[GIT PULL] locking fix

[Ingo Molnar]

Linus,

Please pull the latest locking-urgent-for-linus git tree from:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git 
locking-urgent-for-linus

   # HEAD: 90c1cba2b3b3851c151229f61801919b2904d437 locking/lockdep: Zap lock 
classes even with lock debugging disabled

Fixes a crash when accessing /proc/lockdep.

 Thanks,

        Ingo

------------------>
Bart Van Assche (1):
      locking/lockdep: Zap lock classes even with lock debugging disabled


 kernel/locking/lockdep.c | 29 ++++++++++++-----------------
 1 file changed, 12 insertions(+), 17 deletions(-)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 34cdcbedda49..e16766ff184b 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -4689,8 +4689,8 @@ static void free_zapped_rcu(struct rcu_head *ch)
                return;
 
        raw_local_irq_save(flags);
-       if (!graph_lock())
-               goto out_irq;
+       arch_spin_lock(&lockdep_lock);
+       current->lockdep_recursion = 1;
 
        /* closed head */
        pf = delayed_free.pf + (delayed_free.index ^ 1);
@@ -4702,8 +4702,8 @@ static void free_zapped_rcu(struct rcu_head *ch)
         */
        call_rcu_zapped(delayed_free.pf + delayed_free.index);
 
-       graph_unlock();
-out_irq:
+       current->lockdep_recursion = 0;
+       arch_spin_unlock(&lockdep_lock);
        raw_local_irq_restore(flags);
 }
 
@@ -4744,21 +4744,17 @@ static void lockdep_free_key_range_reg(void *start, 
unsigned long size)
 {
        struct pending_free *pf;
        unsigned long flags;
-       int locked;
 
        init_data_structures_once();
 
        raw_local_irq_save(flags);
-       locked = graph_lock();
-       if (!locked)
-               goto out_irq;
-
+       arch_spin_lock(&lockdep_lock);
+       current->lockdep_recursion = 1;
        pf = get_pending_free();
        __lockdep_free_key_range(pf, start, size);
        call_rcu_zapped(pf);
-
-       graph_unlock();
-out_irq:
+       current->lockdep_recursion = 0;
+       arch_spin_unlock(&lockdep_lock);
        raw_local_irq_restore(flags);
 
        /*
@@ -4911,9 +4907,8 @@ void lockdep_unregister_key(struct lock_class_key *key)
                return;
 
        raw_local_irq_save(flags);
-       if (!graph_lock())
-               goto out_irq;
-
+       arch_spin_lock(&lockdep_lock);
+       current->lockdep_recursion = 1;
        pf = get_pending_free();
        hlist_for_each_entry_rcu(k, hash_head, hash_entry) {
                if (k == key) {
@@ -4925,8 +4920,8 @@ void lockdep_unregister_key(struct lock_class_key *key)
        WARN_ON_ONCE(!found);
        __lockdep_free_key_range(pf, key, 1);
        call_rcu_zapped(pf);
-       graph_unlock();
-out_irq:
+       current->lockdep_recursion = 0;
+       arch_spin_unlock(&lockdep_lock);
        raw_local_irq_restore(flags);
 
        /* Wait until is_dynamic_key() has finished accessing k->hash_entry. */