locking/lockdep: Factor out the find_held_lock() helper function

A simple consolidataion to factor out repeated patterns.

The behaviour should not change.

Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1486053497-9948-1-git-send-email-hooanon05g@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index a95e5d1f4a9c447de6aa4b0b1b85e5f56de9f729..0d28b8259b9a1e1d736213d884592b7a36aa5d6d 100644 (file)
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -3437,13 +3437,49 @@ static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
        return 0;
 }
 
+/* @depth must not be zero */
+static struct held_lock *find_held_lock(struct task_struct *curr,
+                                       struct lockdep_map *lock,
+                                       unsigned int depth, int *idx)
+{
+       struct held_lock *ret, *hlock, *prev_hlock;
+       int i;
+
+       i = depth - 1;
+       hlock = curr->held_locks + i;
+       ret = hlock;
+       if (match_held_lock(hlock, lock))
+               goto out;
+
+       ret = NULL;
+       for (i--, prev_hlock = hlock--;
+            i >= 0;
+            i--, prev_hlock = hlock--) {
+               /*
+                * We must not cross into another context:
+                */
+               if (prev_hlock->irq_context != hlock->irq_context) {
+                       ret = NULL;
+                       break;
+               }
+               if (match_held_lock(hlock, lock)) {
+                       ret = hlock;
+                       break;
+               }
+       }
+
+out:
+       *idx = i;
+       return ret;
+}
+
 static int
 __lock_set_class(struct lockdep_map *lock, const char *name,
                 struct lock_class_key *key, unsigned int subclass,
                 unsigned long ip)
 {
        struct task_struct *curr = current;
-       struct held_lock *hlock, *prev_hlock;
+       struct held_lock *hlock;
        struct lock_class *class;
        unsigned int depth;
        int i;
@@ -3456,21 +3492,10 @@ __lock_set_class(struct lockdep_map *lock, const char *name,
        if (DEBUG_LOCKS_WARN_ON(!depth))
                return 0;
 
-       prev_hlock = NULL;
-       for (i = depth-1; i >= 0; i--) {
-               hlock = curr->held_locks + i;
-               /*
-                * We must not cross into another context:
-                */
-               if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
-                       break;
-               if (match_held_lock(hlock, lock))
-                       goto found_it;
-               prev_hlock = hlock;
-       }
-       return print_unlock_imbalance_bug(curr, lock, ip);
+       hlock = find_held_lock(curr, lock, depth, &i);
+       if (!hlock)
+               return print_unlock_imbalance_bug(curr, lock, ip);
 
-found_it:
        lockdep_init_map(lock, name, key, 0);
        class = register_lock_class(lock, subclass, 0);
        hlock->class_idx = class - lock_classes + 1;
@@ -3508,7 +3533,7 @@ static int
 __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
 {
        struct task_struct *curr = current;
-       struct held_lock *hlock, *prev_hlock;
+       struct held_lock *hlock;
        unsigned int depth;
        int i;
 
@@ -3527,21 +3552,10 @@ __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
         * Check whether the lock exists in the current stack
         * of held locks:
         */
-       prev_hlock = NULL;
-       for (i = depth-1; i >= 0; i--) {
-               hlock = curr->held_locks + i;
-               /*
-                * We must not cross into another context:
-                */
-               if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
-                       break;
-               if (match_held_lock(hlock, lock))
-                       goto found_it;
-               prev_hlock = hlock;
-       }
-       return print_unlock_imbalance_bug(curr, lock, ip);
+       hlock = find_held_lock(curr, lock, depth, &i);
+       if (!hlock)
+               return print_unlock_imbalance_bug(curr, lock, ip);
 
-found_it:
        if (hlock->instance == lock)
                lock_release_holdtime(hlock);
 
@@ -3903,7 +3917,7 @@ static void
 __lock_contended(struct lockdep_map *lock, unsigned long ip)
 {
        struct task_struct *curr = current;
-       struct held_lock *hlock, *prev_hlock;
+       struct held_lock *hlock;
        struct lock_class_stats *stats;
        unsigned int depth;
        int i, contention_point, contending_point;
@@ -3916,22 +3930,12 @@ __lock_contended(struct lockdep_map *lock, unsigned long ip)
        if (DEBUG_LOCKS_WARN_ON(!depth))
                return;
 
-       prev_hlock = NULL;
-       for (i = depth-1; i >= 0; i--) {
-               hlock = curr->held_locks + i;
-               /*
-                * We must not cross into another context:
-                */
-               if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
-                       break;
-               if (match_held_lock(hlock, lock))
-                       goto found_it;
-               prev_hlock = hlock;
+       hlock = find_held_lock(curr, lock, depth, &i);
+       if (!hlock) {
+               print_lock_contention_bug(curr, lock, ip);
+               return;
        }
-       print_lock_contention_bug(curr, lock, ip);
-       return;
 
-found_it:
        if (hlock->instance != lock)
                return;
 
@@ -3955,7 +3959,7 @@ static void
 __lock_acquired(struct lockdep_map *lock, unsigned long ip)
 {
        struct task_struct *curr = current;
-       struct held_lock *hlock, *prev_hlock;
+       struct held_lock *hlock;
        struct lock_class_stats *stats;
        unsigned int depth;
        u64 now, waittime = 0;
@@ -3969,22 +3973,12 @@ __lock_acquired(struct lockdep_map *lock, unsigned long ip)
        if (DEBUG_LOCKS_WARN_ON(!depth))
                return;
 
-       prev_hlock = NULL;
-       for (i = depth-1; i >= 0; i--) {
-               hlock = curr->held_locks + i;
-               /*
-                * We must not cross into another context:
-                */
-               if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
-                       break;
-               if (match_held_lock(hlock, lock))
-                       goto found_it;
-               prev_hlock = hlock;
+       hlock = find_held_lock(curr, lock, depth, &i);
+       if (!hlock) {
+               print_lock_contention_bug(curr, lock, _RET_IP_);
+               return;
        }
-       print_lock_contention_bug(curr, lock, _RET_IP_);
-       return;
 
-found_it:
        if (hlock->instance != lock)
                return;