linux-kernel - [tip: locking/core] futex: Clean up stale comments

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Message-ID: <162923124464.25758.10857186183431942989.tip-bot2@tip-bot2>
Date:   Tue, 17 Aug 2021 20:14:04 -0000
From:   "tip-bot2 for Thomas Gleixner" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: locking/core] futex: Clean up stale comments

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

Commit-ID:     c363b7ed79253d5b53494197f6ae625cff64694f
Gitweb:        https://git.kernel.org/tip/c363b7ed79253d5b53494197f6ae625cff64694f
Author:        Thomas Gleixner <tglx@...utronix.de>
AuthorDate:    Sun, 15 Aug 2021 23:29:06 +02:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Tue, 17 Aug 2021 19:05:39 +02:00

futex: Clean up stale comments

The futex key reference mechanism is long gone. Clean up the stale comments
which still mention it.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Link: https://lore.kernel.org/r/20210815211305.249178312@linutronix.de
---
 kernel/futex.c | 18 +++++++-----------
 1 file changed, 7 insertions(+), 11 deletions(-)

diff --git a/kernel/futex.c b/kernel/futex.c
index a1f27fd..bc5395e 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1354,7 +1354,7 @@ static int lock_pi_update_atomic(u32 __user *uaddr, u32 uval, u32 newval)
  *  -  1 - acquired the lock;
  *  - <0 - error
  *
- * The hb->lock and futex_key refs shall be held by the caller.
+ * The hb->lock must be held by the caller.
  *
  * @exiting is only set when the return value is -EBUSY. If so, this holds
  * a refcount on the exiting task on return and the caller needs to drop it
@@ -2621,8 +2621,7 @@ static void futex_wait_queue_me(struct futex_hash_bucket *hb, struct futex_q *q,
  *
  * Setup the futex_q and locate the hash_bucket.  Get the futex value and
  * compare it with the expected value.  Handle atomic faults internally.
- * Return with the hb lock held and a q.key reference on success, and unlocked
- * with no q.key reference on failure.
+ * Return with the hb lock held on success, and unlocked on failure.
  *
  * Return:
  *  -  0 - uaddr contains val and hb has been locked;
@@ -2700,8 +2699,8 @@ static int futex_wait(u32 __user *uaddr, unsigned int flags, u32 val,
 			       current->timer_slack_ns);
 retry:
 	/*
-	 * Prepare to wait on uaddr. On success, holds hb lock and increments
-	 * q.key refs.
+	 * Prepare to wait on uaddr. On success, it holds hb->lock and q
+	 * is initialized.
 	 */
 	ret = futex_wait_setup(uaddr, val, flags, &q, &hb);
 	if (ret)
@@ -2712,7 +2711,6 @@ retry:
 
 	/* If we were woken (and unqueued), we succeeded, whatever. */
 	ret = 0;
-	/* unqueue_me() drops q.key ref */
 	if (!unqueue_me(&q))
 		goto out;
 	ret = -ETIMEDOUT;
@@ -3205,8 +3203,8 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags,
 	q.requeue_pi_key = &key2;
 
 	/*
-	 * Prepare to wait on uaddr. On success, increments q.key (key1) ref
-	 * count.
+	 * Prepare to wait on uaddr. On success, it holds hb->lock and q
+	 * is initialized.
 	 */
 	ret = futex_wait_setup(uaddr, val, flags, &q, &hb);
 	if (ret)
@@ -3235,9 +3233,7 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags,
 	 * In order for us to be here, we know our q.key == key2, and since
 	 * we took the hb->lock above, we also know that futex_requeue() has
 	 * completed and we no longer have to concern ourselves with a wakeup
-	 * race with the atomic proxy lock acquisition by the requeue code. The
-	 * futex_requeue dropped our key1 reference and incremented our key2
-	 * reference count.
+	 * race with the atomic proxy lock acquisition by the requeue code.
 	 */
 
 	/*