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locking/ww_mutex: Abstract out the waiter iteration

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Split out the waiter iteration functions so they can be substituted for a
rtmutex based ww_mutex later.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210815211304.509186185@linutronix.de
This commit is contained in:
Peter Zijlstra 2021-08-15 23:28:45 +02:00 committed by Ingo Molnar
parent 5297ccb2c5
commit 23d599eb23
1 changed files with 53 additions and 4 deletions
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57
kernel/locking/ww_mutex.h
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@ -1,5 +1,49 @@
/* SPDX-License-Identifier: GPL-2.0-only */
static inline struct mutex_waiter *
__ww_waiter_first(struct mutex *lock)
{
struct mutex_waiter *w;
w = list_first_entry(&lock->wait_list, struct mutex_waiter, list);
if (list_entry_is_head(w, &lock->wait_list, list))
return NULL;
return w;
}
static inline struct mutex_waiter *
__ww_waiter_next(struct mutex *lock, struct mutex_waiter *w)
{
w = list_next_entry(w, list);
if (list_entry_is_head(w, &lock->wait_list, list))
return NULL;
return w;
}
static inline struct mutex_waiter *
__ww_waiter_prev(struct mutex *lock, struct mutex_waiter *w)
{
w = list_prev_entry(w, list);
if (list_entry_is_head(w, &lock->wait_list, list))
return NULL;
return w;
}
static inline struct mutex_waiter *
__ww_waiter_last(struct mutex *lock)
{
struct mutex_waiter *w;
w = list_last_entry(&lock->wait_list, struct mutex_waiter, list);
if (list_entry_is_head(w, &lock->wait_list, list))
return NULL;
return w;
}
/*
* Wait-Die:
* The newer transactions are killed when:
@ -161,7 +205,9 @@ __ww_mutex_check_waiters(struct mutex *lock, struct ww_acquire_ctx *ww_ctx)
lockdep_assert_held(&lock->wait_lock);
list_for_each_entry(cur, &lock->wait_list, list) {
for (cur = __ww_waiter_first(lock); cur;
cur = __ww_waiter_next(lock, cur)) {
if (!cur->ww_ctx)
continue;
@ -263,8 +309,9 @@ __ww_mutex_check_kill(struct mutex *lock, struct mutex_waiter *waiter,
* If there is a waiter in front of us that has a context, then its
* stamp is earlier than ours and we must kill ourself.
*/
cur = waiter;
list_for_each_entry_continue_reverse(cur, &lock->wait_list, list) {
for (cur = __ww_waiter_prev(lock, waiter); cur;
cur = __ww_waiter_prev(lock, cur)) {
if (!cur->ww_ctx)
continue;
@ -309,7 +356,9 @@ __ww_mutex_add_waiter(struct mutex_waiter *waiter,
* may wound the lock holder.
*/
pos = &lock->wait_list;
list_for_each_entry_reverse(cur, &lock->wait_list, list) {
for (cur = __ww_waiter_last(lock); cur;
cur = __ww_waiter_prev(lock, cur)) {
if (!cur->ww_ctx)
continue;