[PATCH v1] perf test: Fix inet_pton probe failure due to multiple probes

[PATCH v1] perf test: Fix inet_pton probe failure due to multiple probes

[Ian Rogers]

When adding a probe for libc's inet_pton, perf probe may create multiple
probe points (e.g., due to inlining or multiple symbol resolutions),
resulting in multiple identical event names being output (e.g.,
`probe_libc:inet_pton_1`).

The script previously used a brittle pipeline (`tail -n +2 | head -n -5`)
and an awk script to extract the event name. When multiple probes were
added, awk would output the event name multiple times, which expanded
to multiple words in bash. This broke the subsequent `perf record` and
`perf probe -d` commands, causing the test to fail with:
`Error: another command except --add is set.`

Fix this by removing the brittle `tail/head` commands and appending
`| sort -u` to the awk extraction. This ensures that only a single,
unique event name is captured, regardless of how many probe points
are created.

Assisted-by: Gemini:gemini-3.1-pro-preview
Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/tests/shell/record+probe_libc_inet_pton.sh | 4 ++--
 1 file changed, 2 insertions(+), 2 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 ab99bef556bf..b717063f70c2 100755
--- a/tools/perf/tests/shell/record+probe_libc_inet_pton.sh
+++ b/tools/perf/tests/shell/record+probe_libc_inet_pton.sh
@@ -22,9 +22,9 @@ event_pattern='probe_libc:inet_pton(_[[:digit:]]+)?'
 
 add_libc_inet_pton_event() {
 
-	event_name=$(perf probe -f -x $libc -a inet_pton 2>&1 | tail -n +2 | head -n -5 | \
+	event_name=$(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}')
+			("\\(on inet_pton in " l "\\)") {print $1}' | sort -u)
 
 	if [ $? -ne 0 ] || [ -z "$event_name" ] ; then
 		printf "FAIL: could not add event\n"
-- 
2.53.0.1213.gd9a14994de-goog

Re: [PATCH v1] perf test: Fix inet_pton probe failure due to multiple probes

[sashiko-bot]

Sashiko AI review found 1 potential issue(s):
- [Medium] The use of `sort -u` fails to guarantee a single event name on systems without uprobe multiprobe support, leaving the test broken in those environments.
--

commit 82ddf08abe58056272425532334245db796f2020
Author: Ian Rogers <irogers@google.com>

perf test: Fix inet_pton probe failure due to multiple probes

This commit attempts to fix a test failure caused by perf probe outputting
multiple probe points. It replaces a tail/head pipeline with sort -u to try
and extract a single, unique event name from the awk script output.

> 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 ab99bef556bf0..b717063f70c27 100755
> --- a/tools/perf/tests/shell/record+probe_libc_inet_pton.sh
> +++ b/tools/perf/tests/shell/record+probe_libc_inet_pton.sh
> @@ -22,9 +22,9 @@ event_pattern='probe_libc:inet_pton(_[[:digit:]]+)?'
>  
>  add_libc_inet_pton_event() {
>  
> -	event_name=$(perf probe -f -x $libc -a inet_pton 2>&1 | tail -n +2 | head -n -5 | \
> +	event_name=$(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}')
> +			("\\(on inet_pton in " l "\\)") {print $1}' | sort -u)

Does sort -u guarantee a single event name is captured on kernels without
uprobe multiprobe support?

On systems without multiprobe support, perf probe actively prevents name
collisions by appending indices to subsequent probe points, outputting
names like probe_libc:inet_pton and probe_libc:inet_pton_1. 

Because these strings are textually distinct, sort -u will output all of
them rather than deduplicating them.

This leaves the event_name variable containing multiple words separated by
newlines. When expanded unquoted in the subsequent perf record and perf probe
commands, bash word splitting causes the same syntax errors the patch intends
to fix.

Could this use head -n 1 or awk '{print $1; exit}' instead to robustly
guarantee a single name is captured across all environments?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260410002351.10856-1-irogers@google.com?part=1