From: Oleg Nesterov <oleg@redhat.com>
To: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH for-3.3] mempool: clean up and document synchronization and memory barrier usage
Date: Wed, 21 Dec 2011 15:57:14 +0100 [thread overview]
Message-ID: <20111221145714.GB25657@redhat.com> (raw)
In-Reply-To: <20111221145556.GA25657@redhat.com>
On 12/21, Oleg Nesterov wrote:
>
> On 12/20, Tejun Heo wrote:
> >
> > Furthermore, mempool_alloc() is already holding pool->lock when it
> > decides that it needs to wait. There is no reason to do unlock - add
> > waitqueue - test condition again. It can simply add itself to
> > waitqueue while holding pool->lock and then unlock and sleep.
>
> Confused. I agree, we can hold pool->lock until schedule(). But, at
> the same time, why should we hold it?
Ah, I see.
> Or I missed the reason why we must not unlock before prepare_to_wait?
I didn't notice that this removes another "if (!pool->curr_nr)" check.
Oleg.
next prev parent reply other threads:[~2011-12-21 15:02 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-20 22:18 [PATCH for-3.3] mempool: clean up and document synchronization and memory barrier usage Tejun Heo
2011-12-21 14:55 ` Oleg Nesterov
2011-12-21 14:57 ` Oleg Nesterov [this message]
2011-12-21 16:37 ` Tejun Heo
2011-12-21 16:44 ` Tejun Heo
2011-12-21 17:40 ` Oleg Nesterov
2011-12-21 18:52 ` Tejun Heo
2011-12-21 15:12 ` mempool && io_schedule_timeout() Oleg Nesterov
2011-12-21 15:34 ` Tejun Heo
2011-12-21 19:08 ` [PATCH for-3.3 UPDATED] mempool: fix and document synchronization and memory barrier usage Tejun Heo
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