From: Oleg Nesterov <oleg@tv-sign.ru>
To: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Ingo Molnar <mingo@elte.hu>,
Andrew Morton <akpm@linux-foundation.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Alexey Dobriyan <adobriyan@gmail.com>
Subject: Re: [PATCH] signal, procfs: lock_task_sighand() do not need rcu_read_lock()
Date: Fri, 3 Oct 2008 20:29:15 +0400 [thread overview]
Message-ID: <20081003162915.GA624@tv-sign.ru> (raw)
In-Reply-To: <48E5ED4D.4030102@cn.fujitsu.com>
On 10/03, Lai Jiangshan wrote:
>
> lock_task_sighand() make sure task->sighand is being protected,
> so we do not need rcu_read_lock().
> [ exec() will get task->sighand->siglock before change task->sighand! ]
>
> But code using rcu_read_lock() _just_ to protect lock_task_sighand()
> only appear in procfs. (and some code in procfs use lock_task_sighand()
> without such redundant protection.)
Yes, the patch looks correct.
The initial implementaion of lock_task_sighand() did not take RCU lock,
that is why we still have the callers which call rcu_read_lock().
See 1406f2d321bae5ac5ff729dcb773336d9c05ec74.
Thanks!
Oleg.
next prev parent reply other threads:[~2008-10-03 16:23 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-10-03 10:00 Lai Jiangshan
2008-10-03 16:29 ` Oleg Nesterov [this message]
2008-10-04 20:55 ` Alexey Dobriyan
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