Re: Should I do anything about this warning?
On Wed, Oct 08, 2014 at 11:33:57AM +0200, Kristof Provost wrote: > On 2014-10-08 12:43:58 (+0530), Sagar Padhye wrote: > > I am new at kernel programming. I have written a driver for a custom > > device, running on arm board. It works well (for last few months). I > > happen to look at kernel logs and I seen, > > > > [231250.899146] WARNING: at kernel/workqueue.c:1953 > > process_one_work+0x398/0x52c() > > > You triggered a warning in the code. Yes, I got that > > The device is still working after this. No issues in operation. I am > > just sceptical about analyzing this issue? Do I need to check more? If > > yes how? with this trace? > > > Yes, this indicates a potential problem. The issue is not reproducible. Haven't seen in over 6 months. And the module is working just fine after the log. Is there a way I can get more info on this e.g. more stacktrace that will end up in module's work function (if this occurs again)? > You start my looking at line 1953 in kernel/workqueue.c, where you'll > see which specific warning you're triggering. > > It's probably this one: > > /* ensure we're on the correct CPU */ > >WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) && > > raw_smp_processor_id() != pool->cpu); They are, 1952 WARN_ON_ONCE(!(worker->flags & (WORKER_UNBOUND | WORKER_REBIND)) && 1953 raw_smp_processor_id() != gcwq->cpu); But I am not sure what they signify :( Thanks, Sagar ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Should I do anything about this warning?
Hi, I am new at kernel programming. I have written a driver for a custom device, running on arm board. It works well (for last few months). I happen to look at kernel logs and I seen, [231250.894334] [ cut here ] [231250.899146] WARNING: at kernel/workqueue.c:1953 process_one_work+0x398/0x52c() [231250.906491] Modules linked in: bcmdhd cfg80211 [231250.911885] [] (unwind_backtrace+0x0/0x144) from [] (dump_stack+0x20/0x24) [231250.920672] [] (dump_stack+0x20/0x24) from [] (warn_slowpath_common+0x5c/0x74) [231250.929757] [] (warn_slowpath_common+0x5c/0x74) from [] (warn_slowpath_null+0x2c/0x34) [231250.939581] [] (warn_slowpath_null+0x2c/0x34) from [] (process_one_work+0x398/0x52c) [231250.949232] [] (process_one_work+0x398/0x52c) from [] (rescuer_thread+0x184/0x230) [231250.958708] [] (rescuer_thread+0x184/0x230) from [] (kthread+0xac/0xb4) [231250.967236] [] (kthread+0xac/0xb4) from [] (kernel_thread_exit+0x0/0x8) [231250.975755] ---[ end trace 9f9c2187c0bee21b ]--- The device is still working after this. No issues in operation. I am just sceptical about analyzing this issue? Do I need to check more? If yes how? with this trace? Thanks, Sagar ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: [PATCH] FIXED sparse warning : drivers/cpuidle/cpuidle.c:27:1: warning: symbol 'cpuidle_dev' was not declared. Should it be static?
> > I checked that cpuidle_devices is only being used in cpuidle.c - hence > > thought that it can be made static and be removed from header. > > "cpuidle_devices" is actually used in drivers/cpuidle/coupled.c as well > so this breaks the build. Darn! I forgot 'clean build' part. sorry. > Even for "cpuidle_dev" the patch isn't right. It doesn't fix the > warning, for me. The DEFINE_PER_CPU() macro defines several variables > actually. Per CPU variables are a bit complicated and they have to have > globally unique names. So just ignore the Sparse warning for per CPU > variables. > Ok, let me look at my sparse log once again, will pick some other problem (any suggestions?) > There are several other "process" problems with the patch submission. > > 1) Incorrect subject. It should be: > [PATCH] cpuidle: make a variable static > >This is based on `git log --oneline drivers/cpuidle/cpuidle.c` >output. > > 2) No blank line between subject and body of commit message. > 3) Line wrap the body of the email at 72 characters. > 4) No Signed-off-by line. > Ok, will keep this in mind Thanks and Regards, Sagar ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
[PATCH] FIXED sparse warning : drivers/cpuidle/cpuidle.c:27:1: warning: symbol 'cpuidle_dev' was not declared. Should it be static?
