diff options
author | Boqun Feng <boqun.feng@gmail.com> | 2021-06-19 01:01:10 +0800 |
---|---|---|
committer | Peter Zijlstra <peterz@infradead.org> | 2021-06-22 16:42:07 +0200 |
commit | 8946ccc25ed22d957ca7f0b6fac1dcf6d25eaf1f (patch) | |
tree | 46db1566de9958bee8ee674952b46c7b10ad3b87 /lib | |
parent | 7b1f8c6179769af6ffa055e1169610b51d71edd5 (diff) |
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
Diffstat (limited to 'lib')
-rw-r--r-- | lib/locking-selftest.c | 65 |
1 files changed, 65 insertions, 0 deletions
diff --git a/lib/locking-selftest.c b/lib/locking-selftest.c index 2d85abac1744..5c50b0910396 100644 --- a/lib/locking-selftest.c +++ b/lib/locking-selftest.c @@ -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; |