* [PATCH v1 0/2] perf tool: improve error handling in perf_flag_probe()
@ 2015-03-09 12:01 Yann Droneaud
2015-03-09 12:01 ` [PATCH v1 1/2] perf tools: shortcut PERF_FLAG_FD_CLOEXEC probing in case of EBUSY error Yann Droneaud
2015-03-09 12:01 ` [PATCH v1 2/2] perf tools: report PERF_FLAG_FD_CLOEXEC probing error once Yann Droneaud
0 siblings, 2 replies; 3+ messages in thread
From: Yann Droneaud @ 2015-03-09 12:01 UTC (permalink / raw)
To: Peter Zijlstra, Paul Mackerras, Ingo Molnar,
Arnaldo Carvalho de Melo, Jiri Olsa
Cc: Yann Droneaud, Adrian Hunter, David Ahern, David Ahern,
Frederic Weisbecker, Jiri Olsa, Namhyung Kim, Peter Zijlstra,
Stephane Eranian, William Cohen, linux-kernel
Hi,
Following the EBUSY errors reported by Jiri Olsa [1], I've tryed to
improve a bit the way perf_flag_probe() handle errors.
In case EBUSY is returned by perf_event_open(), testing the function
again without PERF_FLAG_FD_CLOEXEC is meaningless: EBUSY is not
related to close-on-exec flag, so there's nothing to confirm.
For other errors, not yet explicitly handled by perf_flag_probe(),
it's pointless to report a second error message for the same error
code: the second check should not print an error if the error is
the same as the one returned for the first check.
Changes from v0 [2]:
- rebased on top of commit 48536c9195ae ("perf tools: Fix probing for PERF_FLAG_FD_CLOEXEC flag");
- update a bit commit message;
- the previous patchset was acked by Jiri[3], but I haven't
reported Acked-by: in this updated patchset.
[1] http://lkml.kernel.org/r/1406908014-8312-1-git-send-email-jolsa@kernel.org
[2] http://lkml.kernel.org/r/cover.1410595700.git.ydroneaud@opteya.com
[3] http://lkml.kernel.org/r/20140920121438.GB15481@krava.brq.redhat.com
Yann Droneaud (2):
perf tools: shortcut PERF_FLAG_FD_CLOEXEC probing in case of EBUSY
error
perf tools: report PERF_FLAG_FD_CLOEXEC probing error once
tools/perf/util/cloexec.c | 27 ++++++++++++++++-----------
1 file changed, 16 insertions(+), 11 deletions(-)
Regards.
--
Yann Droneaud
OPTEYA
^ permalink raw reply [flat|nested] 3+ messages in thread
* [PATCH v1 1/2] perf tools: shortcut PERF_FLAG_FD_CLOEXEC probing in case of EBUSY error
2015-03-09 12:01 [PATCH v1 0/2] perf tool: improve error handling in perf_flag_probe() Yann Droneaud
@ 2015-03-09 12:01 ` Yann Droneaud
2015-03-09 12:01 ` [PATCH v1 2/2] perf tools: report PERF_FLAG_FD_CLOEXEC probing error once Yann Droneaud
1 sibling, 0 replies; 3+ messages in thread
From: Yann Droneaud @ 2015-03-09 12:01 UTC (permalink / raw)
To: Peter Zijlstra, Paul Mackerras, Ingo Molnar,
Arnaldo Carvalho de Melo, Jiri Olsa
Cc: Yann Droneaud, Adrian Hunter, David Ahern, David Ahern,
Frederic Weisbecker, Jiri Olsa, Namhyung Kim, Peter Zijlstra,
Stephane Eranian, William Cohen, linux-kernel
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.1425901229.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 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;
+
+ 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)));
@@ -64,7 +68,7 @@ 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;
--
2.1.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* [PATCH v1 2/2] perf tools: report PERF_FLAG_FD_CLOEXEC probing error once
