From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933445AbbEEQoG (ORCPT ); Tue, 5 May 2015 12:44:06 -0400 Received: from smtprelay0247.hostedemail.com ([216.40.44.247]:36209 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1761518AbbEEQmr (ORCPT ); Tue, 5 May 2015 12:42:47 -0400 X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Spam-Summary: 2,0,0,,d41d8cd98f00b204,rostedt@goodmis.org,:::::::::,RULES_HIT:41:355:379:541:599:800:960:988:989:1260:1277:1311:1313:1314:1345:1359:1437:1515:1516:1518:1534:1541:1593:1594:1711:1730:1747:1777:1792:2194:2199:2393:2553:2559:2562:2693:2910:3138:3139:3140:3141:3142:3352:3622:3865:3867:3870:3871:3872:3874:4250:4559:4605:5007:6261:7875:8660:10004:10400:10848:10967:11026:11232:11658:11914:12043:12198:12438:12517:12519:12740:13069:13148:13230:13311:13357:14096:14097:21080,0,RBL:none,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fn,MSBL:0,DNSBL:none,Custom_rules:0:0:0 X-HE-Tag: room15_180eca077752d X-Filterd-Recvd-Size: 2056 Date: Tue, 5 May 2015 12:42:44 -0400 From: Steven Rostedt To: Thomas Gleixner Cc: Mike Galbraith , Ronny Meeus , LKML , Peter Zijlstra Subject: Re: [PATCH] sched: Handle priority boosted tasks proper in setscheduler() Message-ID: <20150505124244.1f154dc9@gandalf.local.home> In-Reply-To: References: <20150505122920.7861907d@gandalf.local.home> X-Mailer: Claws Mail 3.11.1 (GTK+ 2.24.25; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 5 May 2015 18:31:20 +0200 (CEST) Thomas Gleixner wrote: > On Tue, 5 May 2015, Steven Rostedt wrote: > > I got pulled onto other things so I never finished it, but one thing > > that worried me about this fix is this: > > > > T1 - FIFO policy (prio = 10) > > lock(rtmutex); > > > > T2 (prio = 20) > > lock(rtmutex) > > boost T1 (prio = 20) > > > > TI (prio = 20) > > sys_sched_setscheduler(prio = 30) > > TI (prio = 30) > > > > T1 (prio = 30) > > sys_sched_setscheduler(SCHED_OTHER) > > new_effective_prio = 20, oldprio = 30 > > > > Before the code stopped at the rt_mutex_check_prio(), but now it > > continues. Will having the policy change cause problems here? > > No, because it stays effective in the FIFO domain. > Ah, the policy passed in isn't used, so we are safe. But, but I also found that we still call __setscheduler(), which does: p->prio = normal_prio(); Isn't that going to null out the boosting? -- Steve