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Date: Tue, 24 Mar 2015 08:10:53 +0100
From: Jiri Olsa <jolsa@redhat.com>
To: Vinson Lee <vlee@twopensource.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>, Paul Mackerras <paulus@samba.org>,
        Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
        Namhyung Kim <namhyung@kernel.org>,
        Yann Droneaud <ydroneaud@opteya.com>, linux-kernel@vger.kernel.org,
        linux-perf-users@vger.kernel.org, Vinson Lee <vlee@twitter.com>
Subject: Re: [PATCH v3] perf tools: Work around lack of sched_getcpu in glibc
 < 2.6.
Message-ID: <20150324071053.GA17372@krava.brq.redhat.com>
References: <20150320203828.GN16485@kernel.org>
 <1427137761-16119-1-git-send-email-vlee@twopensource.com>
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On Mon, Mar 23, 2015 at 12:09:16PM -0700, Vinson Lee wrote:
> From: Vinson Lee <vlee@twitter.com>
> 
> This patch fixes this build error with glibc < 2.6.
> 
>   CC       util/cloexec.o
> cc1: warnings being treated as errors
> util/cloexec.c: In function ‘perf_flag_probe’:
> util/cloexec.c:24: error: implicit declaration of function
> ‘sched_getcpu’
> util/cloexec.c:24: error: nested extern declaration of ‘sched_getcpu’
> make: *** [util/cloexec.o] Error 1
> 
> Cc: stable@vger.kernel.org # 3.18+
> Signed-off-by: Vinson Lee <vlee@twitter.com>

Acked-by: Jiri Olsa <jolsa@kernel.org>

thanks,
jirka

> ---
>  tools/perf/util/cloexec.c | 6 ++++++
>  tools/perf/util/cloexec.h | 6 ++++++
>  2 files changed, 12 insertions(+)
> 
> diff --git a/tools/perf/util/cloexec.c b/tools/perf/util/cloexec.c
> index 6da965b..85b5238 100644
> --- a/tools/perf/util/cloexec.c
> +++ b/tools/perf/util/cloexec.c
> @@ -7,6 +7,12 @@
>  
>  static unsigned long flag = PERF_FLAG_FD_CLOEXEC;
>  
> +int __weak sched_getcpu(void)
> +{
> +	errno = ENOSYS;
> +	return -1;
> +}
> +
>  static int perf_flag_probe(void)
>  {
>  	/* use 'safest' configuration as used in perf_evsel__fallback() */
> diff --git a/tools/perf/util/cloexec.h b/tools/perf/util/cloexec.h
> index 94a5a7d..68888c2 100644
> --- a/tools/perf/util/cloexec.h
> +++ b/tools/perf/util/cloexec.h
> @@ -3,4 +3,10 @@
>  
>  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 */
> -- 
> 1.8.2.1
>