[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>

diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index e33f620..f76a24f 100644 (file)
--- 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