[PATCH v1 1/2] perf tools: shortcut PERF_FLAG_FD_CLOEXEC probing in case of EBUSY error

From: Yann Droneaud
Date: Mon Mar 09 2015 - 08:04:15 EST

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

Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Cc: William Cohen <wcohen@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/cover.1425901229.git.ydroneaud@xxxxxxxxxx
Signed-off-by: Yann Droneaud <ydroneaud@xxxxxxxxxx>
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 6da965bdbc2c..2f05f8f8c22e 100644
--- a/tools/perf/util/cloexec.c
+++ b/tools/perf/util/cloexec.c
@@ -46,7 +46,11 @@ static int perf_flag_probe(void)
return 1;

- WARN_ONCE(err != EINVAL && err != EBUSY,
+ /* ignore busy errors */
+ if (err == EBUSY)
+ return -1;
"perf_event_open(..., PERF_FLAG_FD_CLOEXEC) failed with unexpected error %d (%s)\n",
err, strerror_r(err, sbuf, sizeof(sbuf)));

@@ -64,7 +68,7 @@ static int perf_flag_probe(void)
if (fd >= 0)

- 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;

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