perf evsel: Always preserve errno while cleaning up perf_event_open failures (796c01a4) · Commits · 戴 / test

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>

tools/perf/util/evsel.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -1574,7 +1574,7 @@ int evsel__open(struct evsel evsel, struct perf_cpu_map cpus,
		{
		int cpu, thread, nthreads;
		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;

		if ((perf_missing_features.write_backward && evsel->core.attr.write_backward) \|\|
		@@ -1727,8 +1727,8 @@ try_fallback:
		*/
		if (err == -EMFILE && set_rlimit < INCREASED_MAX) {
		struct rlimit l;
		int old_errno = errno;

		old_errno = errno;
		if (getrlimit(RLIMIT_NOFILE, &l) == 0) {
		if (set_rlimit == NO_CHANGE)
		l.rlim_cur = l.rlim_max;
		@@ -1812,6 +1812,7 @@ out_close:
		if (err)
		threads->err_thread = thread;

		old_errno = errno;
		do {
		while (--thread >= 0) {
		close(FD(evsel, cpu, thread));
		@@ -1819,6 +1820,7 @@ out_close:
		}
		thread = nthreads;
		} while (--cpu >= 0);
		errno = old_errno;
		return err;
		}

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