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4a54de65 |
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09-Mar-2023 |
David Vernet <void@manifault.com> |
bpf/selftests: Fix send_signal tracepoint tests The send_signal tracepoint tests are non-deterministically failing in CI. The test works as follows: 1. Two pairs of file descriptors are created using the pipe() function. One pair is used to communicate between a parent process -> child process, and the other for the reverse direction. 2. A child is fork()'ed. The child process registers a signal handler, notifies its parent that the signal handler is registered, and then and waits for its parent to have enabled a BPF program that sends a signal. 3. The parent opens and loads a BPF skeleton with programs that send signals to the child process. The different programs are triggered by different perf events (either NMI or normal perf), or by regular tracepoints. The signal is delivered to the child whenever the child triggers the program. 4. The child's signal handler is invoked, which sets a flag saying that the signal handler was reached. The child then signals to the parent that it received the signal, and the test ends. The perf testcases (send_signal_perf{_thread} and send_signal_nmi{_thread}) work 100% of the time, but the tracepoint testcases fail non-deterministically because the tracepoint is not always being fired for the child. There are two tracepoint programs registered in the test: 'tracepoint/sched/sched_switch', and 'tracepoint/syscalls/sys_enter_nanosleep'. The child never intentionally blocks, nor sleeps, so neither tracepoint is guaranteed to be triggered. To fix this, we can have the child trigger the nanosleep program with a usleep(). Before this patch, the test would fail locally every 2-3 runs. Now, it doesn't fail after more than 1000 runs. Signed-off-by: David Vernet <void@manifault.com> Link: https://lore.kernel.org/r/20230310061909.1420887-1-void@manifault.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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639de43e |
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27-Jul-2022 |
Daniel Müller <deso@posteo.net> |
selftests/bpf: Bump internal send_signal/send_signal_tracepoint timeout The send_signal/send_signal_tracepoint is pretty flaky, with at least one failure in every ten runs on a few attempts I've tried it: > test_send_signal_common:PASS:pipe_c2p 0 nsec > test_send_signal_common:PASS:pipe_p2c 0 nsec > test_send_signal_common:PASS:fork 0 nsec > test_send_signal_common:PASS:skel_open_and_load 0 nsec > test_send_signal_common:PASS:skel_attach 0 nsec > test_send_signal_common:PASS:pipe_read 0 nsec > test_send_signal_common:PASS:pipe_write 0 nsec > test_send_signal_common:PASS:reading pipe 0 nsec > test_send_signal_common:PASS:reading pipe error: size 0 0 nsec > test_send_signal_common:FAIL:incorrect result unexpected incorrect result: actual 48 != expected 50 > test_send_signal_common:PASS:pipe_write 0 nsec > #139/1 send_signal/send_signal_tracepoint:FAIL The reason does not appear to be a correctness issue in the strict sense. Rather, we merely do not receive the signal we are waiting for within the provided timeout. Let's bump the timeout by a factor of ten. With that change I have not been able to reproduce the failure in 150+ iterations. I am also sneaking in a small simplification to the test_progs test selection logic. Signed-off-by: Daniel Müller <deso@posteo.net> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Jiri Olsa <jolsa@kernel.org> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20220727182955.4044988-1-deso@posteo.net
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d3b351f6 |
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10-Mar-2022 |
Yonghong Song <yhs@fb.com> |
selftests/bpf: Fix a clang compilation error for send_signal.c Building selftests/bpf with latest clang compiler (clang15 built from source), I hit the following compilation error: /.../prog_tests/send_signal.c:43:16: error: variable 'j' set but not used [-Werror,-Wunused-but-set-variable] volatile int j = 0; ^ 1 error generated. The problem also exists with clang13 and clang14. clang12 is okay. In send_signal.c, we have the following code ... volatile int j = 0; [...] for (int i = 0; i < 100000000 && !sigusr1_received; i++) j /= i + 1; ... to burn CPU cycles so bpf_send_signal() helper can be tested in NMI mode. Slightly changing 'j /= i + 1' to 'j /= i + j + 1' or 'j++' can fix the problem. Further investigation indicated this should be a clang bug ([1]). The upstream fix will be proposed later. But it is a good idea to workaround the issue to unblock people who build kernel/selftests with clang. [1] https://discourse.llvm.org/t/strange-clang-unused-but-set-variable-error-with-volatile-variables/60841 Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20220311003721.2177170-1-yhs@fb.com
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1fd49864 |
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08-Mar-2022 |
Mykola Lysenko <mykolal@fb.com> |
