[PATCH] lockdep: internal locking fixes

Here are mainly some lockdep returns with 0 with unlocking fixes.

Signed-off-by: Jarek Poplawski <jarkao2@o2.pl>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 15 insertions, 10 deletions

diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index e33f6207f5b3..f76a24f2ac20 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -237,8 +237,10 @@ e	   locks. */
         trace->max_entries = trace->nr_entries;
 
         nr_stack_trace_entries += trace->nr_entries;
-        if (DEBUG_LOCKS_WARN_ON(nr_stack_trace_entries > MAX_STACK_TRACE_ENTRIES))
+        if (DEBUG_LOCKS_WARN_ON(nr_stack_trace_entries > MAX_STACK_TRACE_ENTRIES)) {
+                __raw_spin_unlock(&hash_lock);
                 return 0;
+        }
 
         if (nr_stack_trace_entries == MAX_STACK_TRACE_ENTRIES) {
                 __raw_spin_unlock(&hash_lock);
@@ -474,7 +476,8 @@ static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
                 return 0;
 
         entry->class = this;
-        save_trace(&entry->trace);
+        if (!save_trace(&entry->trace))
+                return 0;
 
         /*
          * Since we never remove from the dependency list, the list can
@@ -562,8 +565,12 @@ static noinline int print_circular_bug_tail(void)
         if (debug_locks_silent)
                 return 0;
 
+        /* hash_lock unlocked by the header */
+        __raw_spin_lock(&hash_lock);
         this.class = check_source->class;
-        save_trace(&this.trace);
+        if (!save_trace(&this.trace))
+                return 0;
+        __raw_spin_unlock(&hash_lock);
         print_circular_bug_entry(&this, 0);
 
         printk("\nother info that might help us debug this:\n\n");
@@ -966,14 +973,11 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev,
                                &prev->class->locks_after, next->acquire_ip);
         if (!ret)
                 return 0;
-        /*
-         * Return value of 2 signals 'dependency already added',
-         * in that case we dont have to add the backlink either.
-         */
-        if (ret == 2)
-                return 2;
+
         ret = add_lock_to_list(next->class, prev->class,
                                &next->class->locks_before, next->acquire_ip);
+        if (!ret)
+                return 0;
 
         /*
          * Debugging printouts:
@@ -1025,7 +1029,8 @@ check_prevs_add(struct task_struct *curr, struct held_lock *next)
                  * added:
                  */
                 if (hlock->read != 2) {
-                        check_prev_add(curr, hlock, next);
+                        if (!check_prev_add(curr, hlock, next))
+                                return 0;
                         /*
                          * Stop after the first non-trylock entry,
                          * as non-trylock entries have added their