Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756724AbbESPQc (ORCPT ); Tue, 19 May 2015 11:16:32 -0400 Received: from mx1.redhat.com ([209.132.183.28]:34994 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752241AbbESPQa (ORCPT ); Tue, 19 May 2015 11:16:30 -0400 Date: Tue, 19 May 2015 17:16:28 +0200 From: Petr Holasek To: Arnaldo Carvalho de Melo Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Jiri Olsa Subject: Re: [PATCH] perf tools: rework of handling lack of sched_getcpu in old glibc Message-ID: <20150519151628.GC2387@stainedmachine> References: <1432041647-19981-1-git-send-email-pholasek@redhat.com> <20150519134951.GE13946@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150519134951.GE13946@kernel.org> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2857 Lines: 90 On Tue, 19 May 2015, Arnaldo Carvalho de Melo wrote: > Em Tue, May 19, 2015 at 03:20:47PM +0200, Petr Holasek escreveu: > > Commit e1e455f4f4d3 ("perf tools: Work around lack of sched_getcpu in > > glibc < 2.6.") introduced weak function sched_getcpu() which should > > be overridden by sched_getcpu() provided by glibc >= 2.6. Unfortunately, > > the weak function was linked to sched_getcpu() used in perf bench numa > > and made the benchmark heavily relying on this function unusable. > > > > This patch alternates weak function magic for preprocessor defines. > > With this you break the build again on RHEL5, right? That "fix" was a > quickie, the good thing would be to have this sched_getcpu() thing > somewhere else, far from its user, i.e. cloexec has no business doing > this if there are other places (perf bench numa) that need this, right? > > - Arnaldo > This fix is also quickie, since perf bench numa was unusable from 4.0-rc1 and I needed to fix it somehow. But I agree, the right place for the fix should be *far* from its users. > > > Signed-off-by: Petr Holasek > > --- > > tools/perf/util/cloexec.c | 13 +++++++++++-- > > tools/perf/util/cloexec.h | 6 ------ > > 2 files changed, 11 insertions(+), 8 deletions(-) > > > > diff --git a/tools/perf/util/cloexec.c b/tools/perf/util/cloexec.c > > index 85b5238..23b8aa9 100644 > > --- a/tools/perf/util/cloexec.c > > +++ b/tools/perf/util/cloexec.c > > @@ -7,11 +7,20 @@ > > > > static unsigned long flag = PERF_FLAG_FD_CLOEXEC; > > > > -int __weak sched_getcpu(void) > > +#ifdef __GLIBC_PREREQ > > +#if !__GLIBC_PREREQ(2, 6) > > +static int do_sched_getcpu(void) > > { > > errno = ENOSYS; > > return -1; > > } > > +#else > > +static int do_sched_getcpu(void) > > +{ > > + return sched_getcpu(); > > +} > > +#endif > > +#endif > > > > static int perf_flag_probe(void) > > { > > @@ -27,7 +36,7 @@ static int perf_flag_probe(void) > > pid_t pid = -1; > > char sbuf[STRERR_BUFSIZE]; > > > > - cpu = sched_getcpu(); > > + cpu = do_sched_getcpu(); > > if (cpu < 0) > > cpu = 0; > > > > diff --git a/tools/perf/util/cloexec.h b/tools/perf/util/cloexec.h > > index 68888c2..94a5a7d 100644 > > --- a/tools/perf/util/cloexec.h > > +++ b/tools/perf/util/cloexec.h > > @@ -3,10 +3,4 @@ > > > > unsigned long perf_event_open_cloexec_flag(void); > > > > -#ifdef __GLIBC_PREREQ > > -#if !__GLIBC_PREREQ(2, 6) > > -extern int sched_getcpu(void) __THROW; > > -#endif > > -#endif > > - > > #endif /* __PERF_CLOEXEC_H */ > > -- > > 2.1.0 -- Petr Holasek pholasek@redhat.com -- 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/