Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754192Ab3HAL17 (ORCPT ); Thu, 1 Aug 2013 07:27:59 -0400 Received: from mx1.redhat.com ([209.132.183.28]:2034 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753193Ab3HAL16 (ORCPT ); Thu, 1 Aug 2013 07:27:58 -0400 Date: Thu, 1 Aug 2013 13:30:50 +0200 From: Stanislaw Gruszka To: Dong Zhu Cc: John Stultz , Thomas Gleixner , Oleg Nesterov , Ingo Molnar , linux-kernel@vger.kernel.org Subject: Re: [PATCH] posix_cpu_timers: fix timer never expires when executes clock_nanosleep Message-ID: <20130801113049.GB7334@redhat.com> References: <20130801101018.GJ6721@zhudong.nay.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130801101018.GJ6721@zhudong.nay.redhat.com> 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 Content-Length: 1376 Lines: 35 Hi Dong Zhu On Thu, Aug 01, 2013 at 06:10:19PM +0800, Dong Zhu wrote: > diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c > index c7f31aa..cc03290 100644 > --- a/kernel/posix-cpu-timers.c > +++ b/kernel/posix-cpu-timers.c > @@ -1413,9 +1413,9 @@ static int posix_cpu_nsleep(const clockid_t which_clock, int flags, > /* > * Diagnose required errors first. > */ > - if (CPUCLOCK_PERTHREAD(which_clock) && > - (CPUCLOCK_PID(which_clock) == 0 || > - CPUCLOCK_PID(which_clock) == current->pid)) > + if (CPUCLOCK_PID(which_clock) == current->pid || > + (CPUCLOCK_PERTHREAD(which_clock) && > + CPUCLOCK_PID(which_clock) == 0)) > return -EINVAL; Nope, this is wrong. We have to allow own pid process clock, because it can be used correctly on multi-threaded processes. Own tid thread clock has no sense and we correctly return -EINVAL in such case. We could possibly add check for own pid together with check if process consist of one thread, but that is too complicated IMHO especially taking into account that threads on the process can be destroyed and created dynamically. Stanislaw -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/