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authorWaiman Long <longman@redhat.com>2022-03-22 11:20:57 -0400
committerPeter Zijlstra <peterz@infradead.org>2022-04-05 10:24:34 +0200
commitf9e21aa9e6fb11355e54c8949a390d49ca21cde1 (patch)
tree6e6139c7bf141b171e76a16fc9495d22d2573eeb /kernel/locking
parent8b023accc8df70e72f7704d29fead7ca914d6837 (diff)
locking/rwsem: No need to check for handoff bit if wait queue empty
Since commit d257cc8cb8d5 ("locking/rwsem: Make handoff bit handling more consistent"), the handoff bit is always cleared if the wait queue becomes empty. There is no need to check for RWSEM_FLAG_HANDOFF when the wait list is known to be empty. Signed-off-by: Waiman Long <longman@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20220322152059.2182333-2-longman@redhat.com
Diffstat (limited to 'kernel/locking')
-rw-r--r--kernel/locking/rwsem.c9
1 files changed, 4 insertions, 5 deletions
diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c
index acde5d6f1254..b077b1b2d4b3 100644
--- a/kernel/locking/rwsem.c
+++ b/kernel/locking/rwsem.c
@@ -977,12 +977,11 @@ queue:
if (list_empty(&sem->wait_list)) {
/*
* In case the wait queue is empty and the lock isn't owned
- * by a writer or has the handoff bit set, this reader can
- * exit the slowpath and return immediately as its
- * RWSEM_READER_BIAS has already been set in the count.
+ * by a writer, this reader can exit the slowpath and return
+ * immediately as its RWSEM_READER_BIAS has already been set
+ * in the count.
*/
- if (!(atomic_long_read(&sem->count) &
- (RWSEM_WRITER_MASK | RWSEM_FLAG_HANDOFF))) {
+ if (!(atomic_long_read(&sem->count) & RWSEM_WRITER_MASK)) {
/* Provide lock ACQUIRE */
smp_acquire__after_ctrl_dep();
raw_spin_unlock_irq(&sem->wait_lock);