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authorIngo Molnar <mingo@kernel.org>2017-03-05 11:35:27 +0100
committerIngo Molnar <mingo@kernel.org>2017-06-20 12:18:29 +0200
commit76c85ddc4695bb7b8209bfeff11f5156088f9197 (patch)
treebd6772616e1c304097cd6d11f3654bc01c4a9127 /kernel/sched/wait.c
parent2141713616c652aeabf2dd5c1e89bc601c4fed6a (diff)
sched/wait: Standardize wait_bit_queue naming
So wait-bit-queue head variables are often named: struct wait_bit_queue *q ... which is a bit ambiguous and super confusing, because they clearly suggest wait-queue head semantics and behavior (they rhyme with the old wait_queue_t *q naming), while they are extended wait-queue _entries_, not heads! They are misnomers in two ways: - the 'wait_bit_queue' leaves open the question of whether it's an entry or a head - the 'q' parameter and local variable naming falsely implies that it's a 'queue' - while it's an entry. This resulted in sometimes confusing cases such as: finish_wait(wq, &q->wait); where the 'q' is not a wait-queue head, but a wait-bit-queue entry. So improve this all by standardizing wait-bit-queue nomenclature similar to wait-queue head naming: struct wait_bit_queue => struct wait_bit_queue_entry q => wbq_entry Which makes it all a much clearer: struct wait_bit_queue_entry *wbq_entry ... and turns the former confusing piece of code into: finish_wait(wq_head, &wbq_entry->wq_entry; which IMHO makes it apparently clear what we are doing, without having to analyze the context of the code: we are adding a wait-queue entry to a regular wait-queue head, which entry is embedded in a wait-bit-queue entry. I'm not a big fan of acronyms, but repeating wait_bit_queue_entry in field and local variable names is too long, so Hopefully it's clear enough that 'wq_' prefixes stand for wait-queues, while 'wbq_' prefixes stand for wait-bit-queues. 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>
Diffstat (limited to 'kernel/sched/wait.c')
-rw-r--r--kernel/sched/wait.c41
1 files changed, 20 insertions, 21 deletions
diff --git a/kernel/sched/wait.c b/kernel/sched/wait.c
index f1ba0625b8be..95e6d3820cba 100644
--- a/kernel/sched/wait.c
+++ b/kernel/sched/wait.c
@@ -394,8 +394,7 @@ EXPORT_SYMBOL(woken_wake_function);
int wake_bit_function(struct wait_queue_entry *wq_entry, unsigned mode, int sync, void *arg)
{
struct wait_bit_key *key = arg;
- struct wait_bit_queue *wait_bit
- = container_of(wq_entry, struct wait_bit_queue, wq_entry);
+ struct wait_bit_queue_entry *wait_bit = container_of(wq_entry, struct wait_bit_queue_entry, wq_entry);
if (wait_bit->key.flags != key->flags ||
wait_bit->key.bit_nr != key->bit_nr ||
@@ -412,17 +411,17 @@ EXPORT_SYMBOL(wake_bit_function);
* permitted return codes. Nonzero return codes halt waiting and return.
