From mboxrd@z Thu Jan 1 00:00:00 1970 From: Florian Mickler Subject: Re: [PATCH v4] pm_qos: make update_request non blocking Date: Wed, 9 Jun 2010 18:00:33 +0200 Message-ID: <20100609180033.39d5b499__28304.0639864796$1276099302$gmane$org@schatten.dmk.lab> References: <1276097381-3982-1-git-send-email-florian@mickler.org> <1276097832.4343.223.camel@mulgrave.site> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1276097832.4343.223.camel@mulgrave.site> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-pm-bounces@lists.linux-foundation.org Errors-To: linux-pm-bounces@lists.linux-foundation.org To: James Bottomley Cc: Jonathan Corbet , Frederic Weisbecker , markgross@thegnar.org, linville@tuxdriver.com, linux-kernel@vger.kernel.org, pm list , Thomas Gleixner List-Id: linux-pm@vger.kernel.org On Wed, 09 Jun 2010 11:37:12 -0400 James Bottomley wrote: > This still isn't resilient against two successive calls to update. If > the second one gets to schedule_work() before the work of the first one > has finished, you'll corrupt the workqueue. Sorry, I don't see it. Can you elaborate? In "run_workqueue(" we do a list_del_init() which resets the list-pointers of the workitem and only after that reset the WORK_STRUCT_PENDING member of said structure. schedule_work does a queue_work_on which does a test_and_set_bit on the WORK_STRUCT_PENDING member of the work and only queues the work via list_add_tail in insert_work afterwards. Where is my think'o? Or was this fixed while you didn't look? So what _can_ happen, is that we miss a new notfication while the old notification is still in the queue. But I don't think this is a problem. Cheers, Flo