From: Ingo Molnar <mingo@elte.hu>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: David Howells <dhowells@redhat.com>,
Oleg Nesterov <oleg@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
serue@us.ibm.com, viro@zeniv.linux.org.uk,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Nick Piggin <nickpiggin@yahoo.com.au>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] It may not be assumed that wake_up(), finish_wait() and co. imply a memory barrier
Date: Thu, 23 Apr 2009 23:24:34 +0200 [thread overview]
Message-ID: <20090423212434.GA20556@elte.hu> (raw)
In-Reply-To: <alpine.LFD.2.00.0904231410590.3101@localhost.localdomain>
* Linus Torvalds <torvalds@linux-foundation.org> wrote:
> On Thu, 23 Apr 2009, David Howells wrote:
> >
> > Well, Ingo's point is it could be left up to the caller of
> > wake_up() to supply the barrier:
Well, i mainly reacted to your documentation patch which was
incorrect as it said wake-up implies a _FULL_ memory barrier.
I also suggested that lockless code should have its barriers clearly
documented and they should not really rely on kernel facilities
acting as memory barriers.
Then i also suggested that maybe in the future we could remove the
smp_wmb() from try_to_wake_up(). That was just an afterthought, and
a rather stupid one at that, as Linus quickly noted :-)
Ingo
next prev parent reply other threads:[~2009-04-23 21:25 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-04-13 18:17 [PATCH] slow_work_thread() should do the exclusive wait Oleg Nesterov
2009-04-13 19:03 ` Trond Myklebust
2009-04-13 19:14 ` Oleg Nesterov
2009-04-13 21:40 ` David Howells
2009-04-13 21:48 ` Oleg Nesterov
2009-04-13 21:57 ` Trond Myklebust
2009-04-13 22:24 ` Oleg Nesterov
2009-04-15 23:27 ` Andrew Morton
2009-04-16 9:10 ` David Howells
2009-04-16 14:33 ` Oleg Nesterov
2009-04-22 13:37 ` [PATCH] Document that wake_up(), complete() and co. imply a full memory barrier David Howells
2009-04-22 13:51 ` Ingo Molnar
2009-04-22 14:39 ` Oleg Nesterov
2009-04-22 14:56 ` Ingo Molnar
2009-04-22 15:07 ` Oleg Nesterov
2009-04-22 15:12 ` David Howells
2009-04-22 15:19 ` Ingo Molnar
2009-04-22 16:23 ` David Howells
2009-04-22 17:57 ` Ingo Molnar
2009-04-23 16:32 ` [PATCH] It may not be assumed that wake_up(), finish_wait() and co. imply a " David Howells
2009-04-23 16:55 ` Oleg Nesterov
2009-04-24 11:46 ` David Howells
2009-04-24 15:08 ` Paul E. McKenney
2009-04-24 17:08 ` Oleg Nesterov
2009-04-24 17:43 ` Paul E. McKenney
2009-04-24 17:48 ` David Howells
2009-04-24 18:06 ` Paul E. McKenney
2009-04-28 10:18 ` David Howells
2009-04-28 13:00 ` Paul E. McKenney
2009-04-24 17:28 ` Oleg Nesterov
2009-04-24 17:53 ` David Howells
2009-04-24 18:30 ` Oleg Nesterov
2009-04-23 17:07 ` Linus Torvalds
2009-04-23 20:35 ` David Howells
2009-04-23 21:12 ` Linus Torvalds
2009-04-23 21:24 ` Ingo Molnar [this message]
2009-04-23 16:36 ` [PATCH] Document that wake_up(), complete() and co. imply a full " Oleg Nesterov
2009-04-23 20:37 ` David Howells
2009-04-23 16:00 ` [PATCH] slow_work_thread() should do the exclusive wait David Howells
2009-04-23 16:18 ` Oleg Nesterov
2009-04-13 21:35 ` David Howells
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