewbies@kernelnewbies.org > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Continuous Interrupt Problem
On Fri, 2012-06-15 at 03:22 -0700, Shaji Yusuf wrote:
> Is the issue resolved?
>
>
> This seems to be more of either a device that's buggy or some
> misunderstanding in understanding the device specs.
I checked with siddharth and understanding in device specs
was the problem.
>
>
> I had a similar issue with one of our devices. When I get an interrupt
> I would do some thing in the device (reading buffers writing some
> registers and stuff) that should reset the Interrupt pin to high state
> again. But the hardware had a bug that would not let the Interrupt pin
> reset, and once I return from the Interrupt it would strike again
> causing the system to freeze.
>
>
> Thanks
>
> Shaji Yusuf
>
>
>
>
>
> __
> From: siddharth saxena
> To: anish singh
> Cc: Arun KS ; Sarbojit Ganguly
> ; kernelnewbies@kernelnewbies.org
> Sent: Thursday, June 14, 2012 2:35 PM
> Subject: Re: Continuous Interrupt Problem
>
>
> Initialized in Probe :
>
> if (device->irq) {
> ret = request_irq(device->irq, ts_int_handler,
> IRQF_TRIGGER_LOW, DRIVER_NAME, device);
> if (ret) {
> pr_err("unable to register touch irq.(%s)\r\n",
> device->input_dev->name);
> goto err_request_irq;
> }
> }
>
>
>
> The pin by default has to be initialized to Active Low.
>
>
>
>
> On Thu, Jun 14, 2012 at 2:24 PM, anish singh
> wrote:
> On Thu, Jun 14, 2012 at 2:11 PM, siddharth saxena
> wrote:
> > Hi Arun
> >
> > I tried changing the flag to IRQF_TRIGGER_HIGH but then
> device is behaving
> > abnormally(Hangs and is dead after some time).
> > Flooding interrupts still observed. Problem not solved.
> >
> > I want to know, are we supposed to change interrupt pin
> status or it is done
> > automatically when we return IRQ_HANDLED.
>
> why don't you paste the code for your probe routine where you
> are
> calling request_irq.
> Are you using threaded irq?It would be difficult to diagnose
> the
> problem without looking
> at your TSP manual and your code to find out the problem.
> >
> >
> >
> >
> > On Thu, Jun 14, 2012 at 12:21 PM, Sarbojit Ganguly
> > wrote:
> >>
> >> Hi Arun,
> >>
> >> While I agree to your pointers but he is facing the problem
> of
> >> "interrupt floods" even before he touches.
> >> IMHO the culprit could be the flag.
> >>
> >> On 14 June 2012 12:01, Arun KS wrote:
> >> > Hello Siddharth,
> >> >
> >> > On Thu, Jun 14, 2012 at 10:34 AM, siddharth saxena
> >> > wrote:
> >> >> Hi all
> >> >>
> >> >> I need help with an issue.
> >> >> I have written a touch driver for a device and used the
> flag
> >> >> IRQF_TRIGGER_LOW to request irq.
> >> >> Now, when I boot the device, the touch interrupts are
> coming already
> >> >> without
> >> >> touching the screen.
> >> >> Continuous interrupts are occurring without any touch.
> >> >
> >> > Probably the default state of the gpio pin(which you
> configured as
> >> > irq) is low. Check your HW schematic.
> >> >
> >> > TSC should have interrupt polarity(Active High/Low),
> which you have to
> >> > choose depending on your schematic while initiallizing
> the TSC.
> >> > Also different modes like assert interrupt when finger
> moving, when
> >> > finger touch, or assert periodically.
> >> >
> >> > Hope these pointer will help you.
> >> >
> >> > Thanks,
> >> > Arun
> >> >
> >> >>
> >> >>
> >> >>
> >> >> --
> >> >> Regards
> >> >> Siddharth Saxena
> >> >>
> >> >>
> >> >> ___
> >> >> Kernelnewbies mailing list
> >> >> Kernelnewbies@kernelnewbies.org
> >> >>
> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
> >> >>
> >> >
> >> > ___
> >> > Kernelnewbies mailing list
> >> > Kernelnewbies@kernelnewbies.org
> >> >
> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
> >>
> >>
> >>
> >> --
> >> Regards,
> >> Sarbojit
> >
> >
> >
> >
> > --
> > Regards
> > Siddharth Saxena
> >
> >
> > ___
> > Kernelnewbies mailing list
> > Kernelnewbies@kernelnewbies.org
>
request_firmware question
Hi, Now I have switched to using request_firmware api and after using firmware, memory is being released. Does it save kernel memory compare to case when I am having a having a local static firmware buffer(very big) from which I used to get the firmware and write it to the chip? As I know request_firmware api has several advantages but what I want to know is the advantages related to kernel memory footprint. Thanks for the help. ps:I asked the same question in #kernelnewbies IRC ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Scull -unable to handle kernel paging request
Hello,
Testing the scullwuid produced attached crash logs.