2015-03-09 12:01 [PATCH v1 0/2] perf tool: improve error handling in perf_flag_probe() Yann Droneaud
2015-03-09 12:01 ` [PATCH v1 1/2] perf tools: shortcut PERF_FLAG_FD_CLOEXEC probing in case of EBUSY error Yann Droneaud
@ 2015-03-09 12:01 ` Yann Droneaud
1 sibling, 0 replies; 3+ messages in thread
From: Yann Droneaud @ 2015-03-09 12:01 UTC (permalink / raw)
To: Peter Zijlstra, Paul Mackerras, Ingo Molnar,
Arnaldo Carvalho de Melo, Jiri Olsa
Cc: Yann Droneaud, Adrian Hunter, David Ahern, David Ahern,
Frederic Weisbecker, Jiri Olsa, Namhyung Kim, Peter Zijlstra,
Stephane Eranian, William Cohen, linux-kernel
In case of failure, unrelated to PERF_FLAG_FD_CLOEXEC,
perf_flag_probe() reports the error twice. For example:
$ perf record ls
Error:
perf_event_open(..., PERF_FLAG_FD_CLOEXEC) failed with unexpected error 16 (Device or resource busy)
perf_event_open(..., 0) failed unexpectedly with error 16 (Device or resource busy)
There's no need for the second error message, so this
patch changes the function to only report a second
error message if the two calls to perf_even_open(2)
fail with different error codes.
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.1425901229.git.ydroneaud@opteya.com
Reported-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Yann Droneaud <ydroneaud@opteya.com>
---
tools/perf/util/cloexec.c | 25 +++++++++++++------------
1 file changed, 13 insertions(+), 12 deletions(-)
diff --git a/tools/perf/util/cloexec.c b/tools/perf/util/cloexec.c
index 2f05f8f8c22e..60bfa8ad45f3 100644
--- a/tools/perf/util/cloexec.c
+++ b/tools/perf/util/cloexec.c
@@ -16,7 +16,7 @@ static int perf_flag_probe(void)
.exclude_kernel = 1,
};
int fd;
- int err;
+ int err0, err1;
int cpu;
pid_t pid = -1;
char sbuf[STRERR_BUFSIZE];
@@ -39,7 +39,7 @@ static int perf_flag_probe(void)
}
break;
}
- err = errno;
+ err0 = errno;
if (fd >= 0) {
close(fd);
@@ -47,12 +47,12 @@ static int perf_flag_probe(void)
}
/* ignore busy errors */
- if (err == EBUSY)
+ if (err0 == EBUSY)
return -1;
- WARN_ONCE(err != EINVAL,
+ WARN_ONCE(err0 != EINVAL,
"perf_event_open(..., PERF_FLAG_FD_CLOEXEC) failed with unexpected error %d (%s)\n",
- err, strerror_r(err, sbuf, sizeof(sbuf)));
+ err0, strerror_r(err0, sbuf, sizeof(sbuf)));
/* not supported, confirm error related to PERF_FLAG_FD_CLOEXEC */
while (1) {
@@ -63,17 +63,18 @@ static int perf_flag_probe(void)
}
break;
}
- err = errno;
+ err1 = errno;
- if (fd >= 0)
+ if (fd >= 0) {
close(fd);
+ return 0;
+ }
- 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;
+ WARN_ONCE(err0 != err1,
+ "perf_event_open(..., 0) failed unexpectedly with error %d (%s)\n",
+ err1, strerror_r(err1, sbuf, sizeof(sbuf)));
- return 0;
+ return -1;
}
unsigned long perf_event_open_cloexec_flag(void)
--
2.1.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
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2015-03-09 12:01 [PATCH v1 0/2] perf tool: improve error handling in perf_flag_probe() Yann Droneaud
2015-03-09 12:01 ` [PATCH v1 1/2] perf tools: shortcut PERF_FLAG_FD_CLOEXEC probing in case of EBUSY error Yann Droneaud
2015-03-09 12:01 ` [PATCH v1 2/2] perf tools: report PERF_FLAG_FD_CLOEXEC probing error once Yann Droneaud
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