From: David Howells <dhowells@redhat.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: dhowells@redhat.com, Andrew Morton <akpm@linux-foundation.org>,
David Miller <davem@davemloft.net>,
Serge Hallyn <serue@us.ibm.com>,
Steve Dickson <steved@redhat.com>,
Trond Myklebust <Trond.Myklebust@netapp.com>,
Al Viro <viro@zeniv.linux.org.uk>,
Daire Byrne <Daire.Byrne@framestore.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] slow_work_execute() needs mb() before test_bit(SLOW_WORK_PENDING)
Date: Thu, 16 Apr 2009 10:43:42 +0100 [thread overview]
Message-ID: <14774.1239875022@redhat.com> (raw)
In-Reply-To: <20090413220201.GA1368@redhat.com>
Oleg Nesterov <oleg@redhat.com> wrote:
> But why do we need the barrier before clear_bit(SLOW_WORK_EXECUTING) ?
> We do have one after test_and_clear_bit(SLOW_WORK_PENDING) above, and it
> should be enough, no?
No. There lock is covering work->ops->execute(work) too, and that is after
the clearance of SLOW_WORK_PENDING. The UNLOCK-class barrier must go between
execution and clearance of the execution lock bit.
David
next prev parent reply other threads:[~2009-04-16 9:45 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-04-13 20:13 [PATCH] slow_work_execute() needs mb() before test_bit(SLOW_WORK_PENDING) Oleg Nesterov
2009-04-13 20:13 ` Oleg Nesterov
2009-04-13 21:47 ` David Howells
2009-04-13 22:02 ` Oleg Nesterov
2009-04-16 9:43 ` David Howells [this message]
2009-04-16 14:15 ` Oleg Nesterov
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