rcu: Fix hlist_bl_set_first_rcu() annotation

Abhi noticed that we were getting a complaint from the RCU subsystem
about access of an RCU protected list under the write side bit lock.
This commit adds additional annotation to check both the RCU read
lock and the write side bit lock before printing a message.

Reported by: Abhijith Das <adas@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Tested-by: Abhijith Das <adas@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

diff --git a/include/linux/list_bl.h b/include/linux/list_bl.h
index 31f9d75adc5bfaf4489d94473500cc01f74b2973..2eb88556c5c5b0ee0cb0fc664e9d13dc852fea6e 100644 (file)
--- a/include/linux/list_bl.h
+++ b/include/linux/list_bl.h
@@ -125,6 +125,11 @@ static inline void hlist_bl_unlock(struct hlist_bl_head *b)
        __bit_spin_unlock(0, (unsigned long *)b);
 }
 
+static inline bool hlist_bl_is_locked(struct hlist_bl_head *b)
+{
+       return bit_spin_is_locked(0, (unsigned long *)b);
+}
+
 /**
  * hlist_bl_for_each_entry     - iterate over list of given type
  * @tpos:      the type * to use as a loop cursor.

diff --git a/include/linux/rculist_bl.h b/include/linux/rculist_bl.h
index cf1244fbf3b66cc444ad80854d7e0126d45cfb09..4f216c59e7dbf83eec7b0c14538c22997409ea4d 100644 (file)
--- a/include/linux/rculist_bl.h
+++ b/include/linux/rculist_bl.h
@@ -20,7 +20,7 @@ static inline void hlist_bl_set_first_rcu(struct hlist_bl_head *h,
 static inline struct hlist_bl_node *hlist_bl_first_rcu(struct hlist_bl_head *h)
 {
        return (struct hlist_bl_node *)
-               ((unsigned long)rcu_dereference(h->first) & ~LIST_BL_LOCKMASK);
+               ((unsigned long)rcu_dereference_check(h->first, hlist_bl_is_locked(h)) & ~LIST_BL_LOCKMASK);
 }
 
 /**