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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 <peterz@infradead.org>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210318172814.4400-3-longman@redhat.com
This commit is contained in:
Waiman Long 2021-03-18 13:28:11 -04:00 committed by Ingo Molnar
parent 01438749e3
commit 2ea55bbba2
1 changed files with 14 additions and 3 deletions
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17
kernel/locking/locktorture.c
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@ -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,