2021-02-26 17:53:25

by Davidlohr Bueso

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 <[email protected]>
---
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

2021-03-11 18:26:58

by tip-bot2 for Alexey Makhalov

Subject: [tip: locking/core] kernel/futex: Make futex_wait_requeue_pi() only call fixup_owner()

The following commit has been merged into the locking/core branch of tip:

Commit-ID: a1565aa4699847febfdfd6af3bf06ca17a9e16af
Gitweb: https://git.kernel.org/tip/a1565aa4699847febfdfd6af3bf06ca17a9e16af
Author: Davidlohr Bueso <[email protected]>
AuthorDate: Fri, 26 Feb 2021 09:50:27 -08:00
Committer: Thomas Gleixner <[email protected]>
CommitterDate: Thu, 11 Mar 2021 19:19:17 +01:00

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 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 <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

---
kernel/futex.c | 11 +++++------
1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/kernel/futex.c b/kernel/futex.c
index db8002d..ee09995 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.