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From: Peter Zijlstra <peterz@infradead.org>
To: tglx@linutronix.de
Cc: mingo@kernel.org, juri.lelli@arm.com, rostedt@goodmis.org,
	xlpang@redhat.com, bigeasy@linutronix.de,
	linux-kernel@vger.kernel.org, mathieu.desnoyers@efficios.com,
	jdesfossez@efficios.com, bristot@redhat.com,
	dvhart@infradead.org, peterz@infradead.org
Subject: [PATCH -v5 03/14] futex: Cleanup variable names for futex_top_waiter()
Date: Sat, 04 Mar 2017 10:27:20 +0100	[thread overview]
Message-ID: <20170304093558.942824572@infradead.org> (raw)
In-Reply-To: 20170304092717.762954142@infradead.org

[-- Attachment #1: peterz-futex-cleanup-top_waiter.patch --]
[-- Type: text/plain, Size: 3384 bytes --]

futex_top_waiter() returns the top-waiter on the pi_mutex. Assinging
this to a variable 'match' totally obscures the code.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 kernel/futex.c |   30 +++++++++++++++---------------
 1 file changed, 15 insertions(+), 15 deletions(-)

--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1120,14 +1120,14 @@ static int attach_to_pi_owner(u32 uval,
 static int lookup_pi_state(u32 uval, struct futex_hash_bucket *hb,
 			   union futex_key *key, struct futex_pi_state **ps)
 {
-	struct futex_q *match = futex_top_waiter(hb, key);
+	struct futex_q *top_waiter = futex_top_waiter(hb, key);
 
 	/*
 	 * If there is a waiter on that futex, validate it and
 	 * attach to the pi_state when the validation succeeds.
 	 */
-	if (match)
-		return attach_to_pi_state(uval, match->pi_state, ps);
+	if (top_waiter)
+		return attach_to_pi_state(uval, top_waiter->pi_state, ps);
 
 	/*
 	 * We are the first waiter - try to look up the owner based on
@@ -1174,7 +1174,7 @@ static int futex_lock_pi_atomic(u32 __us
 				struct task_struct *task, int set_waiters)
 {
 	u32 uval, newval, vpid = task_pid_vnr(task);
-	struct futex_q *match;
+	struct futex_q *top_waiter;
 	int ret;
 
 	/*
@@ -1200,9 +1200,9 @@ static int futex_lock_pi_atomic(u32 __us
 	 * Lookup existing state first. If it exists, try to attach to
 	 * its pi_state.
 	 */
-	match = futex_top_waiter(hb, key);
-	if (match)
-		return attach_to_pi_state(uval, match->pi_state, ps);
+	top_waiter = futex_top_waiter(hb, key);
+	if (top_waiter)
+		return attach_to_pi_state(uval, top_waiter->pi_state, ps);
 
 	/*
 	 * No waiter and user TID is 0. We are here because the
@@ -1292,11 +1292,11 @@ static void mark_wake_futex(struct wake_
 	q->lock_ptr = NULL;
 }
 
-static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *this,
+static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *top_waiter,
 			 struct futex_hash_bucket *hb)
 {
 	struct task_struct *new_owner;
-	struct futex_pi_state *pi_state = this->pi_state;
+	struct futex_pi_state *pi_state = top_waiter->pi_state;
 	u32 uninitialized_var(curval), newval;
 	DEFINE_WAKE_Q(wake_q);
 	bool deboost;
@@ -1317,11 +1317,11 @@ static int wake_futex_pi(u32 __user *uad
 
 	/*
 	 * It is possible that the next waiter (the one that brought
-	 * this owner to the kernel) timed out and is no longer
+	 * top_waiter owner to the kernel) timed out and is no longer
 	 * waiting on the lock.
 	 */
 	if (!new_owner)
-		new_owner = this->task;
+		new_owner = top_waiter->task;
 
