[PATCH] rcu_torture_lock deadlock fix

rcu_torture_lock is used in a softirq-unsafe manner, but it is also
taken by rcu_torture_cb(), which may execute in softirq-context,
resulting in potential deadlocks.

The fix is to acquire rcu_torture_lock in a softirq-safe manner.  With
this fix applied, the rcu-torture code passes validation.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Paul E. McKenney <paulmck@us.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 5 insertions, 5 deletions

diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c
index 773219907dd8..7712912dbc84 100644
--- a/kernel/rcutorture.c
+++ b/kernel/rcutorture.c
@@ -114,16 +114,16 @@ rcu_torture_alloc(void)
 {
         struct list_head *p;
 
-        spin_lock(&rcu_torture_lock);
+        spin_lock_bh(&rcu_torture_lock);
         if (list_empty(&rcu_torture_freelist)) {
                 atomic_inc(&n_rcu_torture_alloc_fail);
-                spin_unlock(&rcu_torture_lock);
+                spin_unlock_bh(&rcu_torture_lock);
                 return NULL;
         }
         atomic_inc(&n_rcu_torture_alloc);
         p = rcu_torture_freelist.next;
         list_del_init(p);
-        spin_unlock(&rcu_torture_lock);
+        spin_unlock_bh(&rcu_torture_lock);
         return container_of(p, struct rcu_torture, rtort_free);
 }
 
@@ -134,9 +134,9 @@ static void
 rcu_torture_free(struct rcu_torture *p)
 {
         atomic_inc(&n_rcu_torture_free);
-        spin_lock(&rcu_torture_lock);
+        spin_lock_bh(&rcu_torture_lock);
         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
-        spin_unlock(&rcu_torture_lock);
+        spin_unlock_bh(&rcu_torture_lock);
 }
 
 static void