From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753141AbaJ0XLP (ORCPT ); Mon, 27 Oct 2014 19:11:15 -0400 Received: from mx1.redhat.com ([209.132.183.28]:58168 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753110AbaJ0XLM (ORCPT ); Mon, 27 Oct 2014 19:11:12 -0400 Date: Tue, 28 Oct 2014 01:07:03 +0100 From: Oleg Nesterov To: Peter Zijlstra Cc: Mike Galbraith , mingo@kernel.org, torvalds@linux-foundation.org, tglx@linutronix.de, ilya.dryomov@inktank.com, linux-kernel@vger.kernel.org, Eric Paris , rafael.j.wysocki@intel.com Subject: Re: [PATCH 00/11] nested sleeps, fixes and debug infrastructure Message-ID: <20141028000703.GA22964@redhat.com> References: <20140924081845.572814794@infradead.org> <1411633803.15810.12.camel@marge.simpson.net> <20140925090619.GA5430@worktop> <20140925091556.GB5430@worktop> <20141002102251.GA6324@worktop.programming.kicks-ass.net> <20141002121553.GB6324@worktop.programming.kicks-ass.net> <20141027134103.GA10476@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20141027134103.GA10476@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/27, Peter Zijlstra wrote: > > On Thu, Oct 02, 2014 at 02:15:53PM +0200, Peter Zijlstra wrote: > > On Thu, Oct 02, 2014 at 12:22:51PM +0200, Peter Zijlstra wrote: > > > > +#define __wait_event_freezable(wq, condition) \ > > > + (void)___wait_event(wq, condition, TASK_INTERRUPTIBLE, 0, 0, \ > > > + schedule(); try_to_freeze()) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ see below. > > > + > > > +/** > > > + * wait_event - sleep until a condition gets true or freeze (for kthreads) > > > + * @wq: the waitqueue to wait on > > > + * @condition: a C expression for the event to wait for > > > + * > > > + * The process is put to sleep (TASK_INTERRUPTIBLE -- so as not to contribute > > > + * to system load) until the @condition evaluates to true. The > > > + * @condition is checked each time the waitqueue @wq is woken up. > > > + * > > > + * wake_up() has to be called after changing any variable that could > > > + * change the result of the wait condition. > > > + */ > > > +#define wait_event_freezable(wq, condition) \ > > > +do { \ > > > + WARN_ON_ONCE(!(current->flags & PF_KTHREAD)); \ > > > + might_sleep(); \ > > > + if (condition) \ > > > + break; \ > > > + __wait_event_freezable(wq, condition); \ > > > +} while (0) > > > + > > > #define __wait_event_timeout(wq, condition, timeout) \ > > > ___wait_event(wq, ___wait_cond_timeout(condition), \ > > > TASK_UNINTERRUPTIBLE, 0, timeout, \ > > > > Bah, that doesn't compile, because there already appears to be one, > > hidden in freezer.h. Now I can't actually tell if it does the same thing > > or not. > > > > Rafael? > > Ping? I was going to say that wait_event_freezable() in kauditd_thread() is not friendly wrt kthread_should_stop() and thus we we need kthread_freezable_should_stop(). But in fact we never stop this kauditd_task, so I think we should turn the main loop into "for (;;)" and change this code to use wait_event_freezable() like your patch does. Perhaps it also makes sense to redefine wait_event_freezable.*() via ___wait_event(cmd => freezable_schedule), but I think this needs another patch. Oleg.