Re: How to check if my kernel driver is leaking memory
On Sun, 09 Mar 2014 22:14:24 -0700, m silverstri said: I am developing a kernel driver. What should I test to make sure my kernel driver is not leaking memory? 1) The brute force method - just add lots of printk's that have allocating 25-byte frobozz struct and freeing 25-byte frobozz struct and make sure they match up. 2) kmemleak. 1. under normal operation (when applications open and close my driver properly) 2. in error situation (when application open my driver and then it crashes without close my driver property) Case (2) shouldn't happen, as even if a program crashes the kernel *should* be invoking the cleanup of open files at process termination. A more common cause of memory leaks is for an open() or read/write/ioctl() path to allocate N chunks of memory, hit an error, and return after having cleaned up only N-1 of the chunks. This is part of why most kernel code uses a 'goto error' structure with only one return; at the end of the function. pgpXDk8WMFJrj.pgp Description: PGP signature ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Kernelnewbies Digest, Vol 40, Issue 16
Ok they are gone part of the order did not come in. Though it's working and the inside is setup very pretty. You can adjust the stones and sand there is extra or both on the bed. --- Please excuse If this message is overly terse. It is because it is being sent on my iPad. On Mar 10, 2014, at 12:00 PM, kernelnewbies-requ...@kernelnewbies.org wrote: Send Kernelnewbies mailing list submissions to kernelnewbies@kernelnewbies.org To subscribe or unsubscribe via the World Wide Web, visit http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies or, via email, send a message with subject or body 'help' to kernelnewbies-requ...@kernelnewbies.org You can reach the person managing the list at kernelnewbies-ow...@kernelnewbies.org When replying, please edit your Subject line so it is more specific than Re: Contents of Kernelnewbies digest... Today's Topics: 1. How to check if my kernel driver is leaking memory (m silverstri) 2. Re: How to check if my kernel driver is leaking memory (valdis.kletni...@vt.edu) -- Message: 1 Date: Sun, 9 Mar 2014 22:14:24 -0700 From: m silverstri michael.j.silvers...@gmail.com Subject: How to check if my kernel driver is leaking memory To: kernelnewbies kernelnewbies@kernelnewbies.org Message-ID: cabmudhtc8c9hbt8qas1twyc0vncy1ywtk3i2xyyvo6momy-...@mail.gmail.com Content-Type: text/plain; charset=ISO-8859-1 Hi, I am developing a kernel driver. What should I test to make sure my kernel driver is not leaking memory? 1. under normal operation (when applications open and close my driver properly) 2. in error situation (when application open my driver and then it crashes without close my driver property) How can I find out the memory usage used by my driver? so that I can monitor it over time. Thank you. -- Message: 2 Date: Mon, 10 Mar 2014 09:58:39 -0400 From: valdis.kletni...@vt.edu Subject: Re: How to check if my kernel driver is leaking memory To: m silverstri michael.j.silvers...@gmail.com Cc: kernelnewbies kernelnewbies@kernelnewbies.org Message-ID: 167370.1394459...@turing-police.cc.vt.edu Content-Type: text/plain; charset=us-ascii On Sun, 09 Mar 2014 22:14:24 -0700, m silverstri said: I am developing a kernel driver. What should I test to make sure my kernel driver is not leaking memory? 1) The brute force method - just add lots of printk's that have allocating 25-byte frobozz struct and freeing 25-byte frobozz struct and make sure they match up. 2) kmemleak. 1. under normal operation (when applications open and close my driver properly) 2. in error situation (when application open my driver and then it crashes without close my driver property) Case (2) shouldn't happen, as even if a program crashes the kernel *should* be invoking the cleanup of open files at process termination. A more common cause of memory leaks is for an open() or read/write/ioctl() path to allocate N chunks of memory, hit an error, and return after having cleaned up only N-1 of the chunks. This is part of why most kernel code uses a 'goto error' structure with only one return; at the end of the function. -- next part -- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 848 bytes Desc: not available Url : http://lists.kernelnewbies.org/pipermail/kernelnewbies/attachments/20140310/3ae80b6f/attachment-0001.bin -- ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies End of Kernelnewbies Digest, Vol 40, Issue 16 * ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
PROCESS PRIORITY
I am new to Linux kernel and I have got confused . Please can anyone give answer to my questions : Q1 - Is static priority of a thread changes or not ? If changes then how it changes ? Q2 - What is the default value of static priority and dynamic priority for a process and thread in Linux kernel ? Q3 - What is the initial value of static priority and dynamic priority for a newly created thread and process? Q4 - When we talk about the priority of a process or thread (incrementing / decrementing priority , setting priority etc. ) , then which priority we are referring , is it static priority or dynamic priority ? ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Release DMA Memory
