On Mon, Apr 29, 2024 at 03:09:26PM +0200, Mickaël Salaün wrote:
Fix a race condition when running several FIXTURE_TEARDOWN() managing the same resource. This fixes a race condition in the Landlock file system tests when creating or unmounting the same directory.
Using clone3() with CLONE_VFORK guarantees that the child and grandchild test processes are sequentially scheduled. This is implemented with a new clone3_vfork() helper replacing the fork() call.
This avoids triggering this error in __wait_for_test(): Test ended in some other way [127]
Cc: Christian Brauner brauner@kernel.org Cc: David S. Miller davem@davemloft.net Cc: Günther Noack gnoack@google.com Cc: Jakub Kicinski kuba@kernel.org Cc: Kees Cook keescook@chromium.org Cc: Mark Brown broonie@kernel.org Cc: Shuah Khan shuah@kernel.org Cc: Will Drewry wad@chromium.org Fixes: 41cca0542d7c ("selftests/harness: Fix TEST_F()'s vfork handling") Signed-off-by: Mickaël Salaün mic@digikod.net Link: https://lore.kernel.org/r/20240429130931.2394118-5-mic@digikod.net
tools/testing/selftests/kselftest_harness.h | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/kselftest_harness.h b/tools/testing/selftests/kselftest_harness.h index 55699a762c45..9f04638707ae 100644 --- a/tools/testing/selftests/kselftest_harness.h +++ b/tools/testing/selftests/kselftest_harness.h @@ -66,6 +66,8 @@ #include <sys/wait.h> #include <unistd.h> #include <setjmp.h> +#include <syscall.h> +#include <linux/sched.h> #include "kselftest.h" @@ -80,6 +82,17 @@ # define TH_LOG_ENABLED 1 #endif +/* Wait for the child process to end but without sharing memory mapping. */ +static pid_t __attribute__((__unused__)) clone3_vfork(void)
Why "unused"?
+{
- struct clone_args args = {
.flags = CLONE_VFORK,.exit_signal = SIGCHLD,- };
- return syscall(__NR_clone3, &args, sizeof(args));
+}
/**
- TH_LOG()
@@ -1183,7 +1196,7 @@ void __run_test(struct __fixture_metadata *f, fflush(stdout); fflush(stderr);
- t->pid = fork();
- t->pid = clone3_vfork(); if (t->pid < 0) { ksft_print_msg("ERROR SPAWNING TEST CHILD\n"); t->exit_code = KSFT_FAIL;
Regardless, yup, looks good.
Reviewed-by: Kees Cook keescook@chromium.org