From 6f6cc426451bb15a85896efc7c85665b59af04ae Mon Sep 17 00:00:00 2001 From: Yonghong Song Date: Tue, 17 Aug 2021 12:09:18 -0700 Subject: [PATCH 1/2] selftests/bpf: Replace CHECK with ASSERT_* macros in send_signal.c Replace CHECK in send_signal.c with ASSERT_* macros as ASSERT_* macros are generally preferred. There is no funcitonality change. Signed-off-by: Yonghong Song Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20210817190918.3186400-1-yhs@fb.com --- .../selftests/bpf/prog_tests/send_signal.c | 45 +++++++++---------- 1 file changed, 20 insertions(+), 25 deletions(-) diff --git a/tools/testing/selftests/bpf/prog_tests/send_signal.c b/tools/testing/selftests/bpf/prog_tests/send_signal.c index 023cc532992d..41e158ae888e 100644 --- a/tools/testing/selftests/bpf/prog_tests/send_signal.c +++ b/tools/testing/selftests/bpf/prog_tests/send_signal.c @@ -10,29 +10,25 @@ 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]); @@ -48,19 +44,19 @@ static void test_send_signal_common(struct perf_event_attr *attr, close(pipe_p2c[1]); /* close write */ /* 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"); close(pipe_c2p[1]); close(pipe_p2c[0]); @@ -71,20 +67,19 @@ 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 +91,7 @@ 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 +99,21 @@ 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 +127,7 @@ 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 +138,7 @@ 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 +167,7 @@ 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) From b16ac5bf732a5e23d164cf908ec7742d6a6120d3 Mon Sep 17 00:00:00 2001 From: Yonghong Song Date: Tue, 17 Aug 2021 12:09:23 -0700 Subject: [PATCH 2/2] selftests/bpf: Fix flaky send_signal test libbpf CI has reported send_signal test is flaky although I am not able to reproduce it in my local environment. But I am able to reproduce with on-demand libbpf CI ([1]). Through code analysis, the following is possible reason. The failed subtest runs bpf program in softirq environment. Since bpf_send_signal() only sends to a fork of "test_progs" process. If the underlying current task is not "test_progs", bpf_send_signal() will not be triggered and the subtest will fail. To reduce the chances where the underlying process is not the intended one, this patch boosted scheduling priority to -20 (highest allowed by setpriority() call). And I did 10 runs with on-demand libbpf CI with this patch and I didn't observe any failures. [1] https://github.com/libbpf/libbpf/actions/workflows/ondemand.yml Signed-off-by: Yonghong Song Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20210817190923.3186725-1-yhs@fb.com --- .../selftests/bpf/prog_tests/send_signal.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/tools/testing/selftests/bpf/prog_tests/send_signal.c b/tools/testing/selftests/bpf/prog_tests/send_signal.c index 41e158ae888e..776916b61c40 100644 --- a/tools/testing/selftests/bpf/prog_tests/send_signal.c +++ b/tools/testing/selftests/bpf/prog_tests/send_signal.c @@ -1,5 +1,7 @@ // SPDX-License-Identifier: GPL-2.0 #include +#include +#include #include "test_send_signal_kern.skel.h" int sigusr1_received = 0; @@ -37,12 +39,23 @@ 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 */ ASSERT_EQ(write(pipe_c2p[1], buf, 1), 1, "pipe_write"); @@ -58,6 +71,9 @@ static void test_send_signal_common(struct perf_event_attr *attr, /* wait for parent notification and exit */ 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]); exit(0);