From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751983AbcFNMlQ (ORCPT ); Tue, 14 Jun 2016 08:41:16 -0400 Received: from foss.arm.com ([217.140.101.70]:58459 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751029AbcFNMlP (ORCPT ); Tue, 14 Jun 2016 08:41:15 -0400 Date: Tue, 14 Jun 2016 13:41:14 +0100 From: Juri Lelli To: Peter Zijlstra Cc: mingo@kernel.org, tglx@linutronix.de, rostedt@goodmis.org, xlpang@redhat.com, linux-kernel@vger.kernel.org, mathieu.desnoyers@efficios.com, jdesfossez@efficios.com, bristot@redhat.com Subject: Re: [RFC][PATCH 5/8] rtmutex: Clean up Message-ID: <20160614124114.GI5981@e106622-lin> References: <20160607195635.710022345@infradead.org> <20160607200215.923213194@infradead.org> <20160614120813.GH5981@e106622-lin> <20160614123253.GH30921@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160614123253.GH30921@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 14/06/16 14:32, Peter Zijlstra wrote: > On Tue, Jun 14, 2016 at 01:08:13PM +0100, Juri Lelli wrote: > > > + postunlock = rt_mutex_futex_unlock(&pi_state->pi_mutex, &wake_q); > > > > > > /* > > > * First unlock HB so the waiter does not spin on it once he got woken > > > + * up. Then wakeup the waiter by calling rt_mutex_postunlock(). Priority > > > + * is already adjusted and preemption is disabled to avoid inversion. > > > */ > > > spin_unlock(&hb->lock); > > > > > > + if (postunlock) > > > + rt_mutex_postunlock(&wake_q); > > > > I'm most probably missing something, but don't we still need to call > > wake_up_q() even when postunlock is false? IIUC, we were always doing > > that, rt_mutex_postunlock(), before this change (only calling > > preempt_enable() was conditional). > > Note that rt_mutex_slowunlock() only uses wake_q on the true path. When > it returns false, it will not have placed a task to wake up. > Right. But, I thought we were still ending up calling wake_up_q before this change. Which however looked fine, as it won't do anything if no task is queued I guess. So, no problem before and no problem now I'd say. :-)