Re: [PATCH -tip ] [BUGFIX] kprobes: Fix a double lock bug ofkprobe_mutex

From: Tejun Heo
Date: Thu Apr 18 2013 - 14:17:17 EST


On Thu, Apr 18, 2013 at 06:33:18PM +0900, Masami Hiramatsu wrote:
> Fix a double locking bug caused when debug.kprobe-optimization=0.
> While the proc_kprobes_optimization_handler locks kprobe_mutex,
> wait_for_kprobe_optimizer locks it again and that causes a double lock.
> To fix the bug, this introduces different mutex for protecting
> sysctl parameter and locks it in proc_kprobes_optimization_handler.
> Of course, since we need to lock kprobe_mutex when touching kprobes
> resources, that is done in *optimize_all_kprobes().
>
> This bug was from ad72b3bea744b4db01c89af0f86f3e8920d354df
>
> Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: Tejun Heo <tj@xxxxxxxxxx>
> Cc: Ananth N Mavinakayanahalli <ananth@xxxxxxxxxx>
> Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>

Oops,

Acked-by: Tejun Heo <tj@xxxxxxxxxx>

Thanks.

--
tejun
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