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[PATCH v2 1/2] perf tools: shortcut PERF_FLAG_FD_CLOEXEC probing in case of EBUSY error

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This patch is a simplification of the logic introduced as part of
commit 63914aca8f7e ('perf tools: Show better error message in case we fail to open counters due to EBUSY error'):
if EBUSY is reported by perf_event_open(), it will not be possible
to probe PERF_FLAG_FD_CLOEXEC, so it's safe to leave early.

It should be noted that -EBUSY errors are not really expected here
since commit 038fa0b9739d ('perf tools: Fix PERF_FLAG_FD_CLOEXEC flag probing event type open counters due to EBUSY error'):
the perf event type used now should be safe to use regarding -EBUSY
error.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: William Cohen <wcohen@redhat.com>
Link: http://lkml.kernel.org/r/cover.1443708092.git.ydroneaud@opteya.com
Signed-off-by: Yann Droneaud <ydroneaud@opteya.com>
---
 tools/perf/util/cloexec.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/cloexec.c b/tools/perf/util/cloexec.c
index 2babddaa2481..be226d293c91 100644
--- a/tools/perf/util/cloexec.c
+++ b/tools/perf/util/cloexec.c
@@ -56,7 +56,11 @@ static int perf_flag_probe(void)
 		return 1;
 	}
 
-	WARN_ONCE(err != EINVAL && err != EBUSY,
+	/* ignore busy errors */
+	if (err == EBUSY)
+		return -1;
+
+	WARN_ONCE(err != EINVAL,
 		  "perf_event_open(..., PERF_FLAG_FD_CLOEXEC) failed with unexpected error %d (%s)\n",
 		  err, strerror_r(err, sbuf, sizeof(sbuf)));
 
@@ -74,7 +78,7 @@ static int perf_flag_probe(void)
 	if (fd >= 0)
 		close(fd);
 
-	if (WARN_ONCE(fd < 0 && err != EBUSY,
+	if (WARN_ONCE(fd < 0,
 		      "perf_event_open(..., 0) failed unexpectedly with error %d (%s)\n",
 		      err, strerror_r(err, sbuf, sizeof(sbuf))))
 		return -1;
-- 
2.4.3

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[PATCH v2 0/2] perf tool: improve error handling in perf_flag_probe() Yann Droneaud <ydroneaud@opteya.com> - 2015-10-01 17:20 +0200
  [PATCH v2 2/2] perf tools: report PERF_FLAG_FD_CLOEXEC probing error once Yann Droneaud <ydroneaud@opteya.com> - 2015-10-01 17:20 +0200
    Re: [PATCH v2 2/2] perf tools: report PERF_FLAG_FD_CLOEXEC probing  error once Yann Droneaud <ydroneaud@opteya.com> - 2015-10-02 15:50 +0200
  [PATCH v2 1/2] perf tools: shortcut PERF_FLAG_FD_CLOEXEC probing in case of EBUSY error Yann Droneaud <ydroneaud@opteya.com> - 2015-10-01 17:20 +0200
    Re: [PATCH v2 1/2] perf tools: shortcut PERF_FLAG_FD_CLOEXEC  probing in case of EBUSY error Yann Droneaud <ydroneaud@opteya.com> - 2015-10-01 23:40 +0200
      Re: [PATCH v2 1/2] perf tools: shortcut PERF_FLAG_FD_CLOEXEC probing  in case of EBUSY error Jiri Olsa <jolsa@redhat.com> - 2015-10-02 15:20 +0200

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