From: Thomas Gleixner <tglx@linutronix.de>
To: Mathieu Desnoyers <compudj@krystal.dyndns.org>
Cc: Steven Rostedt <rostedt@goodmis.org>,
ltt-dev@lists.casi.polymtl.ca, Ingo Molnar <mingo@elte.hu>,
linux-kernel@vger.kernel.org
Subject: Re: [ltt-dev] LTTng0.158 Linux-2629-RT kernel BUG: sleeping function called from invalid context at kernel/rtmutex.c:685
Date: Tue, 16 Feb 2010 18:01:49 +0100 (CET) [thread overview]
Message-ID: <alpine.LFD.2.00.1002161757050.2811@localhost.localdomain> (raw)
In-Reply-To: <20100216164744.GA25115@Krystal>
On Tue, 16 Feb 2010, Mathieu Desnoyers wrote:
> > The function is called from an IPI. That's a LTTNG problem, not a RT one.
>
> I use del_timer in IPI to delete lttng per-cpu timers on all CPUs. I
> have to do this because timers created with add_timer_on are documented
> to be incompatible with del_timer_sync():
>
> * Synchronization rules: Callers must prevent restarting of the timer,
> * otherwise this function is meaningless. It must not be called from
> * interrupt contexts. The caller must not hold locks which would prevent
> * completion of the timer's handler. The timer's handler must not call
> * add_timer_on(). Upon exit the timer is not queued and the handler is
> * not running on any CPU.
Errm. The documentation says:
"The timer's handler must not call add_timer_on()."
It's not talking about a timer which was initialized with
add_timer_on().
And your per cpu timer handlers have no requirement to call
add_timer_on() simply because add/mod_timer() is requeueing the timer
on the same cpu on which the handler runs.
So the IPI is just a solution for a non existing problem.
Thanks,
tglx
next prev parent reply other threads:[~2010-02-16 17:02 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-16 15:17 LTTng0.158 Linux-2629-RT kernel BUG: sleeping function called from invalid context at kernel/rtmutex.c:685 naresh kamboju
2010-02-16 16:24 ` Steven Rostedt
2010-02-16 16:30 ` Thomas Gleixner
2010-02-16 16:47 ` [ltt-dev] " Mathieu Desnoyers
2010-02-16 17:01 ` Thomas Gleixner [this message]
2010-02-16 17:05 ` Mathieu Desnoyers
2010-02-17 10:36 ` naresh kamboju
2010-02-17 23:08 ` [ltt-dev] LTTng 0.193 fixes RT kernel support Mathieu Desnoyers
2010-02-22 15:37 ` naresh kamboju
2010-02-23 11:29 ` naresh kamboju
2010-02-23 12:30 ` Mathieu Desnoyers
2010-02-23 15:35 ` naresh kamboju
2010-02-23 15:52 ` Mathieu Desnoyers
2010-02-24 16:01 ` naresh kamboju
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=alpine.LFD.2.00.1002161757050.2811@localhost.localdomain \
--to=tglx@linutronix.de \
--cc=compudj@krystal.dyndns.org \
--cc=linux-kernel@vger.kernel.org \
--cc=ltt-dev@lists.casi.polymtl.ca \
--cc=mingo@elte.hu \
--cc=rostedt@goodmis.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).