linux-kernel - Re: [patch 11/11] perf_event_open.2: add possibility of EBUSY error

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Date:	Wed, 14 Oct 2015 08:47:39 +0200
From:	"Michael Kerrisk (man-pages)" <mtk.manpages@...il.com>
To:	Vince Weaver <vincent.weaver@...ne.edu>
CC:	mtk.manpages@...il.com, linux-man@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Borislav Petkov <bp@...en8.de>,
	Frederic Weisbecker <fweisbec@...il.com>,
	"H. Peter Anvin" <hpa@...or.com>, Kaixu Xia <kaixu.xia@...aro.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Mike Galbraith <efault@....de>,
	Robert Richter <rric@...nel.org>,
	Stephane Eranian <eranian@...gle.com>,
	Thomas Gleixner <tglx@...utronix.de>, adrian.hunter@...el.com,
	kan.liang@...el.com, markus.t.metzger@...el.com,
	mathieu.poirier@...aro.org
Subject: Re: [patch 11/11] perf_event_open.2: add possibility of EBUSY error

On 07/23/2015 07:16 PM, Vince Weaver wrote:
> 
> Linux 4.1 added the possibility of perf_event_open() returning
> EBUSY if an existing exclusive event controls the PMU.

Thanks, Vince. Applied.

Cheers,

Michael


> This was introduced by the following commit:
> 
> 	commit bed5b25ad9c8a2f5d735ef0bc746ec870c01c1b0
> 	Author: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
> 	Date:   Fri Jan 30 12:31:06 2015 +0200
> 
> 	perf: Add a pmu capability for "exclusive" events
> 
> 	Signed-off-by: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
> 	Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> 	Cc: Borislav Petkov <bp@...en8.de>
> 	Cc: Frederic Weisbecker <fweisbec@...il.com>
> 	Cc: H. Peter Anvin <hpa@...or.com>
> 	Cc: Kaixu Xia <kaixu.xia@...aro.org>
> 	Cc: Linus Torvalds <torvalds@...ux-foundation.org>
> 	Cc: Mike Galbraith <efault@....de>
> 	Cc: Paul Mackerras <paulus@...ba.org>
> 	Cc: Robert Richter <rric@...nel.org>
> 	Cc: Stephane Eranian <eranian@...gle.com>
> 	Cc: Thomas Gleixner <tglx@...utronix.de>
> 	Cc: acme@...radead.org
> 	Cc: adrian.hunter@...el.com
> 	Cc: kan.liang@...el.com
> 	Cc: markus.t.metzger@...el.com
> 	Cc: mathieu.poirier@...aro.org
> 
> Signed-off-by: Vince Weaver <vincent.weaver@...ne.edu>
> 
> diff --git a/man2/perf_event_open.2 b/man2/perf_event_open.2
> index b3cd93f..3d03786 100644
> --- a/man2/perf_event_open.2
> +++ b/man2/perf_event_open.2
> @@ -2911,6 +2911,11 @@ the cgroup file descriptor in
>  .I pid
>  is not valid.
>  .TP
> +.BR EBUSY " (since Linux 4.1)"
> +.\" bed5b25ad9c8a2f5d735ef0bc746ec870c01c1b0
> +Returned if another event already has exclusive
> +access to the PMU.
> +.TP
>  .B EFAULT
>  Returned if the
>  .I attr
> 


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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