Commit 04d23194 authored by Andrii Nakryiko's avatar Andrii Nakryiko
Browse files

Merge branch 'selftests/bpf: fix flaky send_signal test' 



Yonghong Song says:

====================

The bpf selftest send_signal() is flaky for its subtests trying to
send signals in softirq/nmi context. To reduce flakiness, the
signal-targetted process priority is boosted, which should minimize
preemption of that process and improve the possibility that
the underlying task in softirq/nmi context is the bpf_send_signal()
wanted task.

Patch #1 did a refactoring to use ASSERT_* instead of old CHECK macros.
Patch #2 did actual change of boosting priority.

Changelog:
  v1 -> v2:
    remove skip logic where the underlying task in interrupt context
    is not the intended one.
====================

Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
parents 87bb11cc b16ac5bf

tools/testing/selftests/bpf/prog_tests/send_signal.c

+36 −25
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

#include <test_progs.h>

#include <sys/time.h>

#include <sys/resource.h>

#include "test_send_signal_kern.skel.h"



int sigusr1_received = 0;
@@ -10,29 +12,25 @@ static void sigusr1_handler(int signum) 
}



static void test_send_signal_common(struct perf_event_attr *attr,

				    bool signal_thread,

				    const char *test_name)

				    bool signal_thread)

{

	struct test_send_signal_kern *skel;

	int pipe_c2p[2], pipe_p2c[2];

	int err = -1, pmu_fd = -1;

	__u32 duration = 0;

	char buf[256];

	pid_t pid;



	if (CHECK(pipe(pipe_c2p), test_name,

		  "pipe pipe_c2p error: %s\n", strerror(errno)))

	if (!ASSERT_OK(pipe(pipe_c2p), "pipe_c2p"))

		return;



	if (CHECK(pipe(pipe_p2c), test_name,

		  "pipe pipe_p2c error: %s\n", strerror(errno))) {

	if (!ASSERT_OK(pipe(pipe_p2c), "pipe_p2c")) {

		close(pipe_c2p[0]);

		close(pipe_c2p[1]);

		return;

	}



	pid = fork();

	if (CHECK(pid < 0, test_name, "fork error: %s\n", strerror(errno))) {

	if (!ASSERT_GE(pid, 0, "fork")) {

		close(pipe_c2p[0]);

		close(pipe_c2p[1]);

		close(pipe_p2c[0]);
@@ -41,26 +39,40 @@ static void test_send_signal_common(struct perf_event_attr *attr, 
	}



	if (pid == 0) {

		int old_prio;



		/* install signal handler and notify parent */

		signal(SIGUSR1, sigusr1_handler);



		close(pipe_c2p[0]); /* close read */

		close(pipe_p2c[1]); /* close write */



		/* boost with a high priority so we got a higher chance

		 * that if an interrupt happens, the underlying task

		 * is this process.

		 */

		errno = 0;

		old_prio = getpriority(PRIO_PROCESS, 0);

		ASSERT_OK(errno, "getpriority");

		ASSERT_OK(setpriority(PRIO_PROCESS, 0, -20), "setpriority");



		/* notify parent signal handler is installed */

		CHECK(write(pipe_c2p[1], buf, 1) != 1, "pipe_write", "err %d\n", -errno);

		ASSERT_EQ(write(pipe_c2p[1], buf, 1), 1, "pipe_write");



		/* make sure parent enabled bpf program to send_signal */

		CHECK(read(pipe_p2c[0], buf, 1) != 1, "pipe_read", "err %d\n", -errno);

		ASSERT_EQ(read(pipe_p2c[0], buf, 1), 1, "pipe_read");



		/* wait a little for signal handler */

		sleep(1);



		buf[0] = sigusr1_received ? '2' : '0';

		CHECK(write(pipe_c2p[1], buf, 1) != 1, "pipe_write", "err %d\n", -errno);

		ASSERT_EQ(write(pipe_c2p[1], buf, 1), 1, "pipe_write");



		/* wait for parent notification and exit */

		CHECK(read(pipe_p2c[0], buf, 1) != 1, "pipe_read", "err %d\n", -errno);

		ASSERT_EQ(read(pipe_p2c[0], buf, 1), 1, "pipe_read");



