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

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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>
This commit is contained in:
Ingo Molnar 2017-06-20 12:06:46 +02:00
parent 5822a454d6
commit 2055da9738
18 changed files with 66 additions and 68 deletions
Download patch file Download diff file Expand all files Collapse all files

8
fs/orangefs/orangefs-bufmap.c
View file

@ -46,7 +46,7 @@ static void run_down(struct slot_map *m)
spin_lock(&m->q.lock);
if (m->c != -1) {
for (;;) {
if (likely(list_empty(&wait.task_list)))
if (likely(list_empty(&wait.entry)))
__add_wait_queue_entry_tail(&m->q, &wait);
set_current_state(TASK_UNINTERRUPTIBLE);
@ -84,7 +84,7 @@ static int wait_for_free(struct slot_map *m)
do {
long n = left, t;
if (likely(list_empty(&wait.task_list)))
if (likely(list_empty(&wait.entry)))
__add_wait_queue_entry_tail_exclusive(&m->q, &wait);
set_current_state(TASK_INTERRUPTIBLE);
@ -108,8 +108,8 @@ static int wait_for_free(struct slot_map *m)
left = -EINTR;
} while (left > 0);
if (!list_empty(&wait.task_list))
list_del(&wait.task_list);
if (!list_empty(&wait.entry))
list_del(&wait.entry);
else if (left <= 0 && waitqueue_active(&m->q))
__wake_up_locked_key(&m->q, TASK_INTERRUPTIBLE, NULL);
__set_current_state(TASK_RUNNING);