lockdep: Simplify lock_release()

lock_release() takes this nested argument that's mostly pointless
these days, remove the implementation but leave the argument a
rudiment for now.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: ktkhai@parallels.com
Cc: rostedt@goodmis.org
Cc: juri.lelli@gmail.com
Cc: pang.xunlei@linaro.org
Cc: oleg@redhat.com
Cc: wanpeng.li@linux.intel.com
Cc: umgwanakikbuti@gmail.com
Link: http://lkml.kernel.org/r/20150611124743.840411606@infradead.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 18 insertions, 101 deletions

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index a0831e1b99f4..a266d5165b63 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -3260,26 +3260,6 @@ print_unlock_imbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
         return 0;
 }
 
-/*
- * Common debugging checks for both nested and non-nested unlock:
- */
-static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
-                        unsigned long ip)
-{
-        if (unlikely(!debug_locks))
-                return 0;
-        /*
-         * Lockdep should run with IRQs disabled, recursion, head-ache, etc..
-         */
-        if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
-                return 0;
-
-        if (curr->lockdep_depth <= 0)
-                return print_unlock_imbalance_bug(curr, lock, ip);
-
-        return 1;
-}
-
 static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
 {
         if (hlock->instance == lock)
@@ -3376,31 +3356,35 @@ found_it:
 }
 
 /*
- * Remove the lock to the list of currently held locks in a
- * potentially non-nested (out of order) manner. This is a
- * relatively rare operation, as all the unlock APIs default
- * to nested mode (which uses lock_release()):
+ * Remove the lock to the list of currently held locks - this gets
+ * called on mutex_unlock()/spin_unlock*() (or on a failed
+ * mutex_lock_interruptible()).
+ *
+ * @nested is an hysterical artifact, needs a tree wide cleanup.
  */
 static int
-lock_release_non_nested(struct task_struct *curr,
-                        struct lockdep_map *lock, unsigned long ip)
+__lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
 {
+        struct task_struct *curr = current;
         struct held_lock *hlock, *prev_hlock;
         unsigned int depth;
         int i;
 
-        /*
-         * Check whether the lock exists in the current stack
-         * of held locks:
-         */
+        if (unlikely(!debug_locks))
+                return 0;
+
         depth = curr->lockdep_depth;
         /*
          * So we're all set to release this lock.. wait what lock? We don't
          * own any locks, you've been drinking again?
          */
-        if (DEBUG_LOCKS_WARN_ON(!depth))
-                return 0;
+        if (DEBUG_LOCKS_WARN_ON(depth <= 0))
+                 return print_unlock_imbalance_bug(curr, lock, 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;
@@ -3456,78 +3440,10 @@ found_it:
          */
         if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
                 return 0;
-        return 1;
-}
-
-/*
- * Remove the lock to the list of currently held locks - this gets
- * called on mutex_unlock()/spin_unlock*() (or on a failed
- * mutex_lock_interruptible()). This is done for unlocks that nest
- * perfectly. (i.e. the current top of the lock-stack is unlocked)
- */
-static int lock_release_nested(struct task_struct *curr,
-                               struct lockdep_map *lock, unsigned long ip)
-{
-        struct held_lock *hlock;
-        unsigned int depth;
-
-        /*
-         * Pop off the top of the lock stack:
-         */
-        depth = curr->lockdep_depth - 1;
-        hlock = curr->held_locks + depth;
-
-        /*
-         * Is the unlock non-nested:
-         */
-        if (hlock->instance != lock || hlock->references)
-                return lock_release_non_nested(curr, lock, ip);
-        curr->lockdep_depth--;
-
-        /*
-         * No more locks, but somehow we've got hash left over, who left it?
-         */
-        if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
-                return 0;
-
-        curr->curr_chain_key = hlock->prev_chain_key;
-
-        lock_release_holdtime(hlock);
 
-#ifdef CONFIG_DEBUG_LOCKDEP
-        hlock->prev_chain_key = 0;
-        hlock->class_idx = 0;
-        hlock->acquire_ip = 0;
-        hlock->irq_context = 0;
-#endif
         return 1;
 }
 
-/*
- * Remove the lock to the list of currently held locks - this gets
- * called on mutex_unlock()/spin_unlock*() (or on a failed
- * mutex_lock_interruptible()). This is done for unlocks that nest
- * perfectly. (i.e. the current top of the lock-stack is unlocked)
- */
-static void
-__lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
-{
-        struct task_struct *curr = current;
-
-        if (!check_unlock(curr, lock, ip))
-                return;
-
-        if (nested) {
-                if (!lock_release_nested(curr, lock, ip))
-                        return;
-        } else {
-                if (!lock_release_non_nested(curr, lock, ip))
-                        return;
-        }
-
-        check_chain_key(curr);
-}
-
 static int __lock_is_held(struct lockdep_map *lock)
 {
         struct task_struct *curr = current;
@@ -3639,7 +3555,8 @@ void lock_release(struct lockdep_map *lock, int nested,
         check_flags(flags);
         current->lockdep_recursion = 1;
         trace_lock_release(lock, ip);
-        __lock_release(lock, nested, ip);
+        if (__lock_release(lock, nested, ip))
+                check_chain_key(current);
         current->lockdep_recursion = 0;
         raw_local_irq_restore(flags);
 }