Combination of read and write using "dd" and "cat"
caused this problem.
I don't exactly remember exactly what caused the problem
but combination of read and write did it.
Reproduction would not be possible but just want to know
why this happened as anyone looking into the code would
come to the conclusion that proper locking is in place.
Below is small part of the crash logs:
[21028.412827] BUG: unable to handle kernel paging request at 00300d04
[21028.412832] IP: [] _copy_from_user+0x97/0x130
[21028.412839] *pde = 6fa0b067
[21028.412842] Oops: 0003 [#1] SMP
[21028.412933] Call Trace:
[21028.412940] [] ? scull_write+0x193/0x204 [scull]
[21028.412946] [] ? vfs_write+0xa2/0x190
[21028.412949] [] ? scull_write+0x0/0x204 [scull]
[21028.412953] [] ? sys_write+0x42/0x70
[21028.412958] [] ? syscall_call+0x7/0xb
[21028.412963] [] ? calibrate_delay_direct+0x5a/0xfb
Some of the below code is removed for fitting it into this mail:
ssize_t scull_write(struct file *filp, const char __user *buf, size_t count,
loff_t *f_pos)
{
if (down_interruptible(&dev->sem))
return -ERESTARTSYS;
dptr = scull_follow(dev, item);
if (dptr == NULL)
goto out;
if (!dptr->data) {
dptr->data = kmalloc(qset * sizeof(char *), GFP_KERNEL);
if (!dptr->data)
goto out;
memset(dptr->data, 0, qset * sizeof(char *));
}
if (!dptr->data[s_pos]) {
dptr->data[s_pos] = kmalloc(quantum, GFP_KERNEL);
if (!dptr->data[s_pos])
goto out;
/* write only up to the end of this quantum */
if (count > quantum - q_pos)
count = quantum - q_pos;
if (copy_from_user(dptr->data[s_pos]+q_pos, buf, count)) {
retval = -EFAULT;
goto out;
}
Used: https://github.com/martinezjavier/ldd3
box:Ubuntu 10.10 |2.6.35-27-generic #48-Ubuntu SMP i686 GNU/Linux
--thanks
[21028.412827] BUG: unable to handle kernel paging request at 00300d04
[21028.412832] IP: [] _copy_from_user+0x97/0x130
[21028.412839] *pde = 6fa0b067
[21028.412842] Oops: 0003 [#1] SMP
[21028.412845] last sysfs file:
/sys/devices/pci:00/:00:1c.3/:09:00.0/local_cpus
[21028.412849] Modules linked in: scull rfcomm binfmt_misc sco bnep l2cap
parport_pc ppdev dm_crypt snd_hda_codec_hdmi snd_hda_codec_idt snd_hda_intel
snd_hda_codec snd_hwdep snd_pcm snd_seq_midi snd_rawmidi snd_seq_midi_event
snd_seq lib80211_crypt_tkip btusb snd_timer snd_seq_device uvcvideo bluetooth
videodev dell_wmi wl(P) v4l1_compat psmouse serio_raw dell_wmi_aio
sparse_keymap dell_laptop dcdbas snd lib80211 soundcore snd_page_alloc lp
parport dm_raid45 xor i915 drm_kms_helper drm usb_storage intel_agp ahci
agpgart i2c_algo_bit video output libahci r8169 mii
[21028.412890]
[21028.412894] Pid: 8241, comm: dd Tainted: P2.6.35-27-generic
#48-Ubuntu 01HXXJ/Inspiron N5050
[21028.412897] EIP: 0060:[] EFLAGS: 00010216 CPU: 2
[21028.412900] EIP is at _copy_from_user+0x97/0x130
[21028.412902] EAX: 9f034959 EBX: 0200 ECX: 0200 EDX: 477efb2f
[21028.412905] ESI: 08e01000 EDI: 00300d04 EBP: c8b6bf1c ESP: c8b6bf10
[21028.412907] DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
[21028.412910] Process dd (pid: 8241, ti=c8b6a000 task=f71d2610
task.ti=c8b6a000)
[21028.412912] Stack:
[21028.412913] f9f26d00 0cc0 f9f26d14 c8b6bf64 f9f24d84 f9f2636f 022d
02e0
[21028.412920] <0> 0200 08b74600 0024 02e0 08b4 f247c2d8
08e01000 0200
[21028.412926] <0> 003d0900 0200 e677cc80 0200 08e01000 c8b6bf8c
c0218fc2 c8b6bf98
[21028.412933] Call Trace:
[21028.412940] [] ? scull_write+0x193/0x204 [scull]
