[PATCH v2] perf test stat_all_pmu.sh: Parse return value of perf stat

[vmolnaro@redhat.com]

From: Veronika Molnarova <vmolnaro@redhat.com>

With the upstream MR !3916 of commit a381bd3615de6 ('powerpc/hv-gpci:
Fix the H_GET_PERF_COUNTER_INFO hcall return value checks') the perf
stat for hv_gpci events without required permission set returns an
error value of -1 to differentiate the output from the unsupported
events. The stat_all_pmu test was designed in a way, that if any
command exits with a non-zero value the test exits with an error
value without any information provided due to the 'set -e' option.

Running stat_all_pmu test on powerpc machine with unsupported hv_gpci
event causes failure after the MR as the zero return value was required.
The issue propagated upstream as the list of the files that affected perf
did not cover the changed files and was updated after the issue was
discovered. It was caught by CKI testing where it was triaged to stop
blocking further MRs, as most of the powerpc machines do not support
some of the hv_gpci events.

Remove the 'set -e' option from the test and rework the test case to log
the status of the event for better maintainability. Instead of exiting
immediately after 'perf stat' ends with a non-zero value, check the
return value and output of the 'perf stat' command with the appropriate action.

Link to the MR !3916 of commit a381bd3615de6:
https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/3916

Signed-off-by: Veronika Molnarova <vmolnaro@redhat.com>
---
 tools/perf/tests/shell/stat_all_pmu.sh | 36 ++++++++++++++++++--------
 1 file changed, 25 insertions(+), 11 deletions(-)

diff --git a/tools/perf/tests/shell/stat_all_pmu.sh b/tools/perf/tests/shell/stat_all_pmu.sh
index c77955419173..d9f0d2100baa 100755
--- a/tools/perf/tests/shell/stat_all_pmu.sh
+++ b/tools/perf/tests/shell/stat_all_pmu.sh
@@ -2,21 +2,35 @@
 # perf all PMU test
 # SPDX-License-Identifier: GPL-2.0
 
-set -e
 
 # Test all PMU events; however exclude parametrized ones (name contains '?')
 for p in $(perf list --raw-dump pmu | sed 's/[[:graph:]]\+?[[:graph:]]\+[[:space:]]//g'); do
-  echo "Testing $p"
-  result=$(perf stat -e "$p" true 2>&1)
-  if ! echo "$result" | grep -q "$p" && ! echo "$result" | grep -q "<not supported>" ; then
-    # We failed to see the event and it is supported. Possibly the workload was
-    # too small so retry with something longer.
-    result=$(perf stat -e "$p" perf bench internals synthesize 2>&1)
-    if ! echo "$result" | grep -q "$p" ; then
-      echo "Event '$p' not printed in:"
-      echo "$result"
-      exit 1
+  echo -n "Testing event '$p' -- "
+  stat_output=$(perf stat -e "$p" true 2>&1)
+  stat_result=$?
+  if echo "$stat_output" | grep -q "$p"; then
+    # return value 0 if counters gets printed either if the event is supported or not
+    if [ $stat_result -eq 0 ] && ! echo "$stat_output" | grep -q "<not supported>"; then
+        echo "supported"
+    elif [ $stat_result -eq 0 ]; then
+        echo "not supported"
+    # return value 255 when the required pemission for the event is not set
+    elif [ $stat_result -eq 255 ] && echo "$stat_output" | grep -q "No permission"; then
+        echo "no permission to enable"
+    # return value 129 when trying to run 'perf stat' with a non-existent event
+    elif [ $stat_result -eq 129 ] && echo "$stat_output" | grep -q "Bad event name"; then
+        echo "Fail: Bad event name"
+        echo "$stat_output"
+        exit 1
+    else
+        echo "Fail: Unknown return value $stat_result"
+        echo "$stat_output"
+        exit 1
     fi
+  else
+      echo "Fail: Event '$p' not printed in:"
+      echo "$stat_output"
+      exit 1
   fi
 done
 
-- 
2.43.0