Re: LTTng 0.193 fixes RT kernel support

From: naresh kamboju <naresh.kernel@gmail.com>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org,
	Steven Rostedt <rostedt@goodmis.org>,
	ltt-dev@lists.casi.polymtl.ca,
	Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>
Subject: Re: LTTng 0.193 fixes RT kernel support
Date: Tue, 23 Feb 2010 21:05:08 +0530	[thread overview]
Message-ID: <f5a7b3811002230735p2eb90904l33e8090ade66fc14@mail.gmail.com> (raw)
In-Reply-To: <20100223123016.GA12857@Krystal>

On Tue, Feb 23, 2010 at 6:00 PM, Mathieu Desnoyers
<mathieu.desnoyers@efficios.com> wrote:
> * naresh kamboju (naresh.kernel@gmail.com) wrote:
>> On Mon, Feb 22, 2010 at 9:07 PM, naresh kamboju <naresh.kernel@gmail.com> wrote:
>> > On Thu, Feb 18, 2010 at 4:38 AM, Mathieu Desnoyers
>> > <mathieu.desnoyers@efficios.com> wrote:
>> >> * naresh kamboju (naresh.kernel@gmail.com) wrote:
>> >>> On Tue, Feb 16, 2010 at 10:35 PM, Mathieu Desnoyers <compudj@krystal.dyndns.org> wrote:
>> >>> > Oh, right. Thanks for the explanation. I'll look into moving LTTng to a
>> >>> > saner del_timer_sync() scheme to delete the timers.
>>
>> patch trace-clock-32-to-64-use-del-timer-sync.patch is causing above
>> problem on SMP.
>>
>> with out this patch on SMP reported the previous bug as BUG: sleeping
>> function called from invalid context at kernel/rtmutex.c:685
>>
>> However, i'll investigate.
>
> Hrm, we should turn the arch/{arm/mach-omap2,x86/kernel}/trace-clock.c:
> trace_clock_lock into a mutex, and kernel/trace/trace-clock-32-to-64.c:
> synthetic_tsc_lock into a mutex too.

I have modified kernel/trace/trace-clock-32-to-64.c spin_lock to
mutex_lock to all the calls

-static DEFINE_SPINLOCK(synthetic_tsc_lock);
+static DEFINE_MUTEX(synthetic_tsc_lock);

-       spin_lock(&synthetic_tsc_lock);
+       mutex_lock(&synthetic_tsc_lock);

for arch/{arm/mach-omap2/kernel}/trace-clock.c is already modified as
above from the patch
omap-trace-clock-fix-mutex.patch
from LTTng patches 02-Feb-2009.
this patch was prepared by you to fix
BUG: sleeping function called from invalid context at kernel/mutex.c:207.

Still reporting same bug at my end :-(

let me try in all possible ways.

Best regards
Naresh Kamboju
>
> I used a spinlock previously on ARM because it was called from power
> management resume, but now that the data structures touched by this code
> path are per-cpu, this lock is not taken there, so it should be OK to
> turn it into a mutex.
>
> Can you try that and tell me if that fixes your issues ?
>
> Thanks,
>
> Mathieu
>
>>
>> Best regards,
>> Naresh Kamboju
>> >> Thanks,
>> >>
>> >> Mathieu
>> >>
>> >> --
>> >> Mathieu Desnoyers
>> >> OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
>> >>
>> >
>>
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>
> --
> Mathieu Desnoyers
> OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
>