perf test: Add a signal handler to kill forked child processes

If the `perf test` process is killed the child tests continue running
and may run indefinitely. Propagate SIGINT (ctrl-C) and SIGTERM (kill)
signals to the running child processes so that they terminate when the
parent is killed.

Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Colin Ian King <colin.i.king@gmail.com>
Cc: Howard Chu <howardchu95@gmail.com>
Cc: Weilin Wang <weilin.wang@intel.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Ilya Leoshkevich <iii@linux.ibm.com>
Cc: Thomas Richter <tmricht@linux.ibm.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Dapeng Mi <dapeng1.mi@linux.intel.com>
Cc: Athira Jajeev <atrajeev@linux.vnet.ibm.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Veronika Molnarova <vmolnaro@redhat.com>
Link: https://lore.kernel.org/r/20241025192109.132482-10-irogers@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

tools/perf/tests/builtin-test.c

@@ -472,13 +472,22 @@ static int start_test(struct test_suite *test, int i, int subi, struct child_tes
 	for (j = 0, k = 0; j < ARRAY_SIZE(tests); j++, k = 0)	\
 		while ((t = tests[j][k++]) != NULL)
 
+/* State outside of __cmd_test for the sake of the signal handler. */
+
+static size_t num_tests;
+static struct child_test **child_tests;
+static jmp_buf cmd_test_jmp_buf;
+
+static void cmd_test_sig_handler(int sig)
+{
+	siglongjmp(cmd_test_jmp_buf, sig);
+}
+
 static int __cmd_test(int argc, const char *argv[], struct intlist *skiplist)
 {
 	struct test_suite *t;
-	int width = 0;
+	static int width = 0;
 	unsigned int j, k;
-	size_t num_tests = 0;
-	struct child_test **child_tests;
 	int err = 0;
 
 	for_each_test(j, k, t) {
@@ -502,6 +511,26 @@ static int __cmd_test(int argc, const char *argv[], struct intlist *skiplist)
 	if (!child_tests)
 		return -ENOMEM;
 
+	err = sigsetjmp(cmd_test_jmp_buf, 1);
+	if (err) {
+		pr_err("\nSignal (%d) while running tests.\nTerminating tests with the same signal\n",
+		       err);
+		for (size_t x = 0; x < num_tests; x++) {
+			struct child_test *child_test = child_tests[x];
+
+			if (!child_test)
+				continue;
+
+			pr_debug3("Killing %d pid %d\n",
+				  child_test->test_num + 1,
+				  child_test->process.pid);
+			kill(child_test->process.pid, err);
+		}
+		goto err_out;
+	}
+	signal(SIGINT, cmd_test_sig_handler);
+	signal(SIGTERM, cmd_test_sig_handler);
+
 	/*
 	 * In parallel mode pass 1 runs non-exclusive tests in parallel, pass 2
 	 * runs the exclusive tests sequentially. In other modes all tests are
@@ -562,6 +591,8 @@ static int __cmd_test(int argc, const char *argv[], struct intlist *skiplist)
 		}
 	}
 err_out:
+	signal(SIGINT, SIG_DFL);
+	signal(SIGTERM, SIG_DFL);
 	if (err) {
 		pr_err("Internal test harness failure. Completing any started tests:\n:");
 		for (size_t x = 0; x < num_tests; x++)