Improve send_signal BPF test stability Substitute sleep with dummy CPU intensive computation. Finish aforemention computation as soon as signal was delivered to the test process. Make the BPF code to only execute when PID global variable is set Signed-off-by: Mykola Lysenko <mykolal@fb.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20220308200449.1757478-3-mykolal@fb.com
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b16ac5bf |
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17-Aug-2021 |
Yonghong Song <yhs@fb.com> |
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 <yhs@fb.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210817190923.3186725-1-yhs@fb.com
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6f6cc426 |
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17-Aug-2021 |
Yonghong Song <yhs@fb.com> |
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 <yhs@fb.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210817190918.3186400-1-yhs@fb.com
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bad2e478 |
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24-May-2021 |
Andrii Nakryiko <andrii@kernel.org> |
selftests/bpf: Turn on libbpf 1.0 mode and fix all IS_ERR checks Turn ony libbpf 1.0 mode. Fix all the explicit IS_ERR checks that now will be broken because libbpf returns NULL on error (and sets errno). Fix ASSERT_OK_PTR and ASSERT_ERR_PTR to work for both old mode and new modes and use them throughout selftests. This is trivial to do by using libbpf_get_error() API that all libbpf users are supposed to use, instead of IS_ERR checks. A bunch of checks also did explicit -1 comparison for various fd-returning APIs. Such checks are replaced with >= 0 or < 0 cases. There were also few misuses of bpf_object__find_map_by_name() in test_maps. Those are fixed in this patch as well. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com> Link: https://lore.kernel.org/bpf/20210525035935.1461796-3-andrii@kernel.org
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256eab48 |
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06-May-2021 |
Andrii Nakryiko <andrii@kernel.org> |
selftests/bpf: Stop using static variables for passing data to/from user-space In preparation of skipping emitting static variables in BPF skeletons, switch all current selftests uses of static variables to pass data between BPF and user-space to use global variables. All non-read-only `static volatile` variables become just plain global variables by dropping `static volatile` part. Read-only `static volatile const` variables, though, still require `volatile` modifier, otherwise compiler will ignore whatever values are set from user-space. Few static linker tests are using name-conflicting static variables to validate that static linker still properly handles static variables and doesn't trip up on name conflicts. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20210507054119.270888-4-andrii@kernel.org
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929e54a9 |
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06-Aug-2020 |
Jianlin Lv <Jianlin.Lv@arm.com> |
bpf: Fix compilation warning of selftests Clang compiler version: 12.0.0 The following warning appears during the selftests/bpf compilation: prog_tests/send_signal.c:51:3: warning: ignoring return value of ‘write’, declared with attribute warn_unused_result [-Wunused-result] 51 | write(pipe_c2p[1], buf, 1); | ^~~~~~~~~~~~~~~~~~~~~~~~~~ prog_tests/send_signal.c:54:3: warning: ignoring return value of ‘read’, declared with attribute warn_unused_result [-Wunused-result] 54 | read(pipe_p2c[0], buf, 1); | ^~~~~~~~~~~~~~~~~~~~~~~~~ ...... prog_tests/stacktrace_build_id_nmi.c:13:2: warning: ignoring return value of ‘fscanf’,declared with attribute warn_unused_result [-Wunused-resul] 13 | fscanf(f, "%llu", &sample_freq); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ test_tcpnotify_user.c:133:2: warning:ignoring return value of ‘system’, declared with attribute warn_unused_result [-Wunused-result] 133 | system(test_script); | ^~~~~~~~~~~~~~~~~~~ test_tcpnotify_user.c:138:2: warning:ignoring return value of ‘system’, declared with attribute warn_unused_result [-Wunused-result] 138 | system(test_script); | ^~~~~~~~~~~~~~~~~~~ test_tcpnotify_user.c:143:2: warning:ignoring return value of ‘system’, declared with attribute warn_unused_result [-Wunused-result] 143 | system(test_script); | ^~~~~~~~~~~~~~~~~~~ Add code that fix compilation warning about ignoring return value and handles any errors; Check return value of library`s API make the code more secure. Signed-off-by: Jianlin Lv <Jianlin.Lv@arm.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200806104224.95306-1-Jianlin.Lv@arm.com
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35697c12 |
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16-Jan-2020 |
Yonghong Song <yhs@fb.com> |