I have a kernel module that communicates to a PCI device via DMA. The module allocates the shared memory using dma_alloc_coherent(). When the module is unloaded, a call to dma_free_coherent() is executed. My question is, since the DMA memory is not explicitly zeroed before deallocation, is there a chance that the PCI device could still read (non-zeroed data) and act upon the DMA memory after the module unloads and calls dma_free_coherent()? Thanks! -Matt ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
how to rmmod module
Hi, when u insmod module,yours PC maybe dump. and u can not rmmod your module except reboot. i want to know has other ways to solution module loader error? ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Release DMA Memory
On Mar 11, 2014 7:57 AM, Matt Davis mattdav...@gmail.com wrote: I have a kernel module that communicates to a PCI device via DMA. The module allocates the shared memory using dma_alloc_coherent(). When the module is unloaded, a call to dma_free_coherent() is executed. My question is, since the DMA memory is not explicitly zeroed before deallocation, is there a chance that the PCI device could still read (non-zeroed data) and act upon the DMA memory after the module unloads and calls dma_free_coherent()? Ideally you should stop the device before freeing the memory. If device is allowed to run and access the memory after memory is free this may leads to memory coruption that would be hard to debug. Thanks! -Matt -Chetan ___ 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 rmmod module
I guess you'd better figure out why the dump occur firstly. 2014-03-11 10:30 GMT+08:00 于运超 wuyaa...@gmail.com: Hi, when u insmod module,yours PC maybe dump. and u can not rmmod your module except reboot. i want to know has other ways to solution module loader error? ___ 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: A new way to dive into the kernel!
Hello All, Have you guys getting your assignment's ? Regards Sanjeev Sharma On Wed, Mar 5, 2014 at 10:50 AM, Mallesh Koujalagi mallesh.koujalagi.sandi...@gmail.com wrote: Good info, thanks for sharing On Tue, Mar 4, 2014 at 8:38 PM, Amit Saha amitsaha...@gmail.com wrote: On Wed, Mar 5, 2014 at 2:19 PM, Mandeep Sandhu mandeepsandhu@gmail.com wrote: Came across this in Greg (KH)s G+ feed. http://eudyptula-challenge.org/ Thought I'd share it here too in case someone missed it. Looks like a fun and interesting way to start off doing stuff in the kernel! Interesting! Thanks for sharing. -- http://echorand.me ___ 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
Does register_chrdev function make device file under /dev ?
Hi,
This should be a basic question.
Does the regisetr_chrdev function make the device file under /dev directory?
I am running linux on our embedded system and inside vcs_init, register_chrdev
is called as below.
int __init vcs_init(void)
{
unsigned int i;
if (register_chrdev(VCS_MAJOR, vcs, vcs_fops))
panic(unable to get major %d for vcs device, VCS_MAJOR);
I can see the function is returning ok but I don't see any vcs* file under /dev.
Does it only register the device on /sys or /proc directory and not under /dev?
Thanks in advance.
Chan
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Re: Does register_chrdev function make device file under /dev ?
On Mar 10, 2014, at 10:25 PM, 김찬 c...@etri.re.kr wrote:
Hi,
This should be a basic question.
Does the regisetr_chrdev function make the device file under /dev directory?
I am running linux on our embedded system and inside vcs_init,
register_chrdev is called as below.
int __init vcs_init(void)
{
unsigned int i;
if (register_chrdev(VCS_MAJOR, vcs, vcs_fops))
panic(unable to get major %d for vcs device, VCS_MAJOR);
I can see the function is returning ok but I don't see any vcs* file under
/dev.
Does it only register the device on /sys or /proc directory and not under
/dev?
Thanks in advance.
Chan
You have to create a device file using 'mknod'
Ex: mknod -m 666 /dev/vcs c major no minor no
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Re: A new way to dive into the kernel!
Yes. Just remember to send a plain text mail. HTH, -mandeep On Tue, Mar 11, 2014 at 10:36 AM, sanjeev sharma sanjeevsharmae...@gmail.com wrote: Hello All, Have you guys getting your assignment's ? Regards Sanjeev Sharma On Wed, Mar 5, 2014 at 10:50 AM, Mallesh Koujalagi mallesh.koujalagi.sandi...@gmail.com wrote: Good info, thanks for sharing On Tue, Mar 4, 2014 at 8:38 PM, Amit Saha amitsaha...@gmail.com wrote: On Wed, Mar 5, 2014 at 2:19 PM, Mandeep Sandhu mandeepsandhu@gmail.com wrote: Came across this in Greg (KH)s G+ feed. http://eudyptula-challenge.org/ Thought I'd share it here too in case someone missed it. Looks like a fun and interesting way to start off doing stuff in the kernel! Interesting! Thanks for sharing. -- http://echorand.me ___ 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
