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

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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: Andrii Nakryiko <andrii@kernel.org>
This commit is contained in:
Andrii Nakryiko 2021-08-17 14:08:31 -07:00
commit 04d2319467
1 changed files with 36 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

61
tools/testing/selftests/bpf/prog_tests/send_signal.c
View File

@ -1,5 +1,7 @@
// 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 @@ skel_open_load_failure:
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)