1 files changed, 18 insertions, 23 deletions

diff --git a/kernel/mutex.c b/kernel/mutex.c
index 7ff48c55a98b..386ad5da47a5 100644
--- a/kernel/mutex.c
+++ b/kernel/mutex.c
@@ -463,7 +463,7 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
                          * performed the optimistic spinning cannot be done.
                          */
                         if (ACCESS_ONCE(ww->ctx))
-                                break;
+                                goto slowpath;
                 }
 
                 /*
@@ -474,7 +474,7 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
                 owner = ACCESS_ONCE(lock->owner);
                 if (owner && !mutex_spin_on_owner(lock, owner)) {
                         mspin_unlock(MLOCK(lock), &node);
-                        break;
+                        goto slowpath;
                 }
 
                 if ((atomic_read(&lock->count) == 1) &&
@@ -489,8 +489,7 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
 
                         mutex_set_owner(lock);
                         mspin_unlock(MLOCK(lock), &node);
-                        preempt_enable();
-                        return 0;
+                        goto done;
                 }
                 mspin_unlock(MLOCK(lock), &node);
 
@@ -501,7 +500,7 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
                  * the owner complete.
                  */
                 if (!owner && (need_resched() || rt_task(task)))
-                        break;
+                        goto slowpath;
 
                 /*
                  * The cpu_relax() call is a compiler barrier which forces
@@ -515,6 +514,10 @@ slowpath:
 #endif
         spin_lock_mutex(&lock->wait_lock, flags);
 
+        /* once more, can we acquire the lock? */
+        if (MUTEX_SHOW_NO_WAITER(lock) && (atomic_xchg(&lock->count, 0) == 1))
+                goto skip_wait;
+
         debug_mutex_lock_common(lock, &waiter);
         debug_mutex_add_waiter(lock, &waiter, task_thread_info(task));
 
@@ -522,9 +525,6 @@ slowpath:
         list_add_tail(&waiter.list, &lock->wait_list);
         waiter.task = task;
 
-        if (MUTEX_SHOW_NO_WAITER(lock) && (atomic_xchg(&lock->count, -1) == 1))
-                goto done;
-
         lock_contended(&lock->dep_map, ip);
 
         for (;;) {
@@ -538,7 +538,7 @@ slowpath:
                  * other waiters:
                  */
                 if (MUTEX_SHOW_NO_WAITER(lock) &&
-                   (atomic_xchg(&lock->count, -1) == 1))
+                    (atomic_xchg(&lock->count, -1) == 1))
                         break;
 
                 /*
@@ -563,24 +563,25 @@ slowpath:
                 schedule_preempt_disabled();
                 spin_lock_mutex(&lock->wait_lock, flags);
         }
+        mutex_remove_waiter(lock, &waiter, current_thread_info());
+        /* set it to 0 if there are no waiters left: */
+        if (likely(list_empty(&lock->wait_list)))
+                atomic_set(&lock->count, 0);
+        debug_mutex_free_waiter(&waiter);
 
-done:
+skip_wait:
+        /* got the lock - cleanup and rejoice! */
         lock_acquired(&lock->dep_map, ip);
-        /* got the lock - rejoice! */
-        mutex_remove_waiter(lock, &waiter, current_thread_info());
         mutex_set_owner(lock);
 
         if (!__builtin_constant_p(ww_ctx == NULL)) {
-                struct ww_mutex *ww = container_of(lock,
-                                                      struct ww_mutex,
-                                                      base);
+                struct ww_mutex *ww = container_of(lock, struct ww_mutex, base);
                 struct mutex_waiter *cur;
 
                 /*
                  * This branch gets optimized out for the common case,
                  * and is only important for ww_mutex_lock.
                  */
-
                 ww_mutex_lock_acquired(ww, ww_ctx);
                 ww->ctx = ww_ctx;
 
@@ -594,15 +595,9 @@ done:
                 }
         }
 
-        /* set it to 0 if there are no waiters left: */
-        if (likely(list_empty(&lock->wait_list)))
-                atomic_set(&lock->count, 0);
-
         spin_unlock_mutex(&lock->wait_lock, flags);
-
-        debug_mutex_free_waiter(&waiter);
+done:
         preempt_enable();
-
         return 0;
 
 err: