sched/wait: Disambiguate wq_entry->task_list and wq_head->task_list naming

So I've noticed a number of instances where it was not obvious from the
code whether ->task_list was for a wait-queue head or a wait-queue entry.

Furthermore, there's a number of wait-queue users where the lists are
not for 'tasks' but other entities (poll tables, etc.), in which case
the 'task_list' name is actively confusing.

To clear this all up, name the wait-queue head and entry list structure
fields unambiguously:

	struct wait_queue_head::task_list	=> ::head
	struct wait_queue_entry::task_list	=> ::entry

For example, this code:

	rqw->wait.task_list.next != &wait->task_list

... is was pretty unclear (to me) what it's doing, while now it's written this way:

	rqw->wait.head.next != &wait->entry

... which makes it pretty clear that we are iterating a list until we see the head.

Other examples are:

	list_for_each_entry_safe(pos, next, &x->task_list, task_list) {
	list_for_each_entry(wq, &fence->wait.task_list, task_list) {

... where it's unclear (to me) what we are iterating, and during review it's
hard to tell whether it's trying to walk a wait-queue entry (which would be
a bug), while now it's written as:

	list_for_each_entry_safe(pos, next, &x->head, entry) {
	list_for_each_entry(wq, &fence->wait.head, entry) {

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 10 insertions, 10 deletions

diff --git a/include/linux/wait.h b/include/linux/wait.h
index 629489746f8a..b289c96151ee 100644
--- a/include/linux/wait.h
+++ b/include/linux/wait.h
@@ -26,12 +26,12 @@ struct wait_queue_entry {
 	unsigned int		flags;
 	void			*private;
 	wait_queue_func_t	func;
-	struct list_head	task_list;
+	struct list_head	entry;
 };
 
 struct wait_queue_head {
 	spinlock_t		lock;
-	struct list_head	task_list;
+	struct list_head	head;
 };
 typedef struct wait_queue_head wait_queue_head_t;
 
@@ -44,14 +44,14 @@ struct task_struct;
 #define __WAITQUEUE_INITIALIZER(name, tsk) {					\
 	.private	= tsk,							\
 	.func		= default_wake_function,				\
-	.task_list	= { NULL, NULL } }
+	.entry		= { NULL, NULL } }
 
 #define DECLARE_WAITQUEUE(name, tsk)						\
 	struct wait_queue_entry name = __WAITQUEUE_INITIALIZER(name, tsk)
 
 #define __WAIT_QUEUE_HEAD_INITIALIZER(name) {					\
 	.lock		= __SPIN_LOCK_UNLOCKED(name.lock),			\
-	.task_list	= { &(name).task_list, &(name).task_list } }
+	.head		= { &(name).head, &(name).head } }
 
 #define DECLARE_WAIT_QUEUE_HEAD(name) \
 	struct wait_queue_head name = __WAIT_QUEUE_HEAD_INITIALIZER(name)
@@ -121,7 +121,7 @@ init_waitqueue_func_entry(struct wait_queue_entry *wq_entry, wait_queue_func_t f
  */
 static inline int waitqueue_active(struct wait_queue_head *wq_head)
 {
-	return !list_empty(&wq_head->task_list);
+	return !list_empty(&wq_head->head);
 }
 
 /**
@@ -151,7 +151,7 @@ extern void remove_wait_queue(struct wait_queue_head *wq_head, struct wait_queue
 
 static inline void __add_wait_queue(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry)
 {
-	list_add(&wq_entry->task_list, &wq_head->task_list);
+	list_add(&wq_entry->entry, &wq_head->head);
 }
 
 /*
@@ -166,7 +166,7 @@ __add_wait_queue_exclusive(struct wait_queue_head *wq_head, struct wait_queue_en
 
 static inline void __add_wait_queue_entry_tail(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry)
 {
-	list_add_tail(&wq_entry->task_list, &wq_head->task_list);
+	list_add_tail(&wq_entry->entry, &wq_head->head);
 }
 
 static inline void
@@ -179,7 +179,7 @@ __add_wait_queue_entry_tail_exclusive(struct wait_queue_head *wq_head, struct wa
 static inline void
 __remove_wait_queue(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry)
 {
-	list_del(&wq_entry->task_list);
+	list_del(&wq_entry->entry);
 }
 
 void __wake_up(struct wait_queue_head *wq_head, unsigned int mode, int nr, void *key);
@@ -952,7 +952,7 @@ int autoremove_wake_function(struct wait_queue_entry *wq_entry, unsigned mode, i
 	struct wait_queue_entry name = {					\
 		.private	= current,					\
 		.func		= function,					\
-		.task_list	= LIST_HEAD_INIT((name).task_list),		\
+		.entry		= LIST_HEAD_INIT((name).entry),			\
 	}
 
 #define DEFINE_WAIT(name) DEFINE_WAIT_FUNC(name, autoremove_wake_function)
@@ -961,7 +961,7 @@ int autoremove_wake_function(struct wait_queue_entry *wq_entry, unsigned mode, i
 	do {									\
 		(wait)->private = current;					\
 		(wait)->func = autoremove_wake_function;			\
-		INIT_LIST_HEAD(&(wait)->task_list);				\
+		INIT_LIST_HEAD(&(wait)->entry);					\
 		(wait)->flags = 0;						\
 	} while (0)