[PATCH v6 22/26] perf test record+probe_libc_inet_pton: Scope event to PID and make non-exclusive

[Ian Rogers]

Scope the uprobe name to the pid, retry adding and deleting it as
concurrent uprobe_events writes can fail with EBUSY, and delete it from
an exit trap. Create the temporary files with mktemp rather than reserving
names with mktemp -u. Remove the exclusive tag.

Assisted-by: Antigravity:gemini-3.1-pro
Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
---
 .../shell/record+probe_libc_inet_pton.sh      | 85 ++++++++++++++-----
 1 file changed, 65 insertions(+), 20 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 4c9a308a450d..3a363a99ef41 100755
--- a/tools/perf/tests/shell/record+probe_libc_inet_pton.sh
+++ b/tools/perf/tests/shell/record+probe_libc_inet_pton.sh
@@ -1,5 +1,5 @@
 #!/bin/bash
-# probe libc's inet_pton & backtrace it with ping (exclusive)
+# probe libc's inet_pton & backtrace it with ping
 
 # Installs a probe on libc's inet_pton function, that will use uprobes,
 # then use 'perf trace' on a ping to localhost asking for just one packet
@@ -19,20 +19,27 @@ nm -Dg $libc 2>/dev/null | grep -F -q inet_pton || exit 254
 event_pattern='probe_libc:inet_pton(_[[:digit:]]+)?'
 
 add_libc_inet_pton_event() {
+	local attempts=0
+	while [ $attempts -lt 3 ]; do
+		event_name=$(perf probe -f -x $libc -a "inet_pton_$$=inet_pton" 2>&1 | \
+				awk -v ep="$event_pattern" -v l="$libc" '$0 ~ ep && $0 ~ \
+				("\\(on inet_pton in " l "\\)") {print $1}' | head -n 1)
+
+		if [ -n "$event_name" ]; then
+			return 0
+		fi
+		attempts=$((attempts + 1))
+		sleep 0.1
+	done
 
-	event_name=$(perf probe -f -x $libc -a inet_pton 2>&1 | \
-			awk -v ep="$event_pattern" -v l="$libc" '$0 ~ ep && $0 ~ \
-			("\\(on inet_pton in " l "\\)") {print $1}' | head -n 1)
-
-	if [ $? -ne 0 ] || [ -z "$event_name" ] ; then
-		printf "FAIL: could not add event\n"
-		return 1
-	fi
+	printf "FAIL: could not add event\n"
+	return 1
 }
 
 trace_libc_inet_pton_backtrace() {
 
-	expected=`mktemp -u /tmp/expected.XXX`
+	# Create the files, as root a reserved /tmp name could be a planted symlink.
+	expected=$(mktemp /tmp/expected.XXX) || return 1
 
 	echo "ping[][0-9 \.:]+$event_name: \([[:xdigit:]]+\)" > $expected
 	echo ".*inet_pton\+0x[[:xdigit:]]+[[:space:]]\($libc|inlined\)$" >> $expected
@@ -48,8 +55,8 @@ trace_libc_inet_pton_backtrace() {
 		;;
 	esac
 
-	perf_data=`mktemp -u /tmp/perf.data.XXX`
-	perf_script=`mktemp -u /tmp/perf.script.XXX`
+	perf_data=$(mktemp /tmp/perf.data.XXX) || return 1
+	perf_script=$(mktemp /tmp/perf.script.XXX) || return 1
 
 	# Check presence of libtraceevent support to run perf record
 	skip_no_probe_record_support "$event_name/$eventattr/"
@@ -59,9 +66,9 @@ trace_libc_inet_pton_backtrace() {
 	fi
 
 	perf record -e $event_name/$eventattr/ -o $perf_data ping -6 -c 1 ::1 > /dev/null 2>&1
-	# check if perf data file got created in above step.
-	if [ ! -e $perf_data ]; then
-		printf "FAIL: perf record failed to create \"%s\" \n" "$perf_data"
+	# mktemp created the file, so check that perf record wrote to it.
+	if [ ! -s "$perf_data" ]; then
+		printf "FAIL: perf record failed to write \"%s\" \n" "$perf_data"
 		return 1
 	fi
 	perf script -i $perf_data | tac | grep -m1 ^ping -B9 | tac > $perf_script
@@ -95,21 +102,59 @@ trace_libc_inet_pton_backtrace() {
 	# even if the perf script output does not match.
 }
 
+# The probes added, including any _1, _2... suffix perf probe appended.
+libc_inet_pton_events() {
+	perf probe -l 2>/dev/null | awk '{print $1}' |
+		grep -E "^probe_libc:inet_pton_$$(_[[:digit:]]+)?$"
+}
+
 delete_libc_inet_pton_event() {
+	# List rather than use event_name, which a signal may have left unset.
+	# Retry as, like adding, deleting can fail with EBUSY.
+	local attempts=0
+	local probe
+
+	while [ $attempts -lt 3 ]; do
+		for probe in $(libc_inet_pton_events); do
+			perf probe -q -d "$probe"
+		done
 
-	if [ -n "$event_name" ] ; then
-		perf probe -q -d $event_name
-	fi
+		if [ -z "$(libc_inet_pton_events)" ]; then
+			return 0
+		fi
+
+		attempts=$((attempts + 1))
+		sleep 0.1
+	done
+
+	printf "WARN: could not delete event(s): %s\n" \
+		"$(libc_inet_pton_events | tr '\n' ' ')"
+	return 1
+}
+
+cleanup() {
+	rm -f ${perf_data} ${perf_script} ${expected}
+	delete_libc_inet_pton_event
+
+	trap - EXIT TERM INT
+}
+
+trap_cleanup() {
+	cleanup
+	exit 1
 }
 
 # Check for IPv6 interface existence
 ip a sh lo | grep -F -q inet6 || exit 2
 [ "$(id -u)" = 0 ] || exit 2
 
+# After the skips, as trap_cleanup exits 1. A pid scoped probe is never reused,
+# so always remove it.
+trap trap_cleanup EXIT TERM INT
+
 skip_if_no_perf_probe && \
 add_libc_inet_pton_event && \
 trace_libc_inet_pton_backtrace
 err=$?
-rm -f ${perf_data} ${perf_script} ${expected}
-delete_libc_inet_pton_event
+cleanup
 exit $err
-- 
2.56.0.rc1.315.gc6ed9934b7-goog