[PATCH 5/5] perf tests: Fix record+probe_libc_inet_pton.sh when event exists

[Sandipan Das]

If the event 'probe_libc:inet_pton' already exists, this test
fails and deletes the existing event before exiting. This will
then pass for any subsequent executions.

Instead of skipping to deleting the existing event because of
failing to add a new event, a duplicate event is now created
and the script continues with the usual checks. Only the new
duplicate event that is created at the beginning of the test
is deleted as a part of the cleanups in the end. All existing
events remain as it is.

This can be observed on a powerpc64 system running Fedora 27 as
shown below.

  # perf probe -x /usr/lib64/power8/libc-2.26.so -a inet_pton

  Added new event:
    probe_libc:inet_pton (on inet_pton in /usr/lib64/power8/libc-2.26.so)

Before:

  # perf test -v "probe libc's inet_pton & backtrace it with ping"

  62: probe libc's inet_pton & backtrace it with ping       :
  --- start ---
  test child forked, pid 21302
  test child finished with -1
  ---- end ----
  probe libc's inet_pton & backtrace it with ping: FAILED!

  # perf probe --list

After:

  # perf test -v "probe libc's inet_pton & backtrace it with ping"

  62: probe libc's inet_pton & backtrace it with ping       :
  --- start ---
  test child forked, pid 21490
  ping 21513 [035] 39357.565561: probe_libc:inet_pton_1: (7fffa4c623b0)
  7fffa4c623b0 __GI___inet_pton+0x0 (/usr/lib64/power8/libc-2.26.so)
  7fffa4c190dc gaih_inet.constprop.7+0xf4c (/usr/lib64/power8/libc-2.26.so)
  7fffa4c19c4c getaddrinfo+0x15c (/usr/lib64/power8/libc-2.26.so)
  111d93c20 main+0x3e0 (/usr/bin/ping)
  test child finished with 0
  ---- end ----
  probe libc's inet_pton & backtrace it with ping: Ok

  # perf probe --list

    probe_libc:inet_pton (on __inet_pton@resolv/inet_pton.c in /usr/lib64/power8/libc-2.26.so)

Signed-off-by: Sandipan Das <sandipan@xxxxxxxxxxxxx>
---
 .../tests/shell/record+probe_libc_inet_pton.sh     | 28 ++++++++++++++++++----
 1 file changed, 24 insertions(+), 4 deletions(-)

diff --git a/tools/perf/tests/shell/record+probe_libc_inet_pton.sh b/tools/perf/tests/shell/record+probe_libc_inet_pton.sh
index 0502a9e04c79..3013ac8f83d0 100755
--- a/tools/perf/tests/shell/record+probe_libc_inet_pton.sh
+++ b/tools/perf/tests/shell/record+probe_libc_inet_pton.sh
@@ -13,11 +13,24 @@
 libc=$(grep -w libc /proc/self/maps | head -1 | sed -r 's/.*[[:space:]](\/.*)/\1/g')
 nm -Dg $libc 2>/dev/null | fgrep -q inet_pton || exit 254
 
+event_pattern='probe_libc:inet_pton(\_[[:digit:]]+)?'
+
+add_libc_inet_pton_event() {
+
+	event_name=$(perf probe -f -x $libc -a inet_pton 2>&1 | tail -n +2 | head -n -5 | \
+			grep -P -o "$event_pattern(?=[[:space:]]\(on inet_pton in $libc\))")
+
+	if [ $? -ne 0 -o -z "$event_name" ] ; then
+		printf "FAIL: could not add event\n"
+		return 1
+	fi
+}
+
 trace_libc_inet_pton_backtrace() {
 
 	expected=`mktemp -u /tmp/expected.XXX`
 
-	echo "ping[][0-9 \.:]+probe_libc:inet_pton: \([[:xdigit:]]+\)" > $expected
+	echo "ping[][0-9 \.:]+$event_name: \([[:xdigit:]]+\)" > $expected
 	echo ".*inet_pton\+0x[[:xdigit:]]+[[:space:]]\($libc|inlined\)$" >> $expected
 	case "$(uname -m)" in
 	s390x)
@@ -41,7 +54,7 @@ trace_libc_inet_pton_backtrace() {
 
 	perf_data=`mktemp -u /tmp/perf.data.XXX`
 	perf_script=`mktemp -u /tmp/perf.script.XXX`
-	perf record -e probe_libc:inet_pton/$eventattr/ -o $perf_data ping -6 -c 1 ::1 > /dev/null 2>&1
+	perf record -e $event_name/$eventattr/ -o $perf_data ping -6 -c 1 ::1 > /dev/null 2>&1
 	perf script -i $perf_data > $perf_script
 
 	exec 3<$perf_script
@@ -62,13 +75,20 @@ trace_libc_inet_pton_backtrace() {
 	# even if the perf script output does not match.
 }
 
+delete_libc_inet_pton_event() {
+
+	if [ -n "$event_name" ] ; then
+		perf probe -q -d $event_name
+	fi
+}
+
 # Check for IPv6 interface existence
 ip a sh lo | fgrep -q inet6 || exit 2
 
 skip_if_no_perf_probe && \
-perf probe -q $libc inet_pton && \
+add_libc_inet_pton_event && \
 trace_libc_inet_pton_backtrace
 err=$?
 rm -f ${perf_data} ${perf_script} ${expected}
-perf probe -q -d probe_libc:inet_pton
+delete_libc_inet_pton_event
 exit $err
-- 
2.14.4