linux-kernel - [PATCH 2/4] kernel/futex: Make futex_wait_requeue_pi() only call fixup

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Date:   Fri, 26 Feb 2021 09:50:27 -0800
From:   Davidlohr Bueso <dave@...olabs.net>
To:     tglx@...utronix.de
Cc:     mingo@...hat.com, peterz@...radead.org, dvhart@...radead.org,
        dave@...olabs.net, linux-kernel@...r.kernel.org,
        Davidlohr Bueso <dbueso@...e.de>
Subject: [PATCH 2/4] kernel/futex: Make futex_wait_requeue_pi() only call fixup_owner()

A small cleanup that allows for fixup_pi_state_owner() only to be
called from fixup_owner(), and make the requeue_pi uniformly call
fixup_owner() regardless of the state in which the fixup is actually
needed. Of course this makes the caller's first pi_state->owner != current
check redundant, but that should't really matter.

Signed-off-by: Davidlohr Bueso <dbueso@...e.de>
---
 kernel/futex.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/kernel/futex.c b/kernel/futex.c
index db8002dbca7a..ee09995d707b 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -3241,15 +3241,14 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags,
 	 * reference count.
 	 */
 
-	/* Check if the requeue code acquired the second futex for us. */
+	/*
+	 * Check if the requeue code acquired the second futex for us and do
+	 * any pertinent fixup.
+	 */
 	if (!q.rt_waiter) {
-		/*
-		 * Got the lock. We might not be the anticipated owner if we
-		 * did a lock-steal - fix up the PI-state in that case.
-		 */
 		if (q.pi_state && (q.pi_state->owner != current)) {
 			spin_lock(q.lock_ptr);
-			ret = fixup_pi_state_owner(uaddr2, &q, current);
+			ret = fixup_owner(uaddr2, &q, true);
 			/*
 			 * Drop the reference to the pi state which
 			 * the requeue_pi() code acquired for us.
-- 
2.26.2