From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755792AbaGNO1d (ORCPT ); Mon, 14 Jul 2014 10:27:33 -0400 Received: from mail-qg0-f47.google.com ([209.85.192.47]:41146 "EHLO mail-qg0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755299AbaGNO1K (ORCPT ); Mon, 14 Jul 2014 10:27:10 -0400 Date: Mon, 14 Jul 2014 10:27:07 -0400 From: Tejun Heo To: Lai Jiangshan Cc: linux-kernel@vger.kernel.org, Thomas Gleixner Subject: Re: [PATCH 1/1 V2] workqueue: remove the del_timer_sync()s in maybe_create_worker() Message-ID: <20140714142707.GB31610@htj.dyndns.org> References: <1405265479-827-1-git-send-email-laijs@cn.fujitsu.com> <1405325601-12437-1-git-send-email-laijs@cn.fujitsu.com> <1405325601-12437-2-git-send-email-laijs@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1405325601-12437-2-git-send-email-laijs@cn.fujitsu.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Mon, Jul 14, 2014 at 04:13:21PM +0800, Lai Jiangshan wrote: > It is said in the document that the timer which is being > deleted by del_timer_sync() should not be restarted: > Synchronization rules: Callers must prevent restarting of > the timer, otherwise this function is meaningless. > > Repeating timer may cause the del_timer_sync() spin longer, > or even spin forever in very very very very extreme condition. I'm fairly sure del_timer_sync() can delete self-requeueing timers. The implementation busy-waits if the queued timer is the currently executing one and dequeues only while the timer isn't running which should be able to handle self-requeueing ones just fine. Thomas, del_timer_sync() can reliably delete self-requeueing ones, right? Thanks. -- tejun