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sched/wait: Standardize internal naming of wait-queue entries

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So the various wait-queue entry variables in include/linux/wait.h
and kernel/sched/wait.c are named in a colorfully inconsistent
way:

	wait_queue_entry_t *wait
	wait_queue_entry_t *__wait	(even in plain C code!)
	wait_queue_entry_t *q		(!)
	wait_queue_entry_t *new		(making anyone who knows C++ cringe)
	wait_queue_entry_t *old

I think part of the reason for the inconsistency is the constant
apparent confusion about what a wait queue 'head' versus 'entry' is.

( Some of the documentation talks about a 'wait descriptor', which is
  the wait-queue entry itself - further adding to the confusion. )

The most common name is 'wait', but that in itself is somewhat
ambiguous as well, as it does not really make it clear whether
it's a wait-queue entry or head.

To improve all this name the wait-queue entry structure parameters
and variables consistently and push through this naming into all
the wait.h and wait.c code:

	struct wait_queue_entry *wq_entry

The 'wq_' prefix makes it easy to grep for, and we also use the
opportunity to move away from the typedef to a plain 'struct' naming:
in the kernel we typically reserve typedefs for cases where a
C structure is really small and somewhat opaque - such as pte_t.

wait-queue entries are neither small nor opaque, so use the more
standard 'struct xxx_entry' list management code nomenclature instead.

( We don't touch external users, and we preserve the typedef as well
  for actual wait-queue users, to reduce unnecessary churn. )

