From: Oleg Nesterov <oleg@tv-sign.ru>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
Eric Dumazet <dada1@cosmosbay.com>, Ingo Molnar <mingo@elte.hu>,
Steven Rostedt <rostedt@goodmis.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ulrich Drepper <drepper@redhat.com>,
linux-kernel@vger.kernel.org
Subject: [PATCH] pi-futex: set PF_EXITING without taking ->pi_lock
Date: Sat, 21 Jul 2007 15:57:12 +0400 [thread overview]
Message-ID: <20070721115712.GA871@tv-sign.ru> (raw)
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>
--- t/kernel/exit.c~PF_EXIT 2007-06-19 17:09:15.000000000 +0400
+++ t/kernel/exit.c 2007-07-21 15:34:13.000000000 +0400
@@ -908,13 +908,13 @@ fastcall NORET_TYPE void do_exit(long co
schedule();
}
+ tsk->flags |= PF_EXITING;
/*
* tsk->flags are checked in the futex code to protect against
* an exiting task cleaning up the robust pi futexes.
*/
- spin_lock_irq(&tsk->pi_lock);
- tsk->flags |= PF_EXITING;
- spin_unlock_irq(&tsk->pi_lock);
+ smp_mb();
+ spin_unlock_wait(&tsk->pi_lock);
if (unlikely(in_atomic()))
printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
next reply other threads:[~2007-07-21 11:57 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-07-21 11:57 Oleg Nesterov [this message]
2007-07-21 12:31 ` [PATCH] pi-futex: set PF_EXITING without taking ->pi_lock Ingo Molnar
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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