[PATCH 2/2] perf test: Test FASYNC with watermark wakeups.

[Kyle Huey <me@kylehuey.com>]

The test uses PERF_RECORD_SWITCH records to fill the ring buffer and
trigger the watermark wakeup, which in turn should trigger an IO
signal.

Signed-off-by: Kyle Huey <khuey@kylehuey.com>
---
 tools/perf/tests/Build              |   1 +
 tools/perf/tests/builtin-test.c     |   1 +
 tools/perf/tests/tests.h            |   1 +
 tools/perf/tests/watermark_signal.c | 123 ++++++++++++++++++++++++++++
 4 files changed, 126 insertions(+)
 create mode 100644 tools/perf/tests/watermark_signal.c

diff --git a/tools/perf/tests/Build b/tools/perf/tests/Build
index 53ba9c3e20e0..de43eb60b280 100644
--- a/tools/perf/tests/Build
+++ b/tools/perf/tests/Build
@@ -67,6 +67,7 @@ perf-y += sigtrap.o
 perf-y += event_groups.o
 perf-y += symbols.o
 perf-y += util.o
+perf-y += watermark_signal.o
 
 ifeq ($(SRCARCH),$(filter $(SRCARCH),x86 arm arm64 powerpc))
 perf-$(CONFIG_DWARF_UNWIND) += dwarf-unwind.o
diff --git a/tools/perf/tests/builtin-test.c b/tools/perf/tests/builtin-test.c
index 4a5973f9bb9b..715c01a2172a 100644
--- a/tools/perf/tests/builtin-test.c
+++ b/tools/perf/tests/builtin-test.c
@@ -124,6 +124,7 @@ static struct test_suite *generic_tests[] = {
 	&suite__event_groups,
 	&suite__symbols,
 	&suite__util,
+	&suite__watermark_signal,
 	NULL,
 };
 
diff --git a/tools/perf/tests/tests.h b/tools/perf/tests/tests.h
index dad3d7414142..7ef4e0d0a77b 100644
--- a/tools/perf/tests/tests.h
+++ b/tools/perf/tests/tests.h
@@ -146,6 +146,7 @@ DECLARE_SUITE(sigtrap);
 DECLARE_SUITE(event_groups);
 DECLARE_SUITE(symbols);
 DECLARE_SUITE(util);
+DECLARE_SUITE(watermark_signal);
 
 /*
  * PowerPC and S390 do not support creation of instruction breakpoints using the
diff --git a/tools/perf/tests/watermark_signal.c b/tools/perf/tests/watermark_signal.c
new file mode 100644
index 000000000000..ae4abedc4b7c
--- /dev/null
+++ b/tools/perf/tests/watermark_signal.c
@@ -0,0 +1,123 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <stddef.h>
+#include <signal.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include <errno.h>
+#include <fcntl.h>
+
+#include "tests.h"
+#include "debug.h"
+#include "event.h"
+#include "../perf-sys.h"
+#include "cloexec.h"
+#include <internal/lib.h> // page_size
+
+static int sigio_count;
+
+static void handle_sigio(int sig __always_unused)
+{
+	++sigio_count;
+}
+
+static void do_child(void)
+{
+	for (int i = 0; i < 20; ++i)
+		sleep(1);
+
+	exit(0);
+}
+
+static int test__watermark_signal(struct test_suite *test __maybe_unused, int subtest __maybe_unused)
+{
+	struct perf_event_attr attr;
+	struct perf_event_mmap_page *p = NULL;
+	sighandler_t previous_sigio = SIG_ERR;
+	pid_t child = -1;
+	int fd = -1;
+	int ret = TEST_FAIL;
+
+	previous_sigio = signal(SIGIO, handle_sigio);
+	if (previous_sigio == SIG_ERR) {
+		pr_debug("failed setting SIGIO handler\n");
+		goto cleanup;
+	}
+
+	memset(&attr, 0, sizeof(attr));
+	attr.size = sizeof(attr);
+	attr.type = PERF_TYPE_SOFTWARE;
+	attr.config = PERF_COUNT_SW_DUMMY;
+	attr.sample_period = 1;
+	attr.disabled = 1;
+	attr.watermark = 1;
+	attr.context_switch = 1;
+	attr.wakeup_watermark = 1;
+
+	child = fork();
+	if (child == 0)
+		do_child();
+	else if (child < 0) {
+		pr_debug("failed fork() %d\n", errno);
+		goto cleanup;
+	}
+
+	fd = sys_perf_event_open(&attr, child, -1, -1,
+				 perf_event_open_cloexec_flag());
+	if (fd < 0) {
+		pr_debug("failed opening event %llx\n", attr.config);
+		goto cleanup;
+	}
+
+	if (fcntl(fd, F_SETFL, FASYNC)) {
+		pr_debug("failed F_SETFL FASYNC %d\n", errno);
+		goto cleanup;
+	}
+
+	if (fcntl(fd, F_SETOWN, getpid())) {
+		pr_debug("failed F_SETOWN getpid() %d\n", errno);
+		goto cleanup;
+	}
+
+	if (fcntl(fd, F_SETSIG, SIGIO)) {
+		pr_debug("failed F_SETSIG SIGIO %d\n", errno);
+		goto cleanup;
+	}
+
+	p = mmap(NULL, 2 * page_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+	if (p == NULL) {
+		pr_debug("failed to mmap\n");
+		goto cleanup;
+	}
+
+	if (ioctl(fd, PERF_EVENT_IOC_ENABLE, 0)) {
+		pr_debug("failed PERF_EVENT_IOC_ENABLE %d\n", errno);
+		goto cleanup;
+	}
+
+	sleep(30);
+
+	ret = (sigio_count == 1) ? TEST_OK : TEST_FAIL;
+
+cleanup:
+	if (p != NULL)
+		munmap(p, 2 * page_size);
+
+	if (fd >= 0)
+		close(fd);
+
+	if (child > 0) {
+		kill(child, SIGTERM);
+		waitpid(child, NULL, 0);
+	}
+
+	if (previous_sigio != SIG_ERR)
+		signal(SIGIO, previous_sigio);
+
+	return ret;
+}
+
+DEFINE_SUITE("Watermark signal handler", watermark_signal);
-- 
2.34.1