From: Michal Hocko <mhocko@kernel.org>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
David Howells <dhowells@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: wake_up_process implied memory barrier clarification
Date: Thu, 27 Aug 2015 14:27:27 +0200 [thread overview]
Message-ID: <20150827122727.GC27052@dhcp22.suse.cz> (raw)
Hi,
I have just stumbled over the comment above wake_up_process which
claims:
"
* It may be assumed that this function implies a write memory barrier before
* changing the task state if and only if any tasks are woken up.
"
but try_to_wake_up does smp_mb__before_spinlock and did smp_wmb
since 04e2f1741d235 unconditionally. The comment was added when the
smp_wmb was in place already so I am wondering whether the comment is
wrong/misleading.
Could somebody clarify please?
--
Michal Hocko
SUSE Labs
next reply other threads:[~2015-08-27 12:27 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-27 12:27 Michal Hocko [this message]
2015-08-27 12:43 ` Peter Zijlstra
2015-08-27 13:14 ` Michal Hocko
2015-08-27 18:26 ` Oleg Nesterov
2015-08-28 14:51 ` Michal Hocko
2015-08-28 16:06 ` Oleg Nesterov
2015-08-29 9:25 ` Boqun Feng
2015-08-29 14:27 ` Oleg Nesterov
2015-08-31 0:37 ` Boqun Feng
2015-08-31 18:33 ` Oleg Nesterov
2015-08-31 20:37 ` Paul E. McKenney
2015-09-01 3:40 ` Boqun Feng
2015-09-01 4:03 ` Paul E. McKenney
2015-09-01 9:59 ` Oleg Nesterov
2015-09-01 14:50 ` Boqun Feng
2015-09-01 16:39 ` Oleg Nesterov
2015-09-02 1:10 ` Boqun Feng
2015-09-07 17:06 ` Oleg Nesterov
2015-09-08 0:22 ` Boqun Feng
2015-09-01 9:41 ` Oleg Nesterov
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