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

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Date:	Thu, 23 Jul 2015 13:16:55 -0400 (EDT)
From:	Vince Weaver <vincent.weaver@...ne.edu>
To:	"Michael Kerrisk (man-pages)" <mtk.manpages@...il.com>
cc:	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, Vince Weaver <vincent.weaver@...ne.edu>
Subject: [patch 11/11] perf_event_open.2: add possibility of EBUSY error


Linux 4.1 added the possibility of perf_event_open() returning
EBUSY if an existing exclusive event controls the PMU.

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
--
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