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lockdep/selftest: Add spin_nest_lock test 

Add a self test case to test the behavior for the following case:

	lock(A);
	lock_nest_lock(C1, A);
	lock(B);
	lock_nest_lock(C2, A);

This is a reproducer for a problem[1] reported by Chris Wilson, and is
helpful to prevent this.

[1]: https://lore.kernel.org/lkml/160390684819.31966.12048967113267928793@build.alporthouse.com/

Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20201102053743.450459-2-boqun.feng@gmail.com
This commit is contained in:
Boqun Feng 2020-11-02 13:37:42 +08:00 committed by Peter Zijlstra
parent a2e9ae58d5
commit e04ce676e7
1 changed files with 17 additions and 0 deletions
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17
lib/locking-selftest.c
View File

@ -2009,6 +2009,19 @@ static void ww_test_spin_nest_unlocked(void)
U(A);
}
/* This is not a deadlock, because we have X1 to serialize Y1 and Y2 */
static void ww_test_spin_nest_lock(void)
{
spin_lock(&lock_X1);
spin_lock_nest_lock(&lock_Y1, &lock_X1);
spin_lock(&lock_A);
spin_lock_nest_lock(&lock_Y2, &lock_X1);
spin_unlock(&lock_A);
spin_unlock(&lock_Y2);
spin_unlock(&lock_Y1);
spin_unlock(&lock_X1);
}
static void ww_test_unneeded_slow(void)
{
WWAI(&t);
@ -2226,6 +2239,10 @@ static void ww_tests(void)
dotest(ww_test_spin_nest_unlocked, FAILURE, LOCKTYPE_WW);
pr_cont("\n");
print_testname("spinlock nest test");
dotest(ww_test_spin_nest_lock, SUCCESS, LOCKTYPE_WW);
pr_cont("\n");
printk(" -----------------------------------------------------\n");
printk(" |block | try |context|\n");
printk(" -----------------------------------------------------\n");