Date: Sun, 7 Jan 2007 17:42:36 +0300
From: Oleg Nesterov <oleg@tv-sign.ru>
To: Srivatsa Vaddagiri <vatsa@in.ibm.com>
Cc: Andrew Morton <akpm@osdl.org>, David Howells <dhowells@redhat.com>,
       Christoph Hellwig <hch@infradead.org>, Ingo Molnar <mingo@elte.hu>,
       Linus Torvalds <torvalds@osdl.org>, linux-kernel@vger.kernel.org,
       Gautham shenoy <ego@in.ibm.com>
Subject: Re: [PATCH] fix-flush_workqueue-vs-cpu_dead-race-update
Message-ID: <20070107144236.GB149@tv-sign.ru>
References: <20070104142936.GA179@tv-sign.ru> <20070104091850.c1feee76.akpm@osdl.org> <20070106151036.GA951@tv-sign.ru> <20070106154506.GC24274@in.ibm.com> <20070106163035.GA2948@tv-sign.ru> <20070106163851.GA13579@in.ibm.com> <20070106173416.GA3771@tv-sign.ru> <20070107104328.GC13579@in.ibm.com> <20070107125603.GA74@tv-sign.ru> <20070107142246.GA149@tv-sign.ru>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20070107142246.GA149@tv-sign.ru>
User-Agent: Mutt/1.5.11
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 831
Lines: 27

On 01/07, Oleg Nesterov wrote:
> 
> How about:
> 
> 	CPU_DEAD does nothing. After __cpu_disable() cwq->thread runs on
> 	all CPUs and becomes idle when it flushes cwq->worklist: nobody
> 	will add work_struct on that list.

Also, we can add cpu_workqueue_struct->should_exit_after_flush flag, but
we have to be careful to serialize with destroy_workqueue/CPU_UP.

> 	CPU_UP:
> 		if (!cwq->thread)
> 			create_workqueue_thread();
> 		else
> 			set_cpus_allowed(newcpu);
> 
> 	flush_workqueue:
> 		for_each_possible_cpu()		// NOT online!
> 			if (cwq->thread)
> 				flush_cpu_workqueue()

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/