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Subject: Re: [PATCH 2/2] posix-cpu-timers: use ->sighand instead of
 ->signal to check the task is alive
From: Peter Zijlstra <peterz@infradead.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, Ingo Molnar <mingo@elte.hu>,
       Lin Ming <ming.m.lin@intel.com>, Roland McGrath <roland@redhat.com>,
       "Zhang, Yanmin" <yanmin_zhang@linux.intel.com>,
       linux-kernel@vger.kernel.org
In-Reply-To: <20090203231717.GA5028@redhat.com>
References: <20090203231717.GA5028@redhat.com>
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Date: Wed, 04 Feb 2009 12:21:19 +0100
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On Wed, 2009-02-04 at 00:17 +0100, Oleg Nesterov wrote:
> Sadly, it is not trivial to audit kernel/posix-cpu-timers.c, but it really
> abuses tasklist_lock. I believe it doesn't need this lock at all, but the
> changes are not easy to test.

It uses that to hold of task reaping so ->signal doesn't go away.

If we make ->signal refcountable, and rcu freed along with the tasks I
think we can get away without tasklist_lock.