Hi Pranay, This code logs the messages without problem if I don't stress it, so I suppose you can. If you want I will commit tomorrow my changes on github and I will send you the url to have a look. Cheers, Panos On May 2, 2012, at 10:31 PM, Pranay Kumar Srivastava wrote:
You mentioned your code is atomic. Are you certain that you can do a sock_sendmsg from a non process context? I believe you can't do that from a non process context cuz sock_sendmsg-->udp_sendmsg for DGRAM and i think that assumes you are in process context.
________________________________________ From: kernelnewbies-bounces@kernelnewbies.org [kernelnewbies-bounces@kernelnewbies.org] On Behalf Of kernelnewbies-request@kernelnewbies.org [kernelnewbies-request@kernelnewbies.org] Sent: Wednesday, May 02, 2012 9:30 PM To: kernelnewbies@kernelnewbies.org Subject: Kernelnewbies Digest, Vol 18, Issue 2
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Today's Topics:
1. please report distros with CONFIG_DYNAMIC_DEBUG, using ddebug_query= boot param (Jim Cromie) 2. Re: immutable wiki? (michi1@michaelblizek.twilightparadox.com) 3. Re: immutable wiki? (Bill Traynor) 4. Crash when sending a lot of messages through a unix socket (Panagiotis Sakkos)
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Message: 1 Date: Tue, 1 May 2012 12:36:04 -0600 From: Jim Cromie <jim.cromie@gmail.com> Subject: please report distros with CONFIG_DYNAMIC_DEBUG, using ddebug_query= boot param To: kernelnewbies <kernelnewbies@kernelnewbies.org> Message-ID: <CAJfuBxw8aYimAU7kO42vh_e-zZBNSkw9Hd8Dx2tFCOWL4ueVgQ@mail.gmail.com> Content-Type: text/plain; charset=ISO-8859-1
hi all,
Ive been asked whether ddebug_query= boot param is used in any distros, I think the question seeks to determine a good deprecation schedule for it (its been obsoleted by dyndbg= in driver-core-next)
Would you all be so kind as to check your favorite distros, and report the ones that have one or both ?
Ubuntu 12.04 LTS lacks it:
jimc@chumly:~/projects/lx/linux-2.6$ grep DYNAMIC_DEBUG /boot/config* /boot/config-3.0.0-17-generic:# CONFIG_DYNAMIC_DEBUG is not set /boot/config-3.2.0-24-generic:# CONFIG_DYNAMIC_DEBUG is not set
Voyage linux also lacks it, (also debian based)
Fedora-16 has config option:
$ uname -a Linux groucho.jimc.earth 3.3.2-6.fc16.x86_64 #1 SMP Sat Apr 21 12:43:20 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux $ grep DYNAMIC_DEBUG /boot/config-3.3.* /boot/config-3.3.1-5.fc16.x86_64:CONFIG_DYNAMIC_DEBUG=y /boot/config-3.3.2-1.fc16.x86_64:CONFIG_DYNAMIC_DEBUG=y /boot/config-3.3.2-6.fc16.x86_64:CONFIG_DYNAMIC_DEBUG=y
but its not used by default. I have modified my grub defaults:
$ grep ddebug_query /etc/default/grub GRUB_CMDLINE_LINUX='quiet rhgb loglevel=8 ddebug_query="module params +p" dynamic_debug.verbose=1 nouveau.dyndbg nouveau.force_post=1 it87.dyndbg=+p nouveau.perflvl_wr=7777'
FYI, the above usage will eventually be unsupported, it can be replaced in driver-core-next by either of:
dyndbg="module params +p" params.dyndbg=+p params.dyndbg # defaults to +p
the 2nd, 3rd forms also work for loadable modules (though params isnt one of them)
thanks in advance Jim
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Message: 2 Date: Wed, 2 May 2012 12:52:38 +0200 From: michi1@michaelblizek.twilightparadox.com Subject: Re: immutable wiki? To: Bill Traynor <wmat@alphatroop.com> Cc: kernelnewbies@kernelnewbies.org Message-ID: <20120502105237.GA2229@grml> Content-Type: text/plain; charset=us-ascii
Hi!
