Verify that the PIDFD_NONBLOCK flag works with pidfd_open() and that waitid() with a non-blocking pidfd returns EAGAIN:
TAP version 13 1..3 # Starting 3 tests from 1 test cases. # RUN global.wait_simple ... # OK global.wait_simple ok 1 global.wait_simple # RUN global.wait_states ... # OK global.wait_states ok 2 global.wait_states # RUN global.wait_nonblock ... # OK global.wait_nonblock ok 3 global.wait_nonblock # PASSED: 3 / 3 tests passed. # Totals: pass:3 fail:0 xfail:0 xpass:0 skip:0 error:0
Cc: Shuah Khan shuah@kernel.org Cc: linux-kselftest@vger.kernel.org Signed-off-by: Christian Brauner christian.brauner@ubuntu.com --- tools/testing/selftests/pidfd/pidfd.h | 4 ++ tools/testing/selftests/pidfd/pidfd_wait.c | 83 +++++++++++++++++++++- 2 files changed, 86 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/pidfd/pidfd.h b/tools/testing/selftests/pidfd/pidfd.h index a2c80914e3dc..01f8d3c0cf2c 100644 --- a/tools/testing/selftests/pidfd/pidfd.h +++ b/tools/testing/selftests/pidfd/pidfd.h @@ -46,6 +46,10 @@ #define __NR_pidfd_getfd -1 #endif
+#ifndef PIDFD_NONBLOCK +#define PIDFD_NONBLOCK O_NONBLOCK +#endif + /* * The kernel reserves 300 pids via RESERVED_PIDS in kernel/pid.c * That means, when it wraps around any pid < 300 will be skipped. diff --git a/tools/testing/selftests/pidfd/pidfd_wait.c b/tools/testing/selftests/pidfd/pidfd_wait.c index 075c716f6fb8..cefce4d3d2f6 100644 --- a/tools/testing/selftests/pidfd/pidfd_wait.c +++ b/tools/testing/selftests/pidfd/pidfd_wait.c @@ -21,6 +21,11 @@
#define ptr_to_u64(ptr) ((__u64)((uintptr_t)(ptr)))
+/* Attempt to de-conflict with the selftests tree. */ +#ifndef SKIP +#define SKIP(s, ...) XFAIL(s, ##__VA_ARGS__) +#endif + static pid_t sys_clone3(struct clone_args *args) { return syscall(__NR_clone3, args, sizeof(struct clone_args)); @@ -65,7 +70,7 @@ TEST(wait_simple) pidfd = -1;
pid = sys_clone3(&args); - ASSERT_GE(pid, 1); + ASSERT_GE(pid, 0);
if (pid == 0) exit(EXIT_SUCCESS); @@ -133,4 +138,80 @@ TEST(wait_states) EXPECT_EQ(close(pidfd), 0); }
+TEST(wait_nonblock) +{ + int pidfd, status = 0; + unsigned int flags = 0; + pid_t parent_tid = -1; + struct clone_args args = { + .parent_tid = ptr_to_u64(&parent_tid), + .flags = CLONE_PARENT_SETTID, + .exit_signal = SIGCHLD, + }; + int ret; + pid_t pid; + siginfo_t info = { + .si_signo = 0, + }; + + /* + * Callers need to see ECHILD with non-blocking pidfds when no child + * processes exists. + */ + pidfd = sys_pidfd_open(getpid(), PIDFD_NONBLOCK); + EXPECT_GE(pidfd, 0) { + /* pidfd_open() doesn't support PIDFD_NONBLOCK. */ + ASSERT_EQ(errno, EINVAL); + SKIP(return, "Skipping PIDFD_NONBLOCK test"); + } + + pid = sys_waitid(P_PIDFD, pidfd, &info, WEXITED, NULL); + ASSERT_LT(pid, 0); + ASSERT_EQ(errno, ECHILD); + EXPECT_EQ(close(pidfd), 0); + + pid = sys_clone3(&args); + ASSERT_GE(pid, 0); + + if (pid == 0) { + kill(getpid(), SIGSTOP); + exit(EXIT_SUCCESS); + } + + pidfd = sys_pidfd_open(pid, PIDFD_NONBLOCK); + EXPECT_GE(pidfd, 0) { + /* pidfd_open() doesn't support PIDFD_NONBLOCK. */ + ASSERT_EQ(errno, EINVAL); + SKIP(return, "Skipping PIDFD_NONBLOCK test"); + } + + flags = fcntl(pidfd, F_GETFL, 0); + ASSERT_GT(flags, 0); + ASSERT_GT((flags & O_NONBLOCK), 0); + + /* + * Callers need to see EAGAIN/EWOULDBLOCK with non-blocking pidfd when + * child processes exist but none have exited. + */ + pid = sys_waitid(P_PIDFD, pidfd, &info, WEXITED, NULL); + ASSERT_LT(pid, 0); + ASSERT_EQ(errno, EAGAIN); + + ASSERT_EQ(sys_waitid(P_PIDFD, pidfd, &info, WSTOPPED, NULL), 0); + ASSERT_EQ(info.si_signo, SIGCHLD); + ASSERT_EQ(info.si_code, CLD_STOPPED); + ASSERT_EQ(info.si_pid, parent_tid); + + ASSERT_EQ(sys_pidfd_send_signal(pidfd, SIGCONT, NULL, 0), 0); + + ASSERT_EQ(fcntl(pidfd, F_SETFL, (flags & ~O_NONBLOCK)), 0); + + ASSERT_EQ(sys_waitid(P_PIDFD, pidfd, &info, WEXITED, NULL), 0); + ASSERT_EQ(info.si_signo, SIGCHLD); + ASSERT_EQ(info.si_code, CLD_EXITED); + ASSERT_EQ(info.si_pid, parent_tid); + + EXPECT_EQ(close(pidfd), 0); +} + TEST_HARNESS_MAIN