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, 11 deletions

diff --git a/drivers/gpu/drm/i915/i915_sw_fence.c b/drivers/gpu/drm/i915/i915_sw_fence.c
index 8669bfa33064..380de4360b8a 100644
--- a/drivers/gpu/drm/i915/i915_sw_fence.c
+++ b/drivers/gpu/drm/i915/i915_sw_fence.c
@@ -160,31 +160,30 @@ static void __i915_sw_fence_wake_up_all(struct i915_sw_fence *fence,
 
 	/*
 	 * To prevent unbounded recursion as we traverse the graph of
-	 * i915_sw_fences, we move the task_list from this, the next ready
-	 * fence, to the tail of the original fence's task_list
+	 * i915_sw_fences, we move the entry list from this, the next ready
+	 * fence, to the tail of the original fence's entry list
 	 * (and so added to the list to be woken).
 	 */
 
 	spin_lock_irqsave_nested(&x->lock, flags, 1 + !!continuation);
 	if (continuation) {
-		list_for_each_entry_safe(pos, next, &x->task_list, task_list) {
+		list_for_each_entry_safe(pos, next, &x->head, entry) {
 			if (pos->func == autoremove_wake_function)
 				pos->func(pos, TASK_NORMAL, 0, continuation);
 			else
-				list_move_tail(&pos->task_list, continuation);
+				list_move_tail(&pos->entry, continuation);
 		}
 	} else {
 		LIST_HEAD(extra);
 
 		do {
-			list_for_each_entry_safe(pos, next,
-						 &x->task_list, task_list)
+			list_for_each_entry_safe(pos, next, &x->head, entry)
 				pos->func(pos, TASK_NORMAL, 0, &extra);
 
 			if (list_empty(&extra))
 				break;
 
-			list_splice_tail_init(&extra, &x->task_list);
+			list_splice_tail_init(&extra, &x->head);
 		} while (1);
 	}
 	spin_unlock_irqrestore(&x->lock, flags);
@@ -256,7 +255,7 @@ void i915_sw_fence_commit(struct i915_sw_fence *fence)
 
 static int i915_sw_fence_wake(wait_queue_entry_t *wq, unsigned mode, int flags, void *key)
 {
-	list_del(&wq->task_list);
+	list_del(&wq->entry);
 	__i915_sw_fence_complete(wq->private, key);
 	i915_sw_fence_put(wq->private);
 	if (wq->flags & I915_SW_FENCE_FLAG_ALLOC)
@@ -275,7 +274,7 @@ static bool __i915_sw_fence_check_if_after(struct i915_sw_fence *fence,
 	if (fence == signaler)
 		return true;
 
-	list_for_each_entry(wq, &fence->wait.task_list, task_list) {
+	list_for_each_entry(wq, &fence->wait.head, entry) {
 		if (wq->func != i915_sw_fence_wake)
 			continue;
 
@@ -293,7 +292,7 @@ static void __i915_sw_fence_clear_checked_bit(struct i915_sw_fence *fence)
 	if (!__test_and_clear_bit(I915_SW_FENCE_CHECKED_BIT, &fence->flags))
 		return;
 
-	list_for_each_entry(wq, &fence->wait.task_list, task_list) {
+	list_for_each_entry(wq, &fence->wait.head, entry) {
 		if (wq->func != i915_sw_fence_wake)
 			continue;
 
@@ -350,7 +349,7 @@ static int __i915_sw_fence_await_sw_fence(struct i915_sw_fence *fence,
 		pending |= I915_SW_FENCE_FLAG_ALLOC;
 	}
 
-	INIT_LIST_HEAD(&wq->task_list);
+	INIT_LIST_HEAD(&wq->entry);
 	wq->flags = pending;
 	wq->func = i915_sw_fence_wake;
 	wq->private = i915_sw_fence_get(fence);