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>
diff --git a/drivers/gpu/drm/i915/i915_sw_fence.c b/drivers/gpu/drm/i915/i915_sw_fence.c
index 8669bfa..380de43 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);