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 12:18:27 +02:00
parent ac6424b981
commit 50816c4899
2 changed files with 91 additions and 91 deletions
Download Patch File Download Diff File Expand all files Collapse all files
kernel/sched/wait.c
+49 -49
View File
@@ -21,34 +21,34 @@ void __init_waitqueue_head(wait_queue_head_t *q, const char *name, struct lock_c
EXPORT_SYMBOL(__init_waitqueue_head);
void add_wait_queue(wait_queue_head_t *q, wait_queue_entry_t *wait)
void add_wait_queue(wait_queue_head_t *q, struct wait_queue_entry *wq_entry)
{
unsigned long flags;
wait->flags &= ~WQ_FLAG_EXCLUSIVE;
wq_entry->flags &= ~WQ_FLAG_EXCLUSIVE;
spin_lock_irqsave(&q->lock, flags);
__add_wait_queue(q, wait);
__add_wait_queue_entry_tail(q, wq_entry);
spin_unlock_irqrestore(&q->lock, flags);
}
EXPORT_SYMBOL(add_wait_queue);
void add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_entry_t *wait)
void add_wait_queue_exclusive(wait_queue_head_t *q, struct wait_queue_entry *wq_entry)
{
unsigned long flags;
wait->flags |= WQ_FLAG_EXCLUSIVE;
wq_entry->flags |= WQ_FLAG_EXCLUSIVE;
spin_lock_irqsave(&q->lock, flags);
__add_wait_queue_entry_tail(q, wait);
__add_wait_queue_entry_tail(q, wq_entry);
spin_unlock_irqrestore(&q->lock, flags);
}
EXPORT_SYMBOL(add_wait_queue_exclusive);
void remove_wait_queue(wait_queue_head_t *q, wait_queue_entry_t *wait)
void remove_wait_queue(wait_queue_head_t *q, struct wait_queue_entry *wq_entry)
{
unsigned long flags;
spin_lock_irqsave(&q->lock, flags);
__remove_wait_queue(q, wait);
__remove_wait_queue(q, wq_entry);
spin_unlock_irqrestore(&q->lock, flags);
}
EXPORT_SYMBOL(remove_wait_queue);
@@ -170,43 +170,43 @@ EXPORT_SYMBOL_GPL(__wake_up_sync); /* For internal use only */
* loads to move into the critical region).
*/
void
prepare_to_wait(wait_queue_head_t *q, wait_queue_entry_t *wait, int state)
prepare_to_wait(wait_queue_head_t *q, struct wait_queue_entry *wq_entry, int state)
{
unsigned long flags;
wait->flags &= ~WQ_FLAG_EXCLUSIVE;
wq_entry->flags &= ~WQ_FLAG_EXCLUSIVE;
spin_lock_irqsave(&q->lock, flags);
if (list_empty(&wait->task_list))
__add_wait_queue(q, wait);
if (list_empty(&wq_entry->task_list))
__add_wait_queue(q, wq_entry);
set_current_state(state);
spin_unlock_irqrestore(&q->lock, flags);
}
EXPORT_SYMBOL(prepare_to_wait);
void
prepare_to_wait_exclusive(wait_queue_head_t *q, wait_queue_entry_t *wait, int state)
prepare_to_wait_exclusive(wait_queue_head_t *q, struct wait_queue_entry *wq_entry, int state)
{
unsigned long flags;
wait->flags |= WQ_FLAG_EXCLUSIVE;
wq_entry->flags |= WQ_FLAG_EXCLUSIVE;
spin_lock_irqsave(&q->lock, flags);
if (list_empty(&wait->task_list))
__add_wait_queue_entry_tail(q, wait);
if (list_empty(&wq_entry->task_list))
__add_wait_queue_entry_tail(q, wq_entry);
set_current_state(state);
spin_unlock_irqrestore(&q->lock, flags);
}
EXPORT_SYMBOL(prepare_to_wait_exclusive);
void init_wait_entry(wait_queue_entry_t *wait, int flags)
void init_wait_entry(struct wait_queue_entry *wq_entry, int flags)
{
wait->flags = flags;
wait->private = current;
wait->func = autoremove_wake_function;
INIT_LIST_HEAD(&wait->task_list);
wq_entry->flags = flags;
wq_entry->private = current;
wq_entry->func = autoremove_wake_function;
INIT_LIST_HEAD(&wq_entry->task_list);
}
EXPORT_SYMBOL(init_wait_entry);
long prepare_to_wait_event(wait_queue_head_t *q, wait_queue_entry_t *wait, int state)
long prepare_to_wait_event(wait_queue_head_t *q, struct wait_queue_entry *wq_entry, int state)
{
unsigned long flags;
long ret = 0;
@@ -225,14 +225,14 @@ long prepare_to_wait_event(wait_queue_head_t *q, wait_queue_entry_t *wait, int s
* can't see us, it should wake up another exclusive waiter if
* we fail.
*/
list_del_init(&wait->task_list);
list_del_init(&wq_entry->task_list);
ret = -ERESTARTSYS;
} else {
if (list_empty(&wait->task_list)) {
if (wait->flags & WQ_FLAG_EXCLUSIVE)
__add_wait_queue_entry_tail(q, wait);
if (list_empty(&wq_entry->task_list)) {
if (wq_entry->flags & WQ_FLAG_EXCLUSIVE)
__add_wait_queue_entry_tail(q, wq_entry);
else
__add_wait_queue(q, wait);
__add_wait_queue(q, wq_entry);
}
set_current_state(state);
}
@@ -284,13 +284,13 @@ EXPORT_SYMBOL(do_wait_intr_irq);
/**
* finish_wait - clean up after waiting in a queue
* @q: waitqueue waited on
* @wait: wait descriptor
* @wq_entry: wait descriptor
*
* Sets current thread back to running state and removes
* the wait descriptor from the given waitqueue if still
