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>

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index a0831e1b99f4aabd6c80ea68cedb6350a7a9affc..a266d5165b6355d643fc73e31f54bb323a1c7aed 100644 (file)
--- 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);
 }