[PATCH 3/4] kernel/futex: Move hb unlock out of unqueue_me_pi()

From: Davidlohr Bueso
Date: Fri Feb 26 2021 - 12:52:34 EST


This improves the code readability, and the locking more obvious
as it becomes symmetric for the caller.

Signed-off-by: Davidlohr Bueso <dbueso@xxxxxxx>
---
kernel/futex.c | 10 +++-------
1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/kernel/futex.c b/kernel/futex.c
index ee09995d707b..dcd6132485e1 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -2318,19 +2318,15 @@ static int unqueue_me(struct futex_q *q)

/*
* PI futexes can not be requeued and must remove themself from the
- * hash bucket. The hash bucket lock (i.e. lock_ptr) is held on entry
- * and dropped here.
+ * hash bucket. The hash bucket lock (i.e. lock_ptr) is held.
*/
static void unqueue_me_pi(struct futex_q *q)
- __releases(q->lock_ptr)
{
__unqueue_futex(q);

BUG_ON(!q->pi_state);
put_pi_state(q->pi_state);
q->pi_state = NULL;
-
- spin_unlock(q->lock_ptr);
}

static int __fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
@@ -2913,8 +2909,8 @@ static int futex_lock_pi(u32 __user *uaddr, unsigned int flags,
if (res)
ret = (res < 0) ? res : 0;

- /* Unqueue and drop the lock */
unqueue_me_pi(&q);
+ spin_unlock(q.lock_ptr);
goto out;

out_unlock_put_key:
@@ -3290,8 +3286,8 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags,
if (res)
ret = (res < 0) ? res : 0;

- /* Unqueue and drop the lock. */
unqueue_me_pi(&q);
+ spin_unlock(q.lock_ptr);
}

if (ret == -EINTR) {
--
2.26.2