From: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>,
linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Ulrich Drepper <drepper@redhat.com>
Subject: Re: [RFC][PATCH] muptiple bugs in PI futexes
Date: Wed, 6 Jun 2007 01:00:28 +0400 [thread overview]
Message-ID: <20070605210028.GA10084@ms2.inr.ac.ru> (raw)
In-Reply-To: <1181070953.4404.149.camel@chaos>
Hello!
> We actually need to do something about this, as we might loop for ever
> there. The robust cleanup code can fail (e.g. due to list corruption)
> and we would see exit_state != 0 and the OWNER_DIED bit would never be
> set, so we are stuck in a busy loop.
Yes...
It is possible to take read_lock(&tasklist_lock) before:
inc_preempt_count();
curval = futex_atomic_cmpxchg_inatomic(uaddr, uval, newval);
dec_preempt_count();
and drop it after lookup_pi_state().
In this case exiting task will set FUTEX_OWNER_DIED, but will
spin in exit_notify(), we will find valid pi_state and go slow path
taking rtmutex.
Alexey
next prev parent reply other threads:[~2007-06-05 21:01 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-05-07 14:43 Alexey Kuznetsov
2007-05-23 7:26 ` Ingo Molnar
2007-05-23 11:51 ` Alexey Kuznetsov
2007-06-05 16:25 ` Thomas Gleixner
2007-06-05 17:39 ` Alexey Kuznetsov
2007-06-05 18:48 ` Thomas Gleixner
2007-06-05 19:15 ` Thomas Gleixner
2007-06-05 21:00 ` Alexey Kuznetsov [this message]
2007-06-05 21:13 ` Thomas Gleixner
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