Unverified Commit cd89597b authored by Christian Brauner's avatar Christian Brauner
Browse files

tests: add waitid() tests for non-blocking pidfds 



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

Signed-off-by: default avatarChristian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: default avatarJosh Triplett <josh@joshtriplett.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: linux-kselftest@vger.kernel.org
Link: https://lore.kernel.org/r/20200902102130.147672-5-christian.brauner@ubuntu.com
parent 09d1de1a

tools/testing/selftests/pidfd/pidfd.h

+4 −0
Original line number Diff line number Diff line
@@ -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.

tools/testing/selftests/pidfd/pidfd_wait.c

+90 −1
Original line number Diff line number Diff line
@@ -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 +138,88 @@ 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");

	}



	ret = sys_waitid(P_PIDFD, pidfd, &info, WEXITED, NULL);

	ASSERT_LT(ret, 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.

	 */

	ret = sys_waitid(P_PIDFD, pidfd, &info, WEXITED, NULL);

	ASSERT_LT(ret, 0);

	ASSERT_EQ(errno, EAGAIN);



	/*

	 * Callers need to continue seeing 0 with non-blocking pidfd and

	 * WNOHANG raised explicitly when child processes exist but none have

	 * exited.

	 */

	ret = sys_waitid(P_PIDFD, pidfd, &info, WEXITED | WNOHANG, NULL);

	ASSERT_EQ(ret, 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);

	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