From: Ingo Molnar <mingo@elte.hu>
To: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
Eric Dumazet <dada1@cosmosbay.com>,
Steven Rostedt <rostedt@goodmis.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ulrich Drepper <drepper@redhat.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] pi-futex: set PF_EXITING without taking ->pi_lock
Date: Sat, 21 Jul 2007 14:31:59 +0200 [thread overview]
Message-ID: <20070721123159.GB1769@elte.hu> (raw)
In-Reply-To: <20070721115712.GA871@tv-sign.ru>
* Oleg Nesterov <oleg@tv-sign.ru> wrote:
> It is a bit annoying that do_exit() takes ->pi_lock to set PF_EXITING.
> All we need is to synchronize with lookup_pi_state() which saw this task
> without PF_EXITING under ->pi_lock.
>
> Change do_exit() to use spin_unlock_wait().
>
> Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Ingo Molnar <mingo@elte.hu>
> - spin_lock_irq(&tsk->pi_lock);
> - tsk->flags |= PF_EXITING;
> - spin_unlock_irq(&tsk->pi_lock);
> + smp_mb();
> + spin_unlock_wait(&tsk->pi_lock);
hm, isnt spin_unlock_wait() an SMP barrier in itself? (if not then it
should be.)
Ingo
next prev parent reply other threads:[~2007-07-21 12:33 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-07-21 11:57 [PATCH] pi-futex: set PF_EXITING without taking ->pi_lock Oleg Nesterov
2007-07-21 12:31 ` Ingo Molnar [this message]
2007-07-21 14:18 ` Oleg Nesterov
2007-07-21 15:02 ` [PATCH] fix theoretical ccids_{read,write}_lock() race Oleg Nesterov
2007-07-21 19:02 ` Andrew Morton
2007-07-21 19:11 ` Oleg Nesterov
2007-07-21 19:21 ` Andrew Morton
2007-07-21 20:06 ` Oleg Nesterov
2007-07-21 15:05 ` [PATCH] pi-futex: set PF_EXITING without taking ->pi_lock Ingo Molnar
2007-07-21 16:39 ` Oleg Nesterov
2007-08-06 7:30 ` Ingo Molnar
2007-07-22 0:31 ` Paul Mackerras
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