Messages in this thread Patch in this message | | | From | Mickaël Salaün <> | Subject | [PATCH v1 4/5] selftests/harness: Fix interleaved scheduling leading to race conditions | Date | Fri, 26 Apr 2024 19:22:51 +0200 |
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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/20240426172252.1862930-5-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 73491efbae9e..d2dd246a3843 100644 --- a/tools/testing/selftests/kselftest_harness.h +++ b/tools/testing/selftests/kselftest_harness.h @@ -67,6 +67,8 @@ #include <sys/wait.h> #include <unistd.h> #include <setjmp.h> +#include <syscall.h> +#include <linux/sched.h> #include "kselftest.h" @@ -81,6 +83,17 @@ # 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) +{ + struct clone_args args = { + .flags = CLONE_VFORK, + .exit_signal = SIGCHLD, + }; + + return syscall(__NR_clone3, &args, sizeof(args)); +} + /** * TH_LOG() * @@ -1180,7 +1193,7 @@ 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; -- 2.44.0
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