		/* restore the old priority */

		ASSERT_OK(setpriority(PRIO_PROCESS, 0, old_prio), "setpriority");



		close(pipe_c2p[1]);

		close(pipe_p2c[0]);
@@ -71,20 +83,19 @@ static void test_send_signal_common(struct perf_event_attr *attr, 
	close(pipe_p2c[0]); /* close read */



	skel = test_send_signal_kern__open_and_load();

	if (CHECK(!skel, "skel_open_and_load", "skeleton open_and_load failed\n"))

	if (!ASSERT_OK_PTR(skel, "skel_open_and_load"))

		goto skel_open_load_failure;



	if (!attr) {

		err = test_send_signal_kern__attach(skel);

		if (CHECK(err, "skel_attach", "skeleton attach failed\n")) {

		if (!ASSERT_OK(err, "skel_attach")) {

			err = -1;

			goto destroy_skel;

		}

	} else {

		pmu_fd = syscall(__NR_perf_event_open, attr, pid, -1,

				 -1 /* group id */, 0 /* flags */);

		if (CHECK(pmu_fd < 0, test_name, "perf_event_open error: %s\n",

			strerror(errno))) {

		if (!ASSERT_GE(pmu_fd, 0, "perf_event_open")) {

			err = -1;

			goto destroy_skel;

		}
@@ -96,7 +107,7 @@ static void test_send_signal_common(struct perf_event_attr *attr, 
	}



	/* wait until child signal handler installed */

	CHECK(read(pipe_c2p[0], buf, 1) != 1, "pipe_read", "err %d\n", -errno);

	ASSERT_EQ(read(pipe_c2p[0], buf, 1), 1, "pipe_read");



	/* trigger the bpf send_signal */

	skel->bss->pid = pid;
@@ -104,21 +115,21 @@ static void test_send_signal_common(struct perf_event_attr *attr, 
	skel->bss->signal_thread = signal_thread;



	/* notify child that bpf program can send_signal now */

	CHECK(write(pipe_p2c[1], buf, 1) != 1, "pipe_write", "err %d\n", -errno);

	ASSERT_EQ(write(pipe_p2c[1], buf, 1), 1, "pipe_write");



	/* wait for result */

	err = read(pipe_c2p[0], buf, 1);

	if (CHECK(err < 0, test_name, "reading pipe error: %s\n", strerror(errno)))

	if (!ASSERT_GE(err, 0, "reading pipe"))

		goto disable_pmu;

	if (CHECK(err == 0, test_name, "reading pipe error: size 0\n")) {

	if (!ASSERT_GT(err, 0, "reading pipe error: size 0")) {

		err = -1;

		goto disable_pmu;

	}



	CHECK(buf[0] != '2', test_name, "incorrect result\n");

	ASSERT_EQ(buf[0], '2', "incorrect result");



	/* notify child safe to exit */

	CHECK(write(pipe_p2c[1], buf, 1) != 1, "pipe_write", "err %d\n", -errno);

	ASSERT_EQ(write(pipe_p2c[1], buf, 1), 1, "pipe_write");



disable_pmu:

	close(pmu_fd);
@@ -132,7 +143,7 @@ static void test_send_signal_common(struct perf_event_attr *attr, 


static void test_send_signal_tracepoint(bool signal_thread)

{

	test_send_signal_common(NULL, signal_thread, "tracepoint");

	test_send_signal_common(NULL, signal_thread);

}



static void test_send_signal_perf(bool signal_thread)
@@ -143,7 +154,7 @@ static void test_send_signal_perf(bool signal_thread) 
		.config = PERF_COUNT_SW_CPU_CLOCK,

	};



	test_send_signal_common(&attr, signal_thread, "perf_sw_event");

	test_send_signal_common(&attr, signal_thread);

}



static void test_send_signal_nmi(bool signal_thread)
@@ -172,7 +183,7 @@ static void test_send_signal_nmi(bool signal_thread) 
		close(pmu_fd);

	}



	test_send_signal_common(&attr, signal_thread, "perf_hw_event");

	test_send_signal_common(&attr, signal_thread);

}



void test_send_signal(void)