From: Srivatsa Vaddagiri <vatsa@in.ibm.com>
To: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Andrew Morton <akpm@osdl.org>, Ingo Molnar <mingo@elte.hu>,
David Howells <dhowells@redhat.com>,
Christoph Hellwig <hch@infradead.org>,
Gautham R Shenoy <ego@in.ibm.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] reimplement flush_workqueue()
Date: Tue, 9 Jan 2007 10:31:04 +0530 [thread overview]
Message-ID: <20070109050104.GA29119@in.ibm.com> (raw)
In-Reply-To: <20061229171827.GA158@tv-sign.ru>
On Fri, Dec 29, 2006 at 08:18:27PM +0300, Oleg Nesterov wrote:
> Remove ->remove_sequence, ->insert_sequence, and ->work_done from struct
> cpu_workqueue_struct. To implement flush_workqueue() we can queue a barrier
> work on each CPU and wait for its completition.
Oleg,
Because of this change, was curious to know if this is possible:
CPU0 CPU1
(Thread0)
flush_workqueue()
queue_work(W1)
flush_cpu_workqueue(cpu1)
insert_barrier(B1)
wait_on_completion();
run_workqueue()
W1.func();
flush_workqueue();
B1.func(); <- wakes Thread0
The intention of barrier B1 was to wait untill W1 was -complete-. If
W1.func()->....->something() were to call flush_workqueue on the same
workqueue, then we would be returning from the barrier prematurely.
Looks possible in theory. Don't know if it is a practical issue.
--
Regards,
vatsa
next prev parent reply other threads:[~2007-01-09 5:01 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-12-29 17:18 [PATCH 1/2] reimplement flush_workqueue() Oleg Nesterov
2007-01-09 5:01 ` Srivatsa Vaddagiri [this message]
2007-01-09 15:55 ` Oleg Nesterov
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