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locking/selftests: Add a selftest for check_irq_usage() 

Johannes Berg reported a lockdep problem which could be reproduced by
the special test case introduced in this patch, so add it.

Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210618170110.3699115-5-boqun.feng@gmail.com
This commit is contained in:
Boqun Feng 2021-06-19 01:01:10 +08:00 committed by Peter Zijlstra
parent 7b1f8c6179
commit 8946ccc25e
1 changed files with 65 additions and 0 deletions
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65
lib/locking-selftest.c
View File

@ -53,6 +53,7 @@ __setup("debug_locks_verbose=", setup_debug_locks_verbose);
#define LOCKTYPE_WW 0x10
#define LOCKTYPE_RTMUTEX 0x20
#define LOCKTYPE_LL 0x40
#define LOCKTYPE_SPECIAL 0x80
static struct ww_acquire_ctx t, t2;
static struct ww_mutex o, o2, o3;
@ -2744,6 +2745,66 @@ static void local_lock_tests(void)
pr_cont("\n");
}
static void hardirq_deadlock_softirq_not_deadlock(void)
{
/* mutex_A is hardirq-unsafe and softirq-unsafe */
/* mutex_A -> lock_C */
mutex_lock(&mutex_A);
HARDIRQ_DISABLE();
spin_lock(&lock_C);
spin_unlock(&lock_C);
HARDIRQ_ENABLE();
mutex_unlock(&mutex_A);
/* lock_A is hardirq-safe */
HARDIRQ_ENTER();
spin_lock(&lock_A);
spin_unlock(&lock_A);
HARDIRQ_EXIT();
/* lock_A -> lock_B */
HARDIRQ_DISABLE();
spin_lock(&lock_A);
spin_lock(&lock_B);
spin_unlock(&lock_B);
spin_unlock(&lock_A);
HARDIRQ_ENABLE();
/* lock_B -> lock_C */
HARDIRQ_DISABLE();
spin_lock(&lock_B);
spin_lock(&lock_C);
spin_unlock(&lock_C);
spin_unlock(&lock_B);
HARDIRQ_ENABLE();
/* lock_D is softirq-safe */
SOFTIRQ_ENTER();
spin_lock(&lock_D);
spin_unlock(&lock_D);
SOFTIRQ_EXIT();
/* And lock_D is hardirq-unsafe */
SOFTIRQ_DISABLE();
spin_lock(&lock_D);
spin_unlock(&lock_D);
SOFTIRQ_ENABLE();
/*
* mutex_A -> lock_C -> lock_D is softirq-unsafe -> softirq-safe, not
* deadlock.
*
* lock_A -> lock_B -> lock_C -> lock_D is hardirq-safe ->
* hardirq-unsafe, deadlock.
*/
HARDIRQ_DISABLE();
spin_lock(&lock_C);
spin_lock(&lock_D);
spin_unlock(&lock_D);
spin_unlock(&lock_C);
HARDIRQ_ENABLE();
}
void locking_selftest(void)
{
/*
@ -2872,6 +2933,10 @@ void locking_selftest(void)
local_lock_tests();
print_testname("hardirq_unsafe_softirq_safe");
dotest(hardirq_deadlock_softirq_not_deadlock, FAILURE, LOCKTYPE_SPECIAL);
pr_cont("\n");
if (unexpected_testcase_failures) {
printk("-----------------------------------------------------------------\n");
debug_locks = 0;