Re: [PATCH] sched/clock: prevent tracing recursion in sched_clock_cpu()

[Peter Zijlstra]

On Thu, Mar 06, 2014 at 02:25:28PM +0900, Fernando Luis Vázquez Cao wrote:
> From: Fernando Luis Vazquez Cao <fernando@xxxxxxxxxxxxx>
> 
> Prevent tracing of preempt_disable/enable() in sched_clock_cpu().
> When CONFIG_DEBUG_PREEMPT is enabled, preempt_disable/enable() are
> traced and this causes trace_clock() users (and probably others) to
> go into an infinite recursion. Systems with a stable sched_clock()
> are not affected.
> 
> This problem is similar to that fixed by upstream commit 95ef1e52922
> ("KVM guest: prevent tracing recursion with kvmclock").
> 
> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
> Signed-off-by: Fernando Luis Vazquez Cao <fernando@xxxxxxxxxxxxx>

Thanks!
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