 	/*
 	 * We pass it to the next owner. The WAITERS bit is always
@@ -2631,7 +2631,7 @@ static int futex_unlock_pi(u32 __user *u
 	u32 uninitialized_var(curval), uval, vpid = task_pid_vnr(current);
 	union futex_key key = FUTEX_KEY_INIT;
 	struct futex_hash_bucket *hb;
-	struct futex_q *match;
+	struct futex_q *top_waiter;
 	int ret;
 
 retry:
@@ -2655,9 +2655,9 @@ static int futex_unlock_pi(u32 __user *u
 	 * all and we at least want to know if user space fiddled
 	 * with the futex value instead of blindly unlocking.
 	 */
-	match = futex_top_waiter(hb, &key);
-	if (match) {
-		ret = wake_futex_pi(uaddr, uval, match, hb);
+	top_waiter = futex_top_waiter(hb, &key);
+	if (top_waiter) {
+		ret = wake_futex_pi(uaddr, uval, top_waiter, hb);
 		/*
 		 * In case of success wake_futex_pi dropped the hash
 		 * bucket lock.

  parent reply	other threads:[~2017-03-04 11:44 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-03-04  9:27 [PATCH -v5 00/14] the saga of FUTEX_UNLOCK_PI wobbles continues Peter Zijlstra
2017-03-04  9:27 ` [PATCH -v5 01/14] futex: Fix potential use-after-free in FUTEX_REQUEUE_PI Peter Zijlstra
2017-03-14 20:48   ` [tip:locking/urgent] " tip-bot for Peter Zijlstra
2017-03-04  9:27 ` [PATCH -v5 02/14] futex: Add missing error handling to FUTEX_REQUEUE_PI Peter Zijlstra
2017-03-14 20:49   ` [tip:locking/urgent] " tip-bot for Peter Zijlstra
2017-03-04  9:27 ` Peter Zijlstra [this message]
2017-03-04  9:27 ` [PATCH -v5 04/14] futex: Use smp_store_release() in mark_wake_futex() Peter Zijlstra
2017-03-04  9:27 ` [PATCH -v5 05/14] futex: Remove rt_mutex_deadlock_account_*() Peter Zijlstra
2017-03-04  9:27 ` [PATCH -v5 06/14] futex,rt_mutex: Provide futex specific rt_mutex API Peter Zijlstra
2017-03-04  9:27 ` [PATCH -v5 07/14] futex: Change locking rules Peter Zijlstra
2017-03-07 13:22   ` Thomas Gleixner
2017-03-07 16:47     ` Sebastian Andrzej Siewior
2017-03-07 18:01       ` Peter Zijlstra
2017-03-04  9:27 ` [PATCH -v5 08/14] futex: Cleanup refcounting Peter Zijlstra
2017-03-04  9:27 ` [PATCH -v5 09/14] futex: Rework inconsistent rt_mutex/futex_q state Peter Zijlstra
2017-03-07 13:26   ` Thomas Gleixner
2017-03-04  9:27 ` [PATCH -v5 10/14] futex: Pull rt_mutex_futex_unlock() out from under hb->lock Peter Zijlstra
2017-03-07 14:08   ` Thomas Gleixner
2017-03-07 18:01     ` Peter Zijlstra
2017-03-04  9:27 ` [PATCH -v5 11/14] futex,rt_mutex: Introduce rt_mutex_init_waiter() Peter Zijlstra
2017-03-04  9:27 ` [PATCH -v5 12/14] futex,rt_mutex: Restructure rt_mutex_finish_proxy_lock() Peter Zijlstra
2017-03-07 14:18   ` Thomas Gleixner
2017-03-07 17:57     ` Peter Zijlstra
2017-03-07 17:59       ` Thomas Gleixner
2017-03-08 15:29   ` [PATCH] futex: move debug_rt_mutex_free_waiter() further down Sebastian Andrzej Siewior
2017-03-08 15:37     ` Sebastian Andrzej Siewior
2017-03-08 16:21       ` Steven Rostedt
2017-03-08 16:20     ` Steven Rostedt
2017-03-13  9:16     ` Peter Zijlstra
2017-03-04  9:27 ` [PATCH -v5 13/14] futex: Rework futex_lock_pi() to use rt_mutex_*_proxy_lock() Peter Zijlstra
2017-03-04  9:27 ` [PATCH -v5 14/14] futex: futex_unlock_pi() determinism Peter Zijlstra
2017-03-07 14:31   ` Thomas Gleixner
2017-03-07 17:59     ` Peter Zijlstra
2017-03-13  9:25     ` Peter Zijlstra
2017-03-13 14:25       ` Thomas Gleixner
2017-03-13 15:11         ` Peter Zijlstra

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