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perf evsel: Always preserve errno while cleaning up perf_event_open failures

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In some cases when perf_event_open fails, it may do some closes to clean
up. In special cases these closes can fail too, which overwrites the
errno of the perf_event_open, which is then incorrectly reported.

Save/restore errno around closes.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lore.kernel.org/lkml/20191020175202.32456-2-andi@firstfloor.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Andi Kleen 2019-10-20 10:51:54 -07:00 committed by Arnaldo Carvalho de Melo
parent 9d604aad4b
commit 796c01a4bf
1 changed files with 4 additions and 2 deletions
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6
tools/perf/util/evsel.c
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@ -1574,7 +1574,7 @@ int evsel__open(struct evsel *evsel, struct perf_cpu_map *cpus,
{ {
int cpu, thread, nthreads; int cpu, thread, nthreads;
unsigned long flags = PERF_FLAG_FD_CLOEXEC; unsigned long flags = PERF_FLAG_FD_CLOEXEC;
int pid = -1, err; int pid = -1, err, old_errno;
enum { NO_CHANGE, SET_TO_MAX, INCREASED_MAX } set_rlimit = NO_CHANGE; enum { NO_CHANGE, SET_TO_MAX, INCREASED_MAX } set_rlimit = NO_CHANGE;
if ((perf_missing_features.write_backward && evsel->core.attr.write_backward) || if ((perf_missing_features.write_backward && evsel->core.attr.write_backward) ||
@ -1727,8 +1727,8 @@ try_fallback:
*/ */
if (err == -EMFILE && set_rlimit < INCREASED_MAX) { if (err == -EMFILE && set_rlimit < INCREASED_MAX) {
struct rlimit l; struct rlimit l;
int old_errno = errno;
old_errno = errno;
if (getrlimit(RLIMIT_NOFILE, &l) == 0) { if (getrlimit(RLIMIT_NOFILE, &l) == 0) {
if (set_rlimit == NO_CHANGE) if (set_rlimit == NO_CHANGE)
l.rlim_cur = l.rlim_max; l.rlim_cur = l.rlim_max;
@ -1812,6 +1812,7 @@ out_close:
if (err) if (err)
threads->err_thread = thread; threads->err_thread = thread;
old_errno = errno;
do { do {
while (--thread >= 0) { while (--thread >= 0) {
close(FD(evsel, cpu, thread)); close(FD(evsel, cpu, thread));
@ -1819,6 +1820,7 @@ out_close:
} }
thread = nthreads; thread = nthreads;
} while (--cpu >= 0); } while (--cpu >= 0);
errno = old_errno;
return err; return err;
} }