From: Li Zefan <lizefan@huawei.com>
To: John Stultz <john.stultz@linaro.org>
Cc: lkml <linux-kernel@vger.kernel.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Steven Rostedt <rostedt@goodmis.org>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 1/2] [RFC v2] seqcount: Add lockdep functionality to seqcount/seqlock structures
Date: Sat, 14 Sep 2013 16:42:56 +0800 [thread overview]
Message-ID: <52342190.1000409@huawei.com> (raw)
In-Reply-To: <1379117948-7385-1-git-send-email-john.stultz@linaro.org>
On 2013/9/14 8:19, John Stultz wrote:
> Currently seqlocks and seqcounts don't support lockdep.
>
> After running across a seqcount related deadlock in the timekeeping
> code, I used a less-refined and more focused varient of this patch
> to narrow down the cause of the issue.
>
> This is a first-pass attempt to properly enable lockdep functionality
> on seqlocks and seqcounts.
>
> Since seqcounts are used in the vdso gettimeofday code, I've provided
> lockdep accessors.
>
> I've also handled one cases where there were nested seqlock writers
> and there may be more edge cases.
>
> Comments and feedback would be appreciated!
>
Could you describe how seqlocks/seqcounts can lead to deadlock in the
changelog?
> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
> Cc: Li Zefan <lizefan@huawei.com>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Ingo Molnar <mingo@kernel.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Signed-off-by: John Stultz <john.stultz@linaro.org>
> ---
> v2:
> * Update to new simplified lockdep.h
> * vdso accessor simplifications
> * removed needless preempt_disable
> * removed unneeded ifdefs
next prev parent reply other threads:[~2013-09-14 8:45 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-14 0:19 [PATCH 1/2] [RFC v2] seqcount: Add lockdep functionality to seqcount/seqlock structures John Stultz
2013-09-14 0:19 ` [PATCH 2/2] [RFC] cpuset: Fix potential deadlock w/ set_mems_allowed John Stultz
2013-09-14 9:04 ` Li Zefan
2013-09-14 8:42 ` Li Zefan [this message]
2013-09-17 0:23 ` [PATCH 1/2] [RFC v2] seqcount: Add lockdep functionality to seqcount/seqlock structures John Stultz
2013-09-17 8:28 ` Ingo Molnar
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