Re: + sched-fix-raciness-in-runqueue_is_locked.patch added to -mmtree

[Steven Rostedt]

On Sat, 2009-09-19 at 11:55 -0700, akpm@xxxxxxxxxxxxxxxxxxxx wrote:
> The patch titled
>      sched(): fix raciness in runqueue_is_locked()
> has been added to the -mm tree.  Its filename is
>      sched-fix-raciness-in-runqueue_is_locked.patch
> 
> Before you just go and hit "reply", please:
>    a) Consider who else should be cc'ed
>    b) Prefer to cc a suitable mailing list as well
>    c) Ideally: find the original patch on the mailing list and do a
>       reply-to-all to that, adding suitable additional cc's
> 
> *** Remember to use Documentation/SubmitChecklist when testing your code ***
> 
> See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
> out what to do about this
> 
> The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
> 
> ------------------------------------------------------
> Subject: sched(): fix raciness in runqueue_is_locked()
> From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> 
> runqueue_is_locked() is unavoidably racy due to a poor interface design. 
> It does
> 
> 	cpu = get_cpu()
> 	ret = some_perpcu_thing(cpu);
> 	put_cpu(cpu);
> 	return ret;
> 
> Its return value is unreliable.
> 
> Fix.
> 
> Cc: Ingo Molnar <mingo@xxxxxxx>


Acked-by: Steven Rostedt <rostedt@xxxxxxxxxxx>


> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> ---
> 


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