*/
int __sched
-__wait_on_bit(struct wait_queue_head *wq_head, struct wait_bit_queue *q,
+__wait_on_bit(struct wait_queue_head *wq_head, struct wait_bit_queue_entry *wbq_entry,
wait_bit_action_f *action, unsigned mode)
{
int ret = 0;
do {
- prepare_to_wait(wq_head, &q->wq_entry, mode);
- if (test_bit(q->key.bit_nr, q->key.flags))
- ret = (*action)(&q->key, mode);
- } while (test_bit(q->key.bit_nr, q->key.flags) && !ret);
- finish_wait(wq_head, &q->wq_entry);
+ prepare_to_wait(wq_head, &wbq_entry->wq_entry, mode);
+ if (test_bit(wbq_entry->key.bit_nr, wbq_entry->key.flags))
+ ret = (*action)(&wbq_entry->key, mode);
+ } while (test_bit(wbq_entry->key.bit_nr, wbq_entry->key.flags) && !ret);
+ finish_wait(wq_head, &wbq_entry->wq_entry);
return ret;
}
EXPORT_SYMBOL(__wait_on_bit);
@@ -450,15 +449,15 @@ int __sched out_of_line_wait_on_bit_timeout(
EXPORT_SYMBOL_GPL(out_of_line_wait_on_bit_timeout);
int __sched
-__wait_on_bit_lock(struct wait_queue_head *wq_head, struct wait_bit_queue *q,
+__wait_on_bit_lock(struct wait_queue_head *wq_head, struct wait_bit_queue_entry *wbq_entry,
wait_bit_action_f *action, unsigned mode)
{
int ret = 0;
for (;;) {
- prepare_to_wait_exclusive(wq_head, &q->wq_entry, mode);
- if (test_bit(q->key.bit_nr, q->key.flags)) {
- ret = action(&q->key, mode);
+ prepare_to_wait_exclusive(wq_head, &wbq_entry->wq_entry, mode);
+ if (test_bit(wbq_entry->key.bit_nr, wbq_entry->key.flags)) {
+ ret = action(&wbq_entry->key, mode);
/*
* See the comment in prepare_to_wait_event().
* finish_wait() does not necessarily takes wwq_head->lock,
@@ -466,11 +465,11 @@ __wait_on_bit_lock(struct wait_queue_head *wq_head, struct wait_bit_queue *q,
* smp_mb__after_atomic() before wake_up_page().
*/
if (ret)
- finish_wait(wq_head, &q->wq_entry);
+ finish_wait(wq_head, &wbq_entry->wq_entry);
}
- if (!test_and_set_bit(q->key.bit_nr, q->key.flags)) {
+ if (!test_and_set_bit(wbq_entry->key.bit_nr, wbq_entry->key.flags)) {
if (!ret)
- finish_wait(wq_head, &q->wq_entry);
+ finish_wait(wq_head, &wbq_entry->wq_entry);
return 0;
} else if (ret) {
return ret;
@@ -538,7 +537,7 @@ static int wake_atomic_t_function(struct wait_queue_entry *wq_entry, unsigned mo
void *arg)
{
struct wait_bit_key *key = arg;
- struct wait_bit_queue *wait_bit = container_of(wq_entry, struct wait_bit_queue, wq_entry);
+ struct wait_bit_queue_entry *wait_bit = container_of(wq_entry, struct wait_bit_queue_entry, wq_entry);
atomic_t *val = key->flags;
if (wait_bit->key.flags != key->flags ||
@@ -554,25 +553,25 @@ static int wake_atomic_t_function(struct wait_queue_entry *wq_entry, unsigned mo
* return codes halt waiting and return.
*/
static __sched
-int __wait_on_atomic_t(struct wait_queue_head *wq_head, struct wait_bit_queue *q,
+int __wait_on_atomic_t(struct wait_queue_head *wq_head, struct wait_bit_queue_entry *wbq_entry,
int (*action)(atomic_t *), unsigned mode)
{
atomic_t *val;
int ret = 0;
do {
- prepare_to_wait(wq_head, &q->wq_entry, mode);
- val = q->key.flags;
+ prepare_to_wait(wq_head, &wbq_entry->wq_entry, mode);
+ val = wbq_entry->key.flags;
if (atomic_read(val) == 0)
break;
ret = (*action)(val);
} while (!ret && atomic_read(val) != 0);
- finish_wait(wq_head, &q->wq_entry);
+ finish_wait(wq_head, &wbq_entry->wq_entry);
return ret;
}
#define DEFINE_WAIT_ATOMIC_T(name, p) \
- struct wait_bit_queue name = { \
+ struct wait_bit_queue_entry name = { \
.key = __WAIT_ATOMIC_T_KEY_INITIALIZER(p), \
.wq_entry = { \
.private = current, \