On Fri, 2024-11-01 at 14:18 +0100, Kumar Kartikeya Dwivedi wrote: [...] > I see that all selftests except one passed. The one that didn't > appears to have been cancelled after running for an hour, and stalled > after select_reuseport:OK. > Looking at the LLVM 18 > (https://github.com/kernel-patches/bpf/actions/runs/11621768944/job/32366412581?pr=7999) > run instead of LLVM 17 > (https://github.com/kernel-patches/bpf/actions/runs/11621768944/job/32366400714?pr=7999, > which failed), it seems the next test send_signal_tracepoint. > > Is this known to be flaky? I'm guessing not and it is probably caused > by my patch, but just want to confirm before I begin debugging. I suspect this is a test send_signal. It started to hang for me yesterday w/o any apparent reason (on master branch). I added workaround to avoid stalls, but this does not address the issue with the test. Workaround follows. --- diff --git a/tools/testing/selftests/bpf/prog_tests/send_signal.c b/tools/testing/selftests/bpf/prog_tests/send_signal.c index ee5a221b4103..4af127945417 100644 --- a/tools/testing/selftests/bpf/prog_tests/send_signal.c +++ b/tools/testing/selftests/bpf/prog_tests/send_signal.c @@ -18,6 +18,38 @@ static void sigusr1_siginfo_handler(int s, siginfo_t *i, void *v) static char log_buf[64 * 1024]; +static ssize_t read_with_timeout(int fd, void *buf, size_t count) +{ + struct timeval tv = { 1, 0 }; + fd_set fds; + int err; + + FD_ZERO(&fds); + FD_SET(fd, &fds); + err = select(fd + 1, &fds, NULL, NULL, &tv); + if (!ASSERT_GE(err, 0, "read select")) + return err; + if (FD_ISSET(fd, &fds)) + return read(fd, buf, count); + return -EAGAIN; +} + +static ssize_t write_with_timeout(int fd, void *buf, size_t count) +{ + struct timeval tv = { 1, 0 }; + fd_set fds; + int err; + + FD_ZERO(&fds); + FD_SET(fd, &fds); + err = select(fd + 1, NULL, &fds, NULL, &tv); + if (!ASSERT_GE(err, 0, "write select")) + return err; + if (FD_ISSET(fd, &fds)) + return write(fd, buf, count); + return -EAGAIN; +} + static void test_send_signal_common(struct perf_event_attr *attr, bool signal_thread, bool remote) { @@ -75,10 +107,10 @@ static void test_send_signal_common(struct perf_event_attr *attr, } /* notify parent signal handler is installed */ - ASSERT_EQ(write(pipe_c2p[1], buf, 1), 1, "pipe_write"); + ASSERT_EQ(write_with_timeout(pipe_c2p[1], buf, 1), 1, "pipe_write"); /* make sure parent enabled bpf program to send_signal */ - ASSERT_EQ(read(pipe_p2c[0], buf, 1), 1, "pipe_read"); + ASSERT_EQ(read_with_timeout(pipe_p2c[0], buf, 1), 1, "pipe_read"); /* wait a little for signal handler */ for (int i = 0; i < 1000000000 && !sigusr1_received; i++) { @@ -94,10 +126,10 @@ static void test_send_signal_common(struct perf_event_attr *attr, buf[0] = sigusr1_received; ASSERT_EQ(sigusr1_received, 8, "sigusr1_received"); - ASSERT_EQ(write(pipe_c2p[1], buf, 1), 1, "pipe_write"); + ASSERT_EQ(write_with_timeout(pipe_c2p[1], buf, 1), 1, "pipe_write"); /* wait for parent notification and exit */ - ASSERT_EQ(read(pipe_p2c[0], buf, 1), 1, "pipe_read"); + ASSERT_EQ(read_with_timeout(pipe_p2c[0], buf, 1), 1, "pipe_read"); /* restore the old priority */ if (!remote) @@ -158,7 +190,7 @@ static void test_send_signal_common(struct perf_event_attr *attr, } /* wait until child signal handler installed */ - ASSERT_EQ(read(pipe_c2p[0], buf, 1), 1, "pipe_read"); + ASSERT_EQ(read_with_timeout(pipe_c2p[0], buf, 1), 1, "pipe_read"); /* trigger the bpf send_signal */ skel->bss->signal_thread = signal_thread; @@ -172,7 +204,7 @@ static void test_send_signal_common(struct perf_event_attr *attr, } /* notify child that bpf program can send_signal now */ - ASSERT_EQ(write(pipe_p2c[1], buf, 1), 1, "pipe_write"); + ASSERT_EQ(write_with_timeout(pipe_p2c[1], buf, 1), 1, "pipe_write"); /* For the remote test, the BPF program is triggered from this * process but the other process/thread is signaled. @@ -188,7 +220,7 @@ static void test_send_signal_common(struct perf_event_attr *attr, } /* wait for result */ - err = read(pipe_c2p[0], buf, 1); + err = read_with_timeout(pipe_c2p[0], buf, 1); if (!ASSERT_GE(err, 0, "reading pipe")) goto disable_pmu; if (!ASSERT_GT(err, 0, "reading pipe error: size 0")) { @@ -199,7 +231,7 @@ static void test_send_signal_common(struct perf_event_attr *attr, ASSERT_EQ(buf[0], 8, "incorrect result"); /* notify child safe to exit */ - ASSERT_EQ(write(pipe_p2c[1], buf, 1), 1, "pipe_write"); + ASSERT_EQ(write_with_timeout(pipe_p2c[1], buf, 1), 1, "pipe_write"); disable_pmu: close(pmu_fd);
