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>

diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 723bd9f9255687f7820b0e151ae23a3d5ca81e7b..4335f12a27c6367e8e264a1128050ea3df6e8415 100644 (file)
--- 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);