locking/ww_mutex: Abstract out the waiter iteration

[platform/kernel/linux-rpi.git] / kernel / locking / ww_mutex.h

diff --git a/kernel/locking/ww_mutex.h b/kernel/locking/ww_mutex.h
index 6a98f3b..1cd178c 100644 (file)
--- a/kernel/locking/ww_mutex.h
+++ b/kernel/locking/ww_mutex.h
@@ -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;