selftests/bpf: Fix test_progs send_signal flakiness with nmi mode Alexei observed that test_progs send_signal may fail if run with command line "./test_progs" and the tests will pass if just run "./test_progs -n 40". I observed similar issue with nmi subtest failure and added a delay 100 us in Commit ab8b7f0cb358 ("tools/bpf: Add self tests for bpf_send_signal_thread()") and the problem is gone for me. But the issue still exists in Alexei's testing environment. The current code uses sample_freq = 50 (50 events/second), which may not be enough. But if the sample_freq value is larger than sysctl kernel/perf_event_max_sample_rate, the perf_event_open syscall will fail. This patch changed nmi perf testing to use sample_period = 1, which means trying to sampling every event. This seems fixing the issue. Fixes: ab8b7f0cb358 ("tools/bpf: Add self tests for bpf_send_signal_thread()") Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200116174004.1522812-1-yhs@fb.com
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ab8b7f0c |
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14-Jan-2020 |
Yonghong Song <yhs@fb.com> |
tools/bpf: Add self tests for bpf_send_signal_thread() The test_progs send_signal() is amended to test bpf_send_signal_thread() as well. $ ./test_progs -n 40 #40/1 send_signal_tracepoint:OK #40/2 send_signal_perf:OK #40/3 send_signal_nmi:OK #40/4 send_signal_tracepoint_thread:OK #40/5 send_signal_perf_thread:OK #40/6 send_signal_nmi_thread:OK #40 send_signal:OK Summary: 1/6 PASSED, 0 SKIPPED, 0 FAILED Also took this opportunity to rewrite the send_signal test using skeleton framework and array mmap to make code simpler and more readable. Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200115035003.602425-1-yhs@fb.com
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86ccc384 |
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21-Aug-2019 |
Stanislav Fomichev <sdf@google.com> |
selftests/bpf: test_progs: remove unused ret send_signal test returns static codes from the subtests which nobody looks at, let's rely on the CHECK macros instead. Signed-off-by: Stanislav Fomichev <sdf@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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cd9c21d7 |
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21-Aug-2019 |
Stanislav Fomichev <sdf@google.com> |
selftests/bpf: test_progs: test__skip Export test__skip() to indicate skipped tests and use it in test_send_signal_nmi(). Cc: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Stanislav Fomichev <sdf@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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66bd2ec1 |
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06-Aug-2019 |
Stanislav Fomichev <sdf@google.com> |
selftests/bpf: test_progs: test__printf -> printf Now that test__printf is a simple wraper around printf, let's drop it (and test__vprintf as well). Cc: Andrii Nakryiko <andriin@fb.com> Acked-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Stanislav Fomichev <sdf@google.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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b207edfe |
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27-Jul-2019 |
Andrii Nakryiko <andriin@fb.com> |
selftests/bpf: convert send_signal.c to use subtests Convert send_signal set of tests to be exposed as three sub-tests. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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0ff97e56 |
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27-Jul-2019 |
Andrii Nakryiko <andriin@fb.com> |
selftests/bpf: abstract away test log output This patch changes how test output is printed out. By default, if test had no errors, the only output will be a single line with test number, name, and verdict at the end, e.g.: #31 xdp:OK If test had any errors, all log output captured during test execution will be output after test completes. It's possible to force output of log with `-v` (`--verbose`) option, in which case output won't be buffered and will be output immediately. To support this, individual tests are required to use helper methods for logging: `test__printf()` and `test__vprintf()`. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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4e59afbb |
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15-Jul-2019 |
Ilya Leoshkevich <iii@linux.ibm.com> |
selftests/bpf: skip nmi test when perf hw events are disabled Some setups (e.g. virtual machines) might run with hardware perf events disabled. If this is the case, skip the test_send_signal_nmi test. Add a separate test involving a software perf event. This allows testing the perf event path regardless of hardware perf event support. Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com> Acked-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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16f0efc3 |
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23-May-2019 |
Yonghong Song <yhs@fb.com> |
tools/bpf: add selftest in test_progs for bpf_send_signal() helper The test covered both nmi and tracepoint perf events. $ ./test_progs ... test_send_signal_tracepoint:PASS:tracepoint 0 nsec ... test_send_signal_common:PASS:tracepoint 0 nsec ... test_send_signal_common:PASS:perf_event 0 nsec ... test_send_signal:OK Acked-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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