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-rw-r--r--kernel/locking/rwsem-xadd.c19
1 files changed, 9 insertions, 10 deletions
diff --git a/kernel/locking/rwsem-xadd.c b/kernel/locking/rwsem-xadd.c
index e795908f3607..a90336779375 100644
--- a/kernel/locking/rwsem-xadd.c
+++ b/kernel/locking/rwsem-xadd.c
@@ -352,16 +352,15 @@ static inline bool rwsem_can_spin_on_owner(struct rw_semaphore *sem)
struct task_struct *owner;
bool ret = true;
+ BUILD_BUG_ON(!rwsem_has_anonymous_owner(RWSEM_OWNER_UNKNOWN));
+
if (need_resched())
return false;
rcu_read_lock();
owner = READ_ONCE(sem->owner);
- if (!rwsem_owner_is_writer(owner)) {
- /*
- * Don't spin if the rwsem is readers owned.
- */
- ret = !rwsem_owner_is_reader(owner);
+ if (!owner || !is_rwsem_owner_spinnable(owner)) {
+ ret = !owner; /* !owner is spinnable */
goto done;
}
@@ -382,11 +381,11 @@ static noinline bool rwsem_spin_on_owner(struct rw_semaphore *sem)
{
struct task_struct *owner = READ_ONCE(sem->owner);
- if (!rwsem_owner_is_writer(owner))
- goto out;
+ if (!is_rwsem_owner_spinnable(owner))
+ return false;
rcu_read_lock();
- while (sem->owner == owner) {
+ while (owner && (READ_ONCE(sem->owner) == owner)) {
/*
* Ensure we emit the owner->on_cpu, dereference _after_
* checking sem->owner still matches owner, if that fails,
@@ -408,12 +407,12 @@ static noinline bool rwsem_spin_on_owner(struct rw_semaphore *sem)
cpu_relax();
}
rcu_read_unlock();
-out:
+
/*
* If there is a new owner or the owner is not set, we continue
* spinning.
*/
- return !rwsem_owner_is_reader(READ_ONCE(sem->owner));
+ return is_rwsem_owner_spinnable(READ_ONCE(sem->owner));
}
static bool rwsem_optimistic_spin(struct rw_semaphore *sem)