This signal handler loops over all tests on ctrl-C, but it's active
while the test list is being constructed. process.pid is 0, then -1,
then finally set to the child pid on fork. If the Ctrl-C is received
during this point a kill(-1, SIGINT) can be sent which affects all
processes.

Make sure the child has forked first before forwarding the signal. This
can be reproduced with ctrl-C immediately after launching perf test
which terminates the ssh connection.

Fixes: 553d5efeb341 ("perf test: Add a signal handler to kill forked child processes")
Signed-off-by: James Clark <james.clark@linaro.org>
---
 tools/perf/tests/builtin-test.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/tests/builtin-test.c b/tools/perf/tests/builtin-test.c
index 8dcf74d3c0a3..4751dd3c6f67 100644
--- a/tools/perf/tests/builtin-test.c
+++ b/tools/perf/tests/builtin-test.c
@@ -508,7 +508,7 @@ static int __cmd_test(struct test_suite **suites, int argc, const char *argv[],
 		for (size_t x = 0; x < num_tests; x++) {
 			struct child_test *child_test = child_tests[x];
 
-			if (!child_test)
+			if (!child_test || child_test->process.pid <= 0)
 				continue;
 
 			pr_debug3("Killing %d pid %d\n",
-- 
2.34.1

On Fri, 29 Nov 2024 15:19:48 +0000, James Clark wrote:

> This signal handler loops over all tests on ctrl-C, but it's active
> while the test list is being constructed. process.pid is 0, then -1,
> then finally set to the child pid on fork. If the Ctrl-C is received
> during this point a kill(-1, SIGINT) can be sent which affects all
> processes.
> 
> Make sure the child has forked first before forwarding the signal. This
> can be reproduced with ctrl-C immediately after launching perf test
> which terminates the ssh connection.
> 
> [...]

Applied to perf-tools, thanks!

Best regards,
Namhyung

On Fri, Nov 29, 2024 at 7:20 AM James Clark <james.clark@linaro.org> wrote:
>
> This signal handler loops over all tests on ctrl-C, but it's active
> while the test list is being constructed. process.pid is 0, then -1,
> then finally set to the child pid on fork. If the Ctrl-C is received
> during this point a kill(-1, SIGINT) can be sent which affects all
> processes.
>
> Make sure the child has forked first before forwarding the signal. This
> can be reproduced with ctrl-C immediately after launching perf test
> which terminates the ssh connection.
>
> Fixes: 553d5efeb341 ("perf test: Add a signal handler to kill forked child processes")
> Signed-off-by: James Clark <james.clark@linaro.org>

(Resend as plain text)

Reviewed-by: Ian Rogers <irogers@google.com>

Sorry for the lost ssh connections :-)

Thanks,
Ian

>
> ---
>  tools/perf/tests/builtin-test.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/perf/tests/builtin-test.c b/tools/perf/tests/builtin-test.c
> index 8dcf74d3c0a3..4751dd3c6f67 100644
> --- a/tools/perf/tests/builtin-test.c
> +++ b/tools/perf/tests/builtin-test.c
> @@ -508,7 +508,7 @@ static int __cmd_test(struct test_suite **suites, int argc, const char *argv[],
>                 for (size_t x = 0; x < num_tests; x++) {
>                         struct child_test *child_test = child_tests[x];
>
> -                       if (!child_test)
> +                       if (!child_test || child_test->process.pid <= 0)
>                                 continue;
>
>                         pr_debug3("Killing %d pid %d\n",
> --
> 2.34.1
>