[21028.412946] [] ? vfs_write+0xa2/0x190
[21028.412949] [] ? scull_write+0x0/0x204 [scull]
[21028.412953] [] ? sys_write+0x42/0x70
[21028.412958] [] ? syscall_call+0x7/0xb
[21028.412963] [] ? calibrate_delay_direct+0x5a/0xfb
[21028.412965] Code: 8b 1c 24 8b 7c 24 08 89 ec 5d c3 90 89 f0 31 f8 85 05 80
8e 81 c0 74 be 89 d9 8b 46 20 83 f9 43 76 04 8b 46 40 90 8b 06 8b 56 04 <89> 07
89 57 04 8b 46 08 8b 56 0c 89 47 08 89 57 0c 8b 46 10 8b
[21028.413001] EIP: [] _copy_from_user+0x97/0x130 SS:ESP 0068:c8b6bf10
[21028.413005] CR2: 00300d04
[21028.413009] ---[ end trace 3bd8365f04ad063d ]---
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Re: Getting Information from Multiple nodes
On Wed, 2011-11-16 at 18:00 +0530, Praveen kumar wrote: > Hi All, > I have a I2C chip driver,and there are two identical chips on > two different i2c bus. > I have registered the driver and initialized it and created two > nodes /dev/chip_0 and /dev/chip_1 > > If I open the node from user how will I make driver identify which > device to access .ie in the ioctl. So in your ioctl call you want to get the device structure right? If yes then have a look at scull/main.c file in scull folder at below location. git://github.com/martinezjavier/ldd3.git Basically you need to set private_data of filp at open time with device information and get the private_data from filp in ioctl. If you don't understand then just have a look at the file I mentioned. > > Am I clear ??? > > Praveen > > > ___ > Kernelnewbies mailing list > Kernelnewbies@kernelnewbies.org > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Questions about this patch: [PATCH] ARM: Use generic BUG() handler
https://lkml.org/lkml/2011/2/28/565
I have tested this patch on my system(linux 2.6.35-android) and it is
working
perfectly fine so wanted to understand this patch.Will this patch be
included in
mainline?
I have few question from this thread.As my understanding of assembly is
bit limited I would appreciate if someone can just say yes/no and probably
add
bit of words.
> This implementation uses an undefined instruction to implement BUG, and
> sets up
> a bug table containing the relevant information. Many version of gcc do
> not
> support %c properly for ARM (inserting a # when they shouldn't) so we work
> around this using distasteful macro magic.
This undefined instruction should cause data abort ?
> +#define BUG() _BUG(__FILE__, __LINE__, BUG_INSTR_VALUE)
> +#define _BUG(file, line, value) __BUG(file, line, value)
> +#define __BUG(__file, __line, __value) \
> +do { \
> + BUILD_BUG_ON(sizeof(struct bug_entry) != 12); \
> + asm volatile("1:\t" BUG_INSTR_TYPE #__value "\n" \
> + ".pushsection .rodata.str, \"aMS\", 1\n" \
> + "2:\t.asciz " #__file "\n" \
> + ".popsection\n" \
> + ".pushsection __bug_table,\"a\"\n" \
> + "3:\t.word 1b, 2b\n" \
> + "\t.hword " #__line ", 0\n" \
> + ".popsection"); \
> + unreachable(); \
> +} while (0)
Above piece of code i couldn't understand.As i understand this should do
same as
original BUG() definition plus it should print the function where BUG() had
originally
happened instead of "PC at _bug".I think in this code some
data(guess:function name
,line no) is pushed on the stack and then popped but how this data is
printed on console?
So kindly enlighten me on this piece of code or some pointers.Is there any
thread which
explains about kernel fault process?
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Re: Memory leak with dev_add_pack()
> Hi! > > On 21:22 Sun 23 Jan , anish kumar wrote: >> > The funny point is that buffer_head belongs to the filesystem >> > subsystem. >> > What >> > file systems are you using? Could it be that your code just triggers >> > the >> > memory leak, because data is logged to disk, e.g. to /var/log/kern.log >> > ? >> I did small experiment with your code.I removed all your logs which were >> getting >> logged in kernel buffers(kern.log).With this change i checked the >> "meminfo" >> and found that >> the memory leaking is almost same as compared to normal case(with no >> change >> in your code). >> >> > >> > I have tried your program on my virtual machine (2.6.28) and could see >> > any >> > leak, but maybe data is leaked very slowly... >> i confirm that data is leaking very slowly (below is the output i got on >> my >> ubuntu machine >> with removed logs from your code). >> >> $date >> Sun Jan 23 19:13:47 RET 2011 >> >> $ head -n5 /proc/meminfo >> MemTotal:1018172 kB >> MemFree: 373708 kB >> Buffers: 32232 kB >> Cached: 296004 kB >> SwapCached:0 kB >> >> $ date >> Sun Jan 23 19:15:03 RET 2011 >> >> $ head -n5 /proc/meminfo >> MemTotal:1018172 kB >> MemFree: 373584 kB >> Buffers: 32248 kB >> Cached: 296004 kB >> SwapCached:0 kB >> >> With logs enabled in your code i can see marginal increase in leaking >> memory. > > This small increase could easily be caused by background activity. Please > try > to reproduce this in single user mode with all file systems mounted > read-only > (use e.g. "mount -o remount,ro /") and no processes running except init > and > your shell. Then see if memory increase is both correlated to network > traffic > and reason of system crashes. If it takes too long, you can add e.g. > "mem=32M" to the kernel boot parameter list in the bootloader. Thanks for this suggestions. After persuading my kernel to use only 100M(with 32M system not booting,it is not vanilla kernel) of my physical memory and after installing your ko i tried to check meminfo and found that the claim made by you(.ko is leaking memory) may not be true as i can see in the output of /proc/meminfo,MemFree is sometimes increasing and sometimes decreasing(could be because of several other components). I can say with certainty that your ko looks fine to me after this testing. I couldn't see any panic happening in my system( system is running fine under such low memory). However i see that several other applications(xserv) is crashing because of out of memory which i think is fine. ps:I dont have vanilla kernel where i could have changed the intitialisation files to remount while booting and could have controlled the list of process running on the system. In android we are doing that in init.rc file need to check in ubuntu. > -Michi > -- > programing a layer 3+4 network protocol for mesh networks > see http://michaelblizek.twilightparadox.com > ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Memory leak with dev_add_pack()
> Hi! > > On 11:40 Sun 23 Jan , Spiro Trikaliotis wrote: > ... >> * On Sat, Jan 22, 2011 at 08:18:05AM +0100 Michael Blizek wrote: > ... >> > - Which user grows is /proc/slabinfo? (If this file is emply or does >> > not >> > exist, you may meed to recompile the kernel to use slab instead of >> > sl[b-z]b) >> >> Thank you for the pointer, it might help. >> >> The objects which have changed the most on a mildly loaded network are: >> >> 25000 buffer_head >> 5000 dentry >> 5000 ext3_inode_cache >> 5000 size-64 >> >> The number if the number of more active object after approx. 20h of >> letting it run on the mildly loaded network. >> >> Note that the ext3_inode_cache might have grown because I was regularly >> writing a new log file from slabinfo (slabinfo --once > slabinfo.`date >> +...`) >> >> Thus, I would expect I am leaking buffer_head. > > The funny point is that buffer_head belongs to the filesystem subsystem. > What > file systems are you using? Could it be that your code just triggers the > memory leak, because data is logged to disk, e.g. to /var/log/kern.log ? I did small experiment with your code.I removed all your logs which were getting logged in kernel buffers(kern.log).With this change i checked the "meminfo" and found that the memory leaking is almost same as compared to normal case(with no change in your code). > > I have tried your program on my virtual machine (2.6.28) and could see any > leak, but maybe data is leaked very slowly... i confirm that data is leaking very slowly (below is the output i got on my ubuntu machine with removed logs from your code). $date Sun Jan 23 19:13:47 RET 2011 $ head -n5 /proc/meminfo MemTotal:1018172 kB MemFree: 373708 kB Buffers: 32232 kB Cached: 296004 kB SwapCached:0 kB $ date Sun Jan 23 19:15:03 RET 2011 $ head -n5 /proc/meminfo MemTotal:1018172 kB MemFree: 373584 kB Buffers: 32248 kB Cached: 296004 kB SwapCached:0 kB With logs enabled in your code i can see marginal increase in leaking memory. I can defintely see the memory leaking with your ko and will investigate further as to the reason. Hopefully kmemleak will lead us somewhere. > > -Michi > -- > programing a layer 3+4 network protocol for mesh networks > see http://michaelblizek.twilightparadox.com > > > ___ > Kernelnewbies mailing list > Kernelnewbies@kernelnewbies.org > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
