cb92173d1f0 ("locking/lockdep, cpu/hotplug: Annotate AP thread") was introduced to make lockdep_assert_cpus_held() work in AP thread.
However, the annotation is too strong for that purpose. We don't have to use more than try lock annotation for that.
rwsem_acquire() implies:
1. might be a waiter on contention of the lock. 2. enter to the critical section of the lock.
All we need in here is to act 2, not 1. So trylock version of annotation is sufficient for that purpose. Now that dept partially relies on lockdep annotaions, dept interpets rwsem_acquire() as a potential wait and might report a deadlock by the wait.
Replace it with trylock version of annotation.
Signed-off-by: Byungchul Park byungchul@sk.com --- kernel/cpu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/cpu.c b/kernel/cpu.c index b674fdf96208..06ec3ae1446e 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -538,7 +538,7 @@ int lockdep_is_cpus_held(void)
static void lockdep_acquire_cpus_lock(void) { - rwsem_acquire(&cpu_hotplug_lock.dep_map, 0, 0, _THIS_IP_); + rwsem_acquire(&cpu_hotplug_lock.dep_map, 0, 1, _THIS_IP_); }
static void lockdep_release_cpus_lock(void)