From: "Mickaël Salaün" <mic@digikod.net>
To: Christian Brauner <brauner@kernel.org>,
Jakub Kicinski <kuba@kernel.org>,
Kees Cook <keescook@chromium.org>,
Mark Brown <broonie@kernel.org>,
Shengyu Li <shengyu.li.evgeny@gmail.com>,
Shuah Khan <shuah@kernel.org>
Cc: "Mickaël Salaün" <mic@digikod.net>,
"David S . Miller" <davem@davemloft.net>,
"Günther Noack" <gnoack@google.com>,
"Will Drewry" <wad@chromium.org>,
"kernel test robot" <oliver.sang@intel.com>,
linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org
Subject: [PATCH v1 4/5] selftests/harness: Fix interleaved scheduling leading to race conditions
Date: Fri, 26 Apr 2024 19:22:51 +0200 [thread overview]
Message-ID: <20240426172252.1862930-5-mic@digikod.net> (raw)
In-Reply-To: <20240426172252.1862930-1-mic@digikod.net>
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
next prev parent reply other threads:[~2024-04-26 17:23 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-26 17:22 [PATCH v1 0/5] Fix Kselftest's vfork() side effects Mickaël Salaün
2024-04-26 17:22 ` [PATCH v1 1/5] selftests/pidfd: Fix config for pidfd_setns_test Mickaël Salaün
2024-04-26 19:37 ` Kees Cook
2024-04-26 17:22 ` [PATCH v1 2/5] selftests/landlock: Fix FS tests when run on a private mount point Mickaël Salaün
2024-04-26 19:38 ` Kees Cook
2024-04-29 12:39 ` Mickaël Salaün
2024-04-26 17:22 ` [PATCH v1 3/5] selftests/harness: Fix fixture teardown Mickaël Salaün
2024-04-26 19:40 ` Kees Cook
2024-04-26 17:22 ` Mickaël Salaün [this message]
2024-04-26 17:22 ` [PATCH v1 5/5] selftests/harness: Fix vfork() side effects and uncaught errors Mickaël Salaün
2024-04-26 19:47 ` Kees Cook
2024-04-29 12:39 ` Mickaël Salaün
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