lockdep: fix internal double unlock during self-test

Lockdep, during self-test (when it was simulating double unlocks) was
sometimes unconditionally unlocking a spinlock when it had not been
locked. This won't work for ticket locks.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>

1 files changed, 8 insertions, 4 deletions

diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 723bd9f92556..4335f12a27c6 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -2943,9 +2943,10 @@ void lockdep_free_key_range(void *start, unsigned long size)
         struct list_head *head;
         unsigned long flags;
         int i;
+        int locked;
 
         raw_local_irq_save(flags);
-        graph_lock();
+        locked = graph_lock();
 
         /*
          * Unhash all classes that were created by this module:
@@ -2959,7 +2960,8 @@ void lockdep_free_key_range(void *start, unsigned long size)
                                 zap_class(class);
         }
 
-        graph_unlock();
+        if (locked)
+                graph_unlock();
         raw_local_irq_restore(flags);
 }
 
@@ -2969,6 +2971,7 @@ void lockdep_reset_lock(struct lockdep_map *lock)
         struct list_head *head;
         unsigned long flags;
         int i, j;
+        int locked;
 
         raw_local_irq_save(flags);
 
@@ -2987,7 +2990,7 @@ void lockdep_reset_lock(struct lockdep_map *lock)
          * Debug check: in the end all mapped classes should
          * be gone.
          */
-        graph_lock();
+        locked = graph_lock();
         for (i = 0; i < CLASSHASH_SIZE; i++) {
                 head = classhash_table + i;
                 if (list_empty(head))
@@ -3000,7 +3003,8 @@ void lockdep_reset_lock(struct lockdep_map *lock)
                         }
                 }
         }
-        graph_unlock();
+        if (locked)
+                graph_unlock();
 
 out_restore:
         raw_local_irq_restore(flags);