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From:   Sasha Levin <Alexander.Levin@microsoft.com>
To:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "stable@vger.kernel.org" <stable@vger.kernel.org>
CC:     Stephane Eranian <eranian@google.com>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Andi Kleen <ak@linux.intel.com>,
        Mathieu Poirier <mathieu.poirier@linaro.org>,
        Paul Turner <pjt@google.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Wang Nan <wangnan0@huawei.com>,
        Arnaldo Carvalho de Melo <acme@redhat.com>,
        Sasha Levin <Alexander.Levin@microsoft.com>
Subject: [PATCH AUTOSEL for 4.9 169/219] perf stat: Fix bug in handling events
 in error state
Thread-Topic: [PATCH AUTOSEL for 4.9 169/219] perf stat: Fix bug in handling
 events in error state
Thread-Index: AQHTsz8bBwlRahIClE2EJ/yaNZU72w==
Date:   Sat, 3 Mar 2018 22:29:35 +0000
Message-ID: <20180303222716.26640-169-alexander.levin@microsoft.com>
References: <20180303222716.26640-1-alexander.levin@microsoft.com>
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From: Stephane Eranian <eranian@google.com>

[ Upstream commit db49a71798a38f3ddf3f3462703328dca39b1ac7 ]

(This is a patch has been sitting in the Intel CQM/CMT driver series for
 a while, despite not depend on it. Sending it now independently since
 the series is being discarded.)

When an event is in error state, read() returns 0 instead of sizeof()
buffer. In certain modes, such as interval printing, ignoring the 0
return value may cause bogus count deltas to be computed and thus
invalid results printed.

This patch fixes this problem by modifying read_counters() to mark the
event as not scaled (scaled =3D -1) to force the printout routine to show
<NOT COUNTED>.

Signed-off-by: Stephane Eranian <eranian@google.com>
Reviewed-by: David Carrillo-Cisneros <davidcc@google.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/20170412182301.44406-1-davidcc@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
 tools/perf/builtin-stat.c | 12 +++++++++---
 tools/perf/util/evsel.c   |  4 ++--
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index c241167c76c9..5b60ec669e73 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -311,8 +311,12 @@ static int read_counter(struct perf_evsel *counter)
 			struct perf_counts_values *count;
=20
 			count =3D perf_counts(counter->counts, cpu, thread);
-			if (perf_evsel__read(counter, cpu, thread, count))
+			if (perf_evsel__read(counter, cpu, thread, count)) {
+				counter->counts->scaled =3D -1;
+				perf_counts(counter->counts, cpu, thread)->ena =3D 0;
+				perf_counts(counter->counts, cpu, thread)->run =3D 0;
 				return -1;
+			}
=20
 			if (STAT_RECORD) {
 				if (perf_evsel__write_stat_event(counter, cpu, thread, count)) {
@@ -337,12 +341,14 @@ static int read_counter(struct perf_evsel *counter)
 static void read_counters(void)
 {
 	struct perf_evsel *counter;
+	int ret;
=20
 	evlist__for_each_entry(evsel_list, counter) {
-		if (read_counter(counter))
+		ret =3D read_counter(counter);
+		if (ret)
 			pr_debug("failed to read counter %s\n", counter->name);
=20
-		if (perf_stat_process_counter(&stat_config, counter))
+		if (ret =3D=3D 0 && perf_stat_process_counter(&stat_config, counter))
 			pr_warning("failed to process counter %s\n", counter->name);
 	}
 }
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 539724c7d30b..bce80f866dd0 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1221,7 +1221,7 @@ int perf_evsel__read(struct perf_evsel *evsel, int cp=
u, int thread,
 	if (FD(evsel, cpu, thread) < 0)
 		return -EINVAL;
=20
-	if (readn(FD(evsel, cpu, thread), count, sizeof(*count)) < 0)
+	if (readn(FD(evsel, cpu, thread), count, sizeof(*count)) <=3D 0)
 		return -errno;
=20
 	return 0;
@@ -1239,7 +1239,7 @@ int __perf_evsel__read_on_cpu(struct perf_evsel *evse=
l,
 	if (evsel->counts =3D=3D NULL && perf_evsel__alloc_counts(evsel, cpu + 1,=
 thread + 1) < 0)
 		return -ENOMEM;
=20
-	if (readn(FD(evsel, cpu, thread), &count, nv * sizeof(u64)) < 0)
+	if (readn(FD(evsel, cpu, thread), &count, nv * sizeof(u64)) <=3D 0)
 		return -errno;
=20
 	perf_evsel__compute_deltas(evsel, cpu, thread, &count);
--=20
2.14.1