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| author | Li Zhijian <lizhijian@fujitsu.com> | 2022-09-01 06:10:07 +0300 |
|---|---|---|
| committer | Shuah Khan <skhan@linuxfoundation.org> | 2022-10-30 11:23:41 +0300 |
| commit | 88e1f16ba58665e9edfce437ea487da2fa759af9 (patch) | |
| tree | dd1a2821f9272782756bd78c17b352ea80673db4 /tools | |
| parent | cb05c81ada76a30a25a5f79b249375e33473af33 (diff) | |
| download | linux-88e1f16ba58665e9edfce437ea487da2fa759af9.tar.xz | |
ksefltests: pidfd: Fix wait_states: Test terminated by timeout
0Day/LKP observed that the kselftest blocks forever since one of the
pidfd_wait doesn't terminate in 1 of 30 runs. After digging into
the source, we found that it blocks at:
ASSERT_EQ(sys_waitid(P_PIDFD, pidfd, &info, WCONTINUED, NULL), 0);
wait_states has below testing flow:
CHILD PARENT
---------------+--------------
1 STOP itself
2 WAIT for CHILD STOPPED
3 SIGNAL CHILD to CONT
4 CONT
5 STOP itself
5' WAIT for CHILD CONT
6 WAIT for CHILD STOPPED
The problem is that the kernel cannot ensure the order of 5 and 5', once
5 goes first, the test will fail.
we can reproduce it by:
$ while true; do make run_tests -C pidfd; done
Introduce a blocking read in child process to make sure the parent can
check its WCONTINUED.
CC: Philip Li <philip.li@intel.com>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Li Zhijian <lizhijian@fujitsu.com>
Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Diffstat (limited to 'tools')
| -rw-r--r-- | tools/testing/selftests/pidfd/pidfd_wait.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/tools/testing/selftests/pidfd/pidfd_wait.c b/tools/testing/selftests/pidfd/pidfd_wait.c index 070c1c876df1..c3e2a3041f55 100644 --- a/tools/testing/selftests/pidfd/pidfd_wait.c +++ b/tools/testing/selftests/pidfd/pidfd_wait.c @@ -95,20 +95,28 @@ TEST(wait_states) .flags = CLONE_PIDFD | CLONE_PARENT_SETTID, .exit_signal = SIGCHLD, }; + int pfd[2]; pid_t pid; siginfo_t info = { .si_signo = 0, }; + ASSERT_EQ(pipe(pfd), 0); pid = sys_clone3(&args); ASSERT_GE(pid, 0); if (pid == 0) { + char buf[2]; + + close(pfd[1]); kill(getpid(), SIGSTOP); + ASSERT_EQ(read(pfd[0], buf, 1), 1); + close(pfd[0]); kill(getpid(), SIGSTOP); exit(EXIT_SUCCESS); } + close(pfd[0]); ASSERT_EQ(sys_waitid(P_PIDFD, pidfd, &info, WSTOPPED, NULL), 0); ASSERT_EQ(info.si_signo, SIGCHLD); ASSERT_EQ(info.si_code, CLD_STOPPED); @@ -117,6 +125,8 @@ TEST(wait_states) ASSERT_EQ(sys_pidfd_send_signal(pidfd, SIGCONT, NULL, 0), 0); ASSERT_EQ(sys_waitid(P_PIDFD, pidfd, &info, WCONTINUED, NULL), 0); + ASSERT_EQ(write(pfd[1], "C", 1), 1); + close(pfd[1]); ASSERT_EQ(info.si_signo, SIGCHLD); ASSERT_EQ(info.si_code, CLD_CONTINUED); ASSERT_EQ(info.si_pid, parent_tid); |