[PATCH] selftests/coredump: Fix "socket_detect_userspace_client" test failure

[PATCH] selftests/coredump: Fix "socket_detect_userspace_client" test failure

[Nam Cao]

The coredump.socket_detect_userspace_client test occasionally fails:
    #  RUN           coredump.socket_detect_userspace_client ...
    # stackdump_test.c:500:socket_detect_userspace_client:Expected 0 (0) != WIFEXITED(status) (0)
    # socket_detect_userspace_client: Test terminated by assertion
    #          FAIL  coredump.socket_detect_userspace_client
    not ok 3 coredump.socket_detect_userspace_client

because there is no guarantee that client's write() happens before server's
close(). The client gets terminated SIGPIPE, and thus the test fails.

Add a read() to server to make sure server's close() doesn't happen before
client's write().

Fixes: 7b6724fe9a6b ("selftests/coredump: add tests for AF_UNIX coredumps")
Signed-off-by: Nam Cao <namcao@linutronix.de>
---
 tools/testing/selftests/coredump/stackdump_test.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/tools/testing/selftests/coredump/stackdump_test.c b/tools/testing/selftests/coredump/stackdump_test.c
index 9984413be9f06..68f8e479ac368 100644
--- a/tools/testing/selftests/coredump/stackdump_test.c
+++ b/tools/testing/selftests/coredump/stackdump_test.c
@@ -461,10 +461,15 @@ TEST_F(coredump, socket_detect_userspace_client)
 			_exit(EXIT_FAILURE);
 		}
 
+		ret = read(fd_coredump, &c, 1);
+
 		close(fd_coredump);
 		close(fd_server);
 		close(fd_peer_pidfd);
 		close(fd_core_file);
+
+		if (ret < 1)
+			_exit(EXIT_FAILURE);
 		_exit(EXIT_SUCCESS);
 	}
 	self->pid_coredump_server = pid_coredump_server;
-- 
2.39.5

Re: [PATCH] selftests/coredump: Fix "socket_detect_userspace_client" test failure

[Christian Brauner]

On Fri, 20 Jun 2025 13:02:52 +0200, Nam Cao wrote:
> The coredump.socket_detect_userspace_client test occasionally fails:
>     #  RUN           coredump.socket_detect_userspace_client ...
>     # stackdump_test.c:500:socket_detect_userspace_client:Expected 0 (0) != WIFEXITED(status) (0)
>     # socket_detect_userspace_client: Test terminated by assertion
>     #          FAIL  coredump.socket_detect_userspace_client
>     not ok 3 coredump.socket_detect_userspace_client
> 
> [...]

Applied to the vfs.fixes branch of the vfs/vfs.git tree.
Patches in the vfs.fixes branch should appear in linux-next soon.

Please report any outstanding bugs that were missed during review in a
new review to the original patch series allowing us to drop it.

It's encouraged to provide Acked-bys and Reviewed-bys even though the
patch has now been applied. If possible patch trailers will be updated.

Note that commit hashes shown below are subject to change due to rebase,
trailer updates or similar. If in doubt, please check the listed branch.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git
branch: vfs.fixes

[1/1] selftests/coredump: Fix "socket_detect_userspace_client" test failure
      https://git.kernel.org/vfs/vfs/c/ce9bb9487ef0