The following commit has been merged into the locking/core branch of tip: Commit-ID: 2ea55bbba23e9d36996299664d618393c8602646 Gitweb: https://git.kernel.org/tip/2ea55bbba23e9d36996299664d618393c8602646 Author: Waiman Long <long...@redhat.com> AuthorDate: Thu, 18 Mar 2021 13:28:11 -04:00 Committer: Ingo Molnar <mi...@kernel.org> CommitterDate: Fri, 19 Mar 2021 12:13:09 +01:00
locking/locktorture: Fix false positive circular locking splat in ww_mutex test In order to avoid false positive circular locking lockdep splat when runnng the ww_mutex torture test, we need to make sure that the ww_mutexes have the same lock class as the acquire_ctx. This means the ww_mutexes must have the same lockdep key as the acquire_ctx. Unfortunately the current DEFINE_WW_MUTEX() macro fails to do that. As a result, we add an init method for the ww_mutex test to do explicit ww_mutex_init()'s of the ww_mutexes to avoid the false positive warning. Suggested-by: Peter Zijlstra <pet...@infradead.org> Signed-off-by: Waiman Long <long...@redhat.com> Signed-off-by: Ingo Molnar <mi...@kernel.org> Link: https://lore.kernel.org/r/20210318172814.4400-3-long...@redhat.com --- kernel/locking/locktorture.c | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c index 0ab94e1..3c27f43 100644 --- a/kernel/locking/locktorture.c +++ b/kernel/locking/locktorture.c @@ -357,10 +357,20 @@ static struct lock_torture_ops mutex_lock_ops = { }; #include <linux/ww_mutex.h> +/* + * The torture ww_mutexes should belong to the same lock class as + * torture_ww_class to avoid lockdep problem. The ww_mutex_init() + * function is called for initialization to ensure that. + */ static DEFINE_WD_CLASS(torture_ww_class); -static DEFINE_WW_MUTEX(torture_ww_mutex_0, &torture_ww_class); -static DEFINE_WW_MUTEX(torture_ww_mutex_1, &torture_ww_class); -static DEFINE_WW_MUTEX(torture_ww_mutex_2, &torture_ww_class); +static struct ww_mutex torture_ww_mutex_0, torture_ww_mutex_1, torture_ww_mutex_2; + +static void torture_ww_mutex_init(void) +{ + ww_mutex_init(&torture_ww_mutex_0, &torture_ww_class); + ww_mutex_init(&torture_ww_mutex_1, &torture_ww_class); + ww_mutex_init(&torture_ww_mutex_2, &torture_ww_class); +} static int torture_ww_mutex_lock(void) __acquires(torture_ww_mutex_0) @@ -418,6 +428,7 @@ __releases(torture_ww_mutex_2) } static struct lock_torture_ops ww_mutex_lock_ops = { + .init = torture_ww_mutex_init, .writelock = torture_ww_mutex_lock, .write_delay = torture_mutex_delay, .task_boost = torture_boost_dummy,