On 09:29 Tue 01 May , Bill Traynor wrote:
I have an Editor account for the kernelnewbies.org wiki, but all pages are currently immutable. Was the wiki made read-only at some point?
You must be on http://kernelnewbies.org/EditorsGroup to make changes. This was made for spam procection. Everybody who is on the list can add you. What is your username in the wiki?
-Michi -- programing a layer 3+4 network protocol for mesh networks see http://michaelblizek.twilightparadox.com
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Message: 3 Date: Wed, 2 May 2012 08:06:36 -0400 From: Bill Traynor <wmat@alphatroop.com> Subject: Re: immutable wiki? To: michi1@michaelblizek.twilightparadox.com Cc: kernelnewbies@kernelnewbies.org Message-ID: <CAGfZjq69kO91rbiG8R5jTUmRDq3ZJRjp_oTLqS8wji1M=1NJ-Q@mail.gmail.com> Content-Type: text/plain; charset=ISO-8859-1
On Wed, May 2, 2012 at 6:52 AM, <michi1@michaelblizek.twilightparadox.com> wrote:
Hi!
On 09:29 Tue 01 May ? ? , Bill Traynor wrote:
I have an Editor account for the kernelnewbies.org wiki, but all pages are currently immutable. ?Was the wiki made read-only at some point?
You must be on http://kernelnewbies.org/EditorsGroup to make changes. This was made for spam procection. Everybody who is on the list can add you. What is your username in the wiki?
Thanks Michael, Rik already fixed it for me.
? ? ? ?-Michi -- programing a layer 3+4 network protocol for mesh networks see http://michaelblizek.twilightparadox.com
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Message: 4 Date: Wed, 2 May 2012 13:43:41 +0000 From: Panagiotis Sakkos <panos.sakkos@cern.ch> Subject: Crash when sending a lot of messages through a unix socket To: "kernelnewbies@kernelnewbies.org" <kernelnewbies@kernelnewbies.org> Message-ID: <A1F86B12A2E22C4CB3164ECFFD1C54DB08EC9407@PLOXCHG03.cern.ch> Keywords: CERN SpamKiller Note: -50 Content-Type: text/plain; charset="iso-8859-1"
Hi,
I am trying to log information from within the kernel with the use of a unix socket (/dev/log). My code is a kprobe handler, so while executing I am atomic and uninterrupted. The crashes begin when I do stress tests against my module, so i.e. more than 50 logs per second. The crash messages I get every time are different (from NULL reference, unable to handle page request etc), so I suppose that something is overwritten and this leads to the crash.
I don't want to post the code here because it ~100 LOC but these are my steps:
Initialization: call sock_create_kern, with PF_UNIX, SOCK_DGRAM, 0 and the address of my socket, then I memset to 0 my sockaddr_un variable and then I set its sun_family to PF_UNIX and copy the "/dev/log" string to sun_path
Logging: I have the message that I want to log in variable called buffer and its length in variable called message_length, I set the msg_name of the msghdr to the address of my sockaddr_un variable, than the msn_namelen to sizeof(sockadrr_un), the msg_iov to an iovec variable which contains the buffer and the message_length values, msg_iovlen to 1 and msg_control, msg_controllen to 0. Then I set the fs to KERNEL_DS, call sock_sendmsg with parameters my socket, the address of my msghdr and the message_length and then I restore the fs that there was before setting it to KERNEL_DS.
Please note that my socket, sockadd_un and my buffer are static variables. Also I always use the socket which is initialized once in the Initialization state (function).
Do you see any "bad practice" or something that could lead to crashes when stressing with a lot of messages the socket?
Thank you in advance! Panos -- http://www.cern.ch/psakkos