Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932356AbZKSDV7 (ORCPT ); Wed, 18 Nov 2009 22:21:59 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757988AbZKSDV4 (ORCPT ); Wed, 18 Nov 2009 22:21:56 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:59243 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757980AbZKSDVz (ORCPT ); Wed, 18 Nov 2009 22:21:55 -0500 Date: Thu, 19 Nov 2009 04:20:24 +0100 From: Ingo Molnar To: Sven-Thorsten Dietrich , Peter Zijlstra Cc: Jean Delvare , Leon Woestenberg , Alan Cox , Mark Brown , Thomas Gleixner , linux-i2c@vger.kernel.org, rt-users , "Ben Dooks (embedded platforms)" , Peter Zijlstra , LKML Subject: Re: [PATCH] cleanup sched_yield (sys)call nesting. Message-ID: <20091119032024.GA13378@elte.hu> References: <20091107210147.3e754278@hyperion.delvare> <4AF7148C.9090706@thebigcorporation.com> <20091112211255.09cd884a@hyperion.delvare> <20091116155606.GC29479@sirena.org.uk> <20091118010520.4cd397d4@lxorguk.ukuu.org.uk> <20091118175202.490989d8@hyperion.delvare> <1258577194.12429.86.camel@sven.thebigcorporation.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1258577194.12429.86.camel@sven.thebigcorporation.com> User-Agent: Mutt/1.5.20 (2009-08-17) X-ELTE-SpamScore: 0.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=0.0 required=5.9 tests=none autolearn=no SpamAssassin version=3.2.5 _SUMMARY_ Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1883 Lines: 65 * Sven-Thorsten Dietrich wrote: > Subject: clean up chaining in sched_yield() > From: Sven-Thorsten Dietrich > > The call to sys_sched_yield for in-Kernel is messy. > and the return code from sys_sched_yield is ignored when called from > in-kernel. > > Signed-off-by: Sven-Thorsten Dietrich > > diff --git a/kernel/sched.c b/kernel/sched.c > index 3c11ae0..db2c0f9 100644 > --- a/kernel/sched.c > +++ b/kernel/sched.c > @@ -6647,12 +6647,12 @@ SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len, > } > > /** > - * sys_sched_yield - yield the current processor to other threads. > + * do_sched_yield - yield the current processor to other threads. > * > * This function yields the current CPU to other tasks. If there are no > * other threads running on this CPU then this function will return. > */ > -SYSCALL_DEFINE0(sched_yield) > +static inline void do_sched_yield(void) > { > struct rq *rq = this_rq_lock(); > > @@ -6669,6 +6669,11 @@ SYSCALL_DEFINE0(sched_yield) > preempt_enable_no_resched(); > > schedule(); > +} > + > +SYSCALL_DEFINE0(sched_yield) > +{ > + do_sched_yield(); > > return 0; > } > @@ -6746,7 +6751,7 @@ EXPORT_SYMBOL(__cond_resched_softirq); > void __sched yield(void) > { > set_current_state(TASK_RUNNING); > - sys_sched_yield(); > + do_sched_yield(); > } > EXPORT_SYMBOL(yield); Why do you consider an in-kernel call to sys_*() 'messy'? It is not - and we rely on being able to do it with various syscalls. Also, your patch bloats the scheduler a bit, for no good reason. Thanks, Ingo -- 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/