* [PATCH v2 0/2] perf tool: improve error handling in perf_flag_probe()
@ 2015-10-01 15:16 Yann Droneaud
2015-10-01 15:18 ` [PATCH v2 1/2] perf tools: shortcut PERF_FLAG_FD_CLOEXEC probing in case of EBUSY error Yann Droneaud
2015-10-01 15:18 ` [PATCH v2 2/2] perf tools: report PERF_FLAG_FD_CLOEXEC probing error once Yann Droneaud
0 siblings, 2 replies; 6+ messages in thread
From: Yann Droneaud @ 2015-10-01 15:16 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 v1 [2]:
- resend
Changes from v0 [3]:
- 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[4], 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.1425901229.git.ydroneaud@opteya.com
[3] http://lkml.kernel.org/r/cover.1410595700.git.ydroneaud@opteya.com
[4] 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(-)
--
2.4.3
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH v2 1/2] perf tools: shortcut PERF_FLAG_FD_CLOEXEC probing in case of EBUSY error
2015-10-01 15:16 [PATCH v2 0/2] perf tool: improve error handling in perf_flag_probe() Yann Droneaud
@ 2015-10-01 15:18 ` Yann Droneaud
[not found] ` <20151001205247.GA4445@krava.redhat.com>
2015-10-01 15:18 ` [PATCH v2 2/2] perf tools: report PERF_FLAG_FD_CLOEXEC probing error once Yann Droneaud
1 sibling, 1 reply; 6+ messages in thread
From: Yann Droneaud @ 2015-10-01 15:18 UTC (permalink / raw)
To: 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.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
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH v2 2/2] perf tools: report PERF_FLAG_FD_CLOEXEC probing error once
2015-10-01 15:16 [PATCH v2 0/2] perf tool: improve error handling in perf_flag_probe() Yann Droneaud
2015-10-01 15:18 ` [PATCH v2 1/2] perf tools: shortcut PERF_FLAG_FD_CLOEXEC probing in case of EBUSY error Yann Droneaud
@ 2015-10-01 15:18 ` Yann Droneaud
[not found] ` <20151002132041.GB1673@krava.brq.redhat.com>
1 sibling, 1 reply; 6+ messages in thread
From: Yann Droneaud @ 2015-10-01 15:18 UTC (permalink / raw)
To: 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 when 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.1443708092.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 be226d293c91..552528698566 100644
--- a/tools/perf/util/cloexec.c
+++ b/tools/perf/util/cloexec.c
@@ -26,7 +26,7 @@ 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];
@@ -49,7 +49,7 @@ static int perf_flag_probe(void)
}
break;
}
- err = errno;
+ err0 = errno;
if (fd >= 0) {
close(fd);
@@ -57,12 +57,12 @@ 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) {
@@ -73,17 +73,18 @@ 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)
--
2.4.3
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH v2 1/2] perf tools: shortcut PERF_FLAG_FD_CLOEXEC probing in case of EBUSY error
[not found] ` <20151001205247.GA4445@krava.redhat.com>
@ 2015-10-01 21:32 ` Yann Droneaud
2015-10-02 13:19 ` Jiri Olsa
0 siblings, 1 reply; 6+ messages in thread
From: Yann Droneaud @ 2015-10-01 21:32 UTC (permalink / raw)
To: Jiri Olsa
Cc: Adrian Hunter, David Ahern, Frederic Weisbecker, Jiri Olsa,
Namhyung Kim, Paul Mackerras, Peter Zijlstra, Stephane Eranian,
William Cohen, linux-kernel
Hi,
Le jeudi 01 octobre 2015 à 22:52 +0200, Jiri Olsa a écrit :
> On Thu, Oct 01, 2015 at 05:16:25PM +0200, Yann Droneaud wrote:
> > 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;
>
> so what's now the error message in case we get EBUSY ?
>
None, just as it does currently.
perf_event_open_cloexec_flag() will still will return 0 just like
PERF_FLAG_FD_CLOEXEC was not available.
Handling -EBUSY is left to the function which will try to make use of
perf_event_open().
Regards.
--
Yann Droneaud
OPTEYA
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2 1/2] perf tools: shortcut PERF_FLAG_FD_CLOEXEC probing in case of EBUSY error
2015-10-01 21:32 ` Yann Droneaud
@ 2015-10-02 13:19 ` Jiri Olsa
0 siblings, 0 replies; 6+ messages in thread
From: Jiri Olsa @ 2015-10-02 13:19 UTC (permalink / raw)
To: Yann Droneaud
Cc: Adrian Hunter, David Ahern, Frederic Weisbecker, Jiri Olsa,
Namhyung Kim, Paul Mackerras, Peter Zijlstra, Stephane Eranian,
William Cohen, linux-kernel
On Thu, Oct 01, 2015 at 11:32:16PM +0200, Yann Droneaud wrote:
> Hi,
>
> Le jeudi 01 octobre 2015 à 22:52 +0200, Jiri Olsa a écrit :
> > On Thu, Oct 01, 2015 at 05:16:25PM +0200, Yann Droneaud wrote:
> > > 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;
> >
> > so what's now the error message in case we get EBUSY ?
> >
>
> None, just as it does currently.
>
> perf_event_open_cloexec_flag() will still will return 0 just like
> PERF_FLAG_FD_CLOEXEC was not available.
>
> Handling -EBUSY is left to the function which will try to make use of
> perf_event_open().
I see, ook
Acked-by: Jiri Olsa <jolsa@kernel.org>
thanks,
jirka
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2 2/2] perf tools: report PERF_FLAG_FD_CLOEXEC probing error once
[not found] ` <20151002132041.GB1673@krava.brq.redhat.com>
@ 2015-10-02 13:43 ` Yann Droneaud
0 siblings, 0 replies; 6+ messages in thread
From: Yann Droneaud @ 2015-10-02 13:43 UTC (permalink / raw)
To: Jiri Olsa
Cc: Adrian Hunter, David Ahern, Frederic Weisbecker, Jiri Olsa,
Namhyung Kim, Paul Mackerras, Peter Zijlstra, Stephane Eranian,
William Cohen, linux-kernel
Le vendredi 02 octobre 2015 à 15:20 +0200, Jiri Olsa a écrit :
> On Thu, Oct 01, 2015 at 05:16:26PM +0200, Yann Droneaud wrote:
> > 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)
>
> so this error message is no longer possible due to your earlier patch
> right?
>
My bad, the error used to illustrate the behavior is not well choosed.
> could you please provide current 'before&after' output into changelog
> otherwise it looks ok
>
OK. I'm updating the message.
Regards.
--
Yann Droneaud
OPTEYA
^ permalink raw reply [flat|nested] 6+ messages in thread
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