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>

1 files changed, 54 insertions, 60 deletions

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index a95e5d1f4a9c..0d28b8259b9a 100644
--- 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;