* queued.
*/
void finish_wait(wait_queue_head_t *q, wait_queue_entry_t *wait)
void finish_wait(wait_queue_head_t *q, struct wait_queue_entry *wq_entry)
{
unsigned long flags;
@@ -308,20 +308,20 @@ void finish_wait(wait_queue_head_t *q, wait_queue_entry_t *wait)
* have _one_ other CPU that looks at or modifies
* the list).
*/
if (!list_empty_careful(&wait->task_list)) {
if (!list_empty_careful(&wq_entry->task_list)) {
spin_lock_irqsave(&q->lock, flags);
list_del_init(&wait->task_list);
list_del_init(&wq_entry->task_list);
spin_unlock_irqrestore(&q->lock, flags);
}
}
EXPORT_SYMBOL(finish_wait);
int autoremove_wake_function(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
int autoremove_wake_function(struct wait_queue_entry *wq_entry, unsigned mode, int sync, void *key)
{
int ret = default_wake_function(wait, mode, sync, key);
int ret = default_wake_function(wq_entry, mode, sync, key);
if (ret)
list_del_init(&wait->task_list);
list_del_init(&wq_entry->task_list);
return ret;
}
EXPORT_SYMBOL(autoremove_wake_function);
@@ -341,17 +341,17 @@ static inline bool is_kthread_should_stop(void)
*
* p->state = mode; condition = true;
* smp_mb(); // A smp_wmb(); // C
* if (!wait->flags & WQ_FLAG_WOKEN) wait->flags |= WQ_FLAG_WOKEN;
* if (!wq_entry->flags & WQ_FLAG_WOKEN) wq_entry->flags |= WQ_FLAG_WOKEN;
* schedule() try_to_wake_up();
* p->state = TASK_RUNNING; ~~~~~~~~~~~~~~~~~~
* wait->flags &= ~WQ_FLAG_WOKEN; condition = true;
* wq_entry->flags &= ~WQ_FLAG_WOKEN; condition = true;
* smp_mb() // B smp_wmb(); // C
* wait->flags |= WQ_FLAG_WOKEN;
* wq_entry->flags |= WQ_FLAG_WOKEN;
* }
* remove_wait_queue(&wq, &wait);
*
*/
long wait_woken(wait_queue_entry_t *wait, unsigned mode, long timeout)
long wait_woken(struct wait_queue_entry *wq_entry, unsigned mode, long timeout)
{
set_current_state(mode); /* A */
/*
@@ -359,7 +359,7 @@ long wait_woken(wait_queue_entry_t *wait, unsigned mode, long timeout)
* woken_wake_function() such that if we observe WQ_FLAG_WOKEN we must
* also observe all state before the wakeup.
*/
if (!(wait->flags & WQ_FLAG_WOKEN) && !is_kthread_should_stop())
if (!(wq_entry->flags & WQ_FLAG_WOKEN) && !is_kthread_should_stop())
timeout = schedule_timeout(timeout);
__set_current_state(TASK_RUNNING);
@@ -369,13 +369,13 @@ long wait_woken(wait_queue_entry_t *wait, unsigned mode, long timeout)
* condition being true _OR_ WQ_FLAG_WOKEN such that we will not miss
* an event.
*/
smp_store_mb(wait->flags, wait->flags & ~WQ_FLAG_WOKEN); /* B */
smp_store_mb(wq_entry->flags, wq_entry->flags & ~WQ_FLAG_WOKEN); /* B */
return timeout;
}
EXPORT_SYMBOL(wait_woken);
int woken_wake_function(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
int woken_wake_function(struct wait_queue_entry *wq_entry, unsigned mode, int sync, void *key)
{
/*
* Although this function is called under waitqueue lock, LOCK
@@ -385,24 +385,24 @@ int woken_wake_function(wait_queue_entry_t *wait, unsigned mode, int sync, void
* and is paired with smp_store_mb() in wait_woken().
*/
smp_wmb(); /* C */
wait->flags |= WQ_FLAG_WOKEN;
wq_entry->flags |= WQ_FLAG_WOKEN;
return default_wake_function(wait, mode, sync, key);
return default_wake_function(wq_entry, mode, sync, key);
}
EXPORT_SYMBOL(woken_wake_function);
int wake_bit_function(wait_queue_entry_t *wait, unsigned mode, int sync, void *arg)
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(wait, struct wait_bit_queue, wait);
= container_of(wq_entry, struct wait_bit_queue, wait);
if (wait_bit->key.flags != key->flags ||
wait_bit->key.bit_nr != key->bit_nr ||
test_bit(key->bit_nr, key->flags))
return 0;
else
return autoremove_wake_function(wait, mode, sync, key);
return autoremove_wake_function(wq_entry, mode, sync, key);
}
EXPORT_SYMBOL(wake_bit_function);
@@ -534,19 +534,19 @@ static inline wait_queue_head_t *atomic_t_waitqueue(atomic_t *p)
return bit_waitqueue(p, 0);
}
static int wake_atomic_t_function(wait_queue_entry_t *wait, unsigned mode, int sync,
static int wake_atomic_t_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(wait, struct wait_bit_queue, wait);
= container_of(wq_entry, struct wait_bit_queue, wait);
atomic_t *val = key->flags;
if (wait_bit->key.flags != key->flags ||
wait_bit->key.bit_nr != key->bit_nr ||
atomic_read(val) != 0)
return 0;
return autoremove_wake_function(wait, mode, sync, key);
return autoremove_wake_function(wq_entry, mode, sync, key);
}
/*