futex: Correct futex_q woken state commentary

Use kernel-doc format to describe struct futex_q. Correct the wakeup definition to eliminate the statement about waking the waiter between the plist_del() and the q->lock_ptr = 0. Note in the comment that PI futexes have a different definition of the woken state. Signed-off-by: Darren Hart <dvhltc@us.ibm.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Dinakar Guniguntala <dino@in.ibm.com> Cc: John Stultz <johnstul@us.ibm.com> LKML-Reference: <20090922053029.8717.62798.stgit@Aeon> Signed-off-by: Ingo Molnar <mingo@elte.hu>

futex: Correct futex_q woken state commentary
Use kernel-doc format to describe struct futex_q. Correct the wakeup definition to eliminate the statement about waking the waiter between the plist_del() and the q->lock_ptr = 0. Note in the comment that PI futexes have a different definition of the woken state. Signed-off-by: Darren Hart <dvhltc@us.ibm.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Dinakar Guniguntala <dino@in.ibm.com> Cc: John Stultz <johnstul@us.ibm.com> LKML-Reference: <20090922053029.8717.62798.stgit@Aeon> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Darren Hart · Ingo Molnar
1 parent d96ee56ce0
Showing 1 changed file with 16 additions and 16 deletions Side-by-side Diff
kernel/futex.c
@@ -89,36 +89,36 @@
 	union futex_key key;
 };
  
-/*
- * We use this hashed waitqueue instead of a normal wait_queue_t, so
+/**
+ * struct futex_q - The hashed futex queue entry, one per waiting task
+ * @task:		the task waiting on the futex
+ * @lock_ptr:		the hash bucket lock
+ * @key:		the key the futex is hashed on
+ * @pi_state:		optional priority inheritance state
+ * @rt_waiter:		rt_waiter storage for use with requeue_pi
+ * @requeue_pi_key:	the requeue_pi target futex key
+ * @bitset:		bitset for the optional bitmasked wakeup
+ *
+ * We use this hashed waitqueue, instead of a normal wait_queue_t, so
  * we can wake only the relevant ones (hashed queues may be shared).
  *
  * A futex_q has a woken state, just like tasks have TASK_RUNNING.
  * It is considered woken when plist_node_empty(&q->list) || q->lock_ptr == 0.
  * The order of wakup is always to make the first condition true, then
- * wake up q->waiter, then make the second condition true.
+ * the second.
+ *
+ * PI futexes are typically woken before they are removed from the hash list via
+ * the rt_mutex code. See unqueue_me_pi().
  */
 struct futex_q {
 	struct plist_node list;
-	/* Waiter reference */
-	struct task_struct *task;
  
-	/* Which hash list lock to use: */
+	struct task_struct *task;
 	spinlock_t *lock_ptr;
-
-	/* Key which the futex is hashed on: */
 	union futex_key key;
-
-	/* Optional priority inheritance state: */
 	struct futex_pi_state *pi_state;
-
-	/* rt_waiter storage for requeue_pi: */
 	struct rt_mutex_waiter *rt_waiter;
-
-	/* The expected requeue pi target futex key: */
 	union futex_key *requeue_pi_key;
-
-	/* Bitset for the optional bitmasked wakeup */
 	u32 bitset;
 };
...	...	@@ -89,36 +89,36 @@
89	89	union futex_key key;
90	90	};
91	91
92		-/*
93		- * We use this hashed waitqueue instead of a normal wait_queue_t, so
	92	+/**
	93	+ * struct futex_q - The hashed futex queue entry, one per waiting task
	94	+ * @task: the task waiting on the futex
	95	+ * @lock_ptr: the hash bucket lock
	96	+ * @key: the key the futex is hashed on
	97	+ * @pi_state: optional priority inheritance state
	98	+ * @rt_waiter: rt_waiter storage for use with requeue_pi
	99	+ * @requeue_pi_key: the requeue_pi target futex key
	100	+ * @bitset: bitset for the optional bitmasked wakeup
	101	+ *
	102	+ * We use this hashed waitqueue, instead of a normal wait_queue_t, so
94	103	* we can wake only the relevant ones (hashed queues may be shared).
95	104	*
96	105	* A futex_q has a woken state, just like tasks have TASK_RUNNING.
97	106	* It is considered woken when plist_node_empty(&q->list) \|\| q->lock_ptr == 0.
98	107	* The order of wakup is always to make the first condition true, then
99		- * wake up q->waiter, then make the second condition true.
	108	+ * the second.
	109	+ *
	110	+ * PI futexes are typically woken before they are removed from the hash list via
	111	+ * the rt_mutex code. See unqueue_me_pi().
100	112	*/
101	113	struct futex_q {
102	114	struct plist_node list;
103		- /* Waiter reference */
104		- struct task_struct *task;
105	115
106		- /* Which hash list lock to use: */
	116	+ struct task_struct *task;
107	117	spinlock_t *lock_ptr;
108		-
109		- /* Key which the futex is hashed on: */
110	118	union futex_key key;
111		-
112		- /* Optional priority inheritance state: */
113	119	struct futex_pi_state *pi_state;
114		-
115		- /* rt_waiter storage for requeue_pi: */
116	120	struct rt_mutex_waiter *rt_waiter;
117		-
118		- /* The expected requeue pi target futex key: */
119	121	union futex_key *requeue_pi_key;
120		-
121		- /* Bitset for the optional bitmasked wakeup */
122	122	u32 bitset;
123	123	};
124	124