---
This is the first (and minor) patch I am sending out, hope this is ok. I
checked that cpuidle_devices is only being used in cpuidle.c - hence thought
that it can be made static and be removed from header.
drivers/cpuidle/cpuidle.c | 4 ++--
include/linux/cpuidle.h | 1 -
2 files changed, 2 insertions(+), 3 deletions(-)
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index d75040d..4826506 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -23,8 +23,8 @@
#include "cpuidle.h"
-DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
-DEFINE_PER_CPU(struct cpuidle_device, cpuidle_dev);
+static DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
+static DEFINE_PER_CPU(struct cpuidle_device, cpuidle_dev);
DEFINE_MUTEX(cpuidle_lock);
LIST_HEAD(cpuidle_detected_devices);
diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
index 781addc..96c8ed8 100644
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -83,7 +83,6 @@ struct cpuidle_device {
#endif
};
-DECLARE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
/**
* cpuidle_get_last_residency - retrieves the last state's residency time
--
1.8.1.2
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Re: I2C: kernel & userspace drivers : using i2c-stub
I tried to use '*mknod* /dev/i2c-*0 c 89 0' and then tried to use the device. but still when I try to use device it gives IO error (so I concluded, I created incorrect device)* On Mon, Apr 22, 2013 at 7:41 PM, anish singh wrote: > does I2c-stub create the /dev node?If it is not creating then you > have to do it yourself. > > > On Mon, Apr 22, 2013 at 5:11 PM, Sagar Padhye wrote: > >> Hi, >> >> [USING : Ubuntu 12.04 LTS] >> >> I am trying to learn I2C subsystem. I havent found much of well >> documented things that can help a newbie on google. I just chose to read >> the linux kernel documentation txts. >> >> I read the way kernel can interact with i2c through both SMBus calls & >> raw file op calls (ioctl, read, write). It looks good till that point. >> >> The doc also tells about i2c stub. which can be used as follows: >> 1. load the i2c module >> 2. use i2cset (from the i2c-tools project) to pre-load some data >> 3. load the target chip driver module >> 4. observe its behavior in the kernel log >> >> I was able to achieve just the 1st step here. I loaded the module >> successfully. >> $ sudo modprobe i2c-stub chip_addr=0x023 >> >> I got following Kern msg >> $dmesg >> ... >> [658.071706] i2c-stub: Virtual chip at 0x23 >> >> So I believe that step 1 is clear. >> >> in second step I have no idea how to provide needed inputs to command >> -> >> Usage : i2cset [-f] [-y] [-m mask] I2CBUS CHIP-ADDRESS DATA-ADDRESS >> [VALUE] [MODE] >> I tried to give I2CBUS = 0, Chip addr = 0x23 & data addr=0 but it gives >> error >> Error : Could not open file '/dev/i2c-0' or '/dev/i2c/0' : No such file >> or directory >> >> There is no file at all created in /dev corrosponding to this device. >> >> Any idea how to use i2c properly? Is this an ubuntu only problem? Can >> anybody provide a good tutorial like thing to learn about i2c kernel & >> userspace driver programming? >> >> -- >> Thanks and Regards, >> Sagar >> >> ___ >> 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 > > -- Thanks and Regards, Sagar ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
I2C: kernel & userspace drivers : using i2c-stub
Hi, [USING : Ubuntu 12.04 LTS] I am trying to learn I2C subsystem. I havent found much of well documented things that can help a newbie on google. I just chose to read the linux kernel documentation txts. I read the way kernel can interact with i2c through both SMBus calls & raw file op calls (ioctl, read, write). It looks good till that point. The doc also tells about i2c stub. which can be used as follows: 1. load the i2c module 2. use i2cset (from the i2c-tools project) to pre-load some data 3. load the target chip driver module 4. observe its behavior in the kernel log I was able to achieve just the 1st step here. I loaded the module successfully. $ sudo modprobe i2c-stub chip_addr=0x023 I got following Kern msg $dmesg ... [658.071706] i2c-stub: Virtual chip at 0x23 So I believe that step 1 is clear. in second step I have no idea how to provide needed inputs to command -> Usage : i2cset [-f] [-y] [-m mask] I2CBUS CHIP-ADDRESS DATA-ADDRESS [VALUE] [MODE] I tried to give I2CBUS = 0, Chip addr = 0x23 & data addr=0 but it gives error Error : Could not open file '/dev/i2c-0' or '/dev/i2c/0' : No such file or directory There is no file at all created in /dev corrosponding to this device. Any idea how to use i2c properly? Is this an ubuntu only problem? Can anybody provide a good tutorial like thing to learn about i2c kernel & userspace driver programming? -- Thanks and Regards, Sagar ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
