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, 4 insertions, 4 deletions

diff --git a/block/kyber-iosched.c b/block/kyber-iosched.c
index b95d6bd714c0..9bf1484365b2 100644
--- a/block/kyber-iosched.c
+++ b/block/kyber-iosched.c
@@ -385,7 +385,7 @@ static int kyber_init_hctx(struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
 
         for (i = 0; i < KYBER_NUM_DOMAINS; i++) {
                 INIT_LIST_HEAD(&khd->rqs[i]);
-                INIT_LIST_HEAD(&khd->domain_wait[i].task_list);
+                INIT_LIST_HEAD(&khd->domain_wait[i].entry);
                 atomic_set(&khd->wait_index[i], 0);
         }
 
@@ -512,7 +512,7 @@ static int kyber_domain_wake(wait_queue_entry_t *wait, unsigned mode, int flags,
 {
         struct blk_mq_hw_ctx *hctx = READ_ONCE(wait->private);
 
-        list_del_init(&wait->task_list);
+        list_del_init(&wait->entry);
         blk_mq_run_hw_queue(hctx, true);
         return 1;
 }
@@ -536,7 +536,7 @@ static int kyber_get_domain_token(struct kyber_queue_data *kqd,
          * run when one becomes available. Note that this is serialized on
          * khd->lock, but we still need to be careful about the waker.
          */
-        if (list_empty_careful(&wait->task_list)) {
+        if (list_empty_careful(&wait->entry)) {
                 init_waitqueue_func_entry(wait, kyber_domain_wake);
                 wait->private = hctx;
                 ws = sbq_wait_ptr(domain_tokens,
@@ -736,7 +736,7 @@ static int kyber_##name##_waiting_show(void *data, struct seq_file *m)	\
         struct kyber_hctx_data *khd = hctx->sched_data;                 \
         wait_queue_entry_t *wait = &khd->domain_wait[domain];           \
                                                                         \
-        seq_printf(m, "%d\n", !list_empty_careful(&wait->task_list));   \
+        seq_printf(m, "%d\n", !list_empty_careful(&wait->entry));       \
         return 0;                                                       \
 }
 KYBER_DEBUGFS_DOMAIN_ATTRS(KYBER_READ, read)