From: David Howells <dhowells@redhat.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: dhowells@redhat.com, Andrew Morton <akpm@linux-foundation.org>,
Dmitry Torokhov <dmitry.torokhov@gmail.com>,
Jiri Pirko <jpirko@redhat.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Peter Zijlstra <peterz@infradead.org>,
linux-kernel@vger.kernel.org
Subject: Re: [RFC,PATCH] workqueues: turn queue_work() into the "barrier" for work->func()
Date: Tue, 11 Nov 2008 22:46:21 +0000 [thread overview]
Message-ID: <9266.1226443581@redhat.com> (raw)
In-Reply-To: <20081111203324.GA30425@redhat.com>
Oleg Nesterov <oleg@redhat.com> wrote:
> I think the caller of queue_work() has all rights to expect that
> the next invocation of work_func() must see "VAR == 1", but this
> is not true if the work is already pending.
As you said, queue_work() does test_and_set_bit() which implies smp_mb()
either side of the function, so you're half way there, and run_workqueue()
calls spin_unlock_irq() just before calling work_clear_pending()... So might
it make sense to move the work_clear_pending() into locked section? Or would
that require an smp_mb__before_clear_bit()?
David
next prev parent reply other threads:[~2008-11-11 22:47 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-11-11 20:33 [RFC,PATCH] workqueues: turn queue_work() into the "barrier" for work->func() Oleg Nesterov
2008-11-11 22:46 ` David Howells [this message]
2008-11-12 11:58 ` Oleg Nesterov
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