rcu: Disable lockdep checking in RCU list-traversal primitives
Paul E. McKenney [Tue, 23 Feb 2010 01:04:48 +0000 (17:04 -0800)]
The theory is that use of bare rcu_dereference() is more prone
to error than use of the RCU list-traversal primitives.
Therefore, disable lockdep RCU read-side critical-section
checking in these primitives for the time being.  Once all of
the rcu_dereference() uses have been dealt with, it may be time
to re-enable lockdep checking for the RCU list-traversal
primitives.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <1266887105-1528-4-git-send-email-paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

include/linux/rculist.h
include/linux/rculist_nulls.h

index 1bf0f70..779d707 100644 (file)
@@ -208,7 +208,7 @@ static inline void list_splice_init_rcu(struct list_head *list,
  * primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock().
  */
 #define list_entry_rcu(ptr, type, member) \
-       container_of(rcu_dereference(ptr), type, member)
+       container_of(rcu_dereference_raw(ptr), type, member)
 
 /**
  * list_first_entry_rcu - get the first element from a list
@@ -225,9 +225,9 @@ static inline void list_splice_init_rcu(struct list_head *list,
        list_entry_rcu((ptr)->next, type, member)
 
 #define __list_for_each_rcu(pos, head) \
-       for (pos = rcu_dereference((head)->next); \
+       for (pos = rcu_dereference_raw((head)->next); \
                pos != (head); \
-               pos = rcu_dereference(pos->next))
+               pos = rcu_dereference_raw(pos->next))
 
 /**
  * list_for_each_entry_rcu     -       iterate over rcu list of given type
@@ -257,9 +257,9 @@ static inline void list_splice_init_rcu(struct list_head *list,
  * as long as the traversal is guarded by rcu_read_lock().
  */
 #define list_for_each_continue_rcu(pos, head) \
-       for ((pos) = rcu_dereference((pos)->next); \
+       for ((pos) = rcu_dereference_raw((pos)->next); \
                prefetch((pos)->next), (pos) != (head); \
-               (pos) = rcu_dereference((pos)->next))
+               (pos) = rcu_dereference_raw((pos)->next))
 
 /**
  * list_for_each_entry_continue_rