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, 12 insertions, 12 deletions

diff --git a/kernel/sched/wait.c b/kernel/sched/wait.c
index 6bcd7c3c45019..17f11c6b0a9f7 100644
--- a/kernel/sched/wait.c
+++ b/kernel/sched/wait.c
@@ -16,7 +16,7 @@ void __init_waitqueue_head(struct wait_queue_head *wq_head, const char *name, st
 {
 	spin_lock_init(&wq_head->lock);
 	lockdep_set_class_and_name(&wq_head->lock, key, name);
-	INIT_LIST_HEAD(&wq_head->task_list);
+	INIT_LIST_HEAD(&wq_head->head);
 }
 
 EXPORT_SYMBOL(__init_waitqueue_head);
@@ -68,7 +68,7 @@ static void __wake_up_common(struct wait_queue_head *wq_head, unsigned int mode,
 {
 	wait_queue_entry_t *curr, *next;
 
-	list_for_each_entry_safe(curr, next, &wq_head->task_list, task_list) {
+	list_for_each_entry_safe(curr, next, &wq_head->head, entry) {
 		unsigned flags = curr->flags;
 
 		if (curr->func(curr, mode, wake_flags, key) &&
@@ -176,7 +176,7 @@ prepare_to_wait(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_ent
 
 	wq_entry->flags &= ~WQ_FLAG_EXCLUSIVE;
 	spin_lock_irqsave(&wq_head->lock, flags);
-	if (list_empty(&wq_entry->task_list))
+	if (list_empty(&wq_entry->entry))
 		__add_wait_queue(wq_head, wq_entry);
 	set_current_state(state);
 	spin_unlock_irqrestore(&wq_head->lock, flags);
@@ -190,7 +190,7 @@ prepare_to_wait_exclusive(struct wait_queue_head *wq_head, struct wait_queue_ent
 
 	wq_entry->flags |= WQ_FLAG_EXCLUSIVE;
 	spin_lock_irqsave(&wq_head->lock, flags);
-	if (list_empty(&wq_entry->task_list))
+	if (list_empty(&wq_entry->entry))
 		__add_wait_queue_entry_tail(wq_head, wq_entry);
 	set_current_state(state);
 	spin_unlock_irqrestore(&wq_head->lock, flags);
@@ -202,7 +202,7 @@ void init_wait_entry(struct wait_queue_entry *wq_entry, int flags)
 	wq_entry->flags = flags;
 	wq_entry->private = current;
 	wq_entry->func = autoremove_wake_function;
-	INIT_LIST_HEAD(&wq_entry->task_list);
+	INIT_LIST_HEAD(&wq_entry->entry);
 }
 EXPORT_SYMBOL(init_wait_entry);
 
@@ -225,10 +225,10 @@ long prepare_to_wait_event(struct wait_queue_head *wq_head, struct wait_queue_en
 		 * can't see us, it should wake up another exclusive waiter if
 		 * we fail.
 		 */
-		list_del_init(&wq_entry->task_list);
+		list_del_init(&wq_entry->entry);
 		ret = -ERESTARTSYS;
 	} else {
-		if (list_empty(&wq_entry->task_list)) {
+		if (list_empty(&wq_entry->entry)) {
 			if (wq_entry->flags & WQ_FLAG_EXCLUSIVE)
 				__add_wait_queue_entry_tail(wq_head, wq_entry);
 			else
@@ -251,7 +251,7 @@ EXPORT_SYMBOL(prepare_to_wait_event);
  */
 int do_wait_intr(wait_queue_head_t *wq, wait_queue_entry_t *wait)
 {
-	if (likely(list_empty(&wait->task_list)))
+	if (likely(list_empty(&wait->entry)))
 		__add_wait_queue_entry_tail(wq, wait);
 
 	set_current_state(TASK_INTERRUPTIBLE);
@@ -267,7 +267,7 @@ EXPORT_SYMBOL(do_wait_intr);
 
 int do_wait_intr_irq(wait_queue_head_t *wq, wait_queue_entry_t *wait)
 {
-	if (likely(list_empty(&wait->task_list)))
+	if (likely(list_empty(&wait->entry)))
 		__add_wait_queue_entry_tail(wq, wait);
 
 	set_current_state(TASK_INTERRUPTIBLE);
@@ -308,9 +308,9 @@ void finish_wait(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_en
 	 *    have _one_ other CPU that looks at or modifies
 	 *    the list).
 	 */
-	if (!list_empty_careful(&wq_entry->task_list)) {
+	if (!list_empty_careful(&wq_entry->entry)) {
 		spin_lock_irqsave(&wq_head->lock, flags);
-		list_del_init(&wq_entry->task_list);
+		list_del_init(&wq_entry->entry);
 		spin_unlock_irqrestore(&wq_head->lock, flags);
 	}
 }
@@ -321,7 +321,7 @@ int autoremove_wake_function(struct wait_queue_entry *wq_entry, unsigned mode, i
 	int ret = default_wake_function(wq_entry, mode, sync, key);
 
 	if (ret)
-		list_del_init(&wq_entry->task_list);
+		list_del_init(&wq_entry->entry);
 	return ret;
 }
 EXPORT_SYMBOL(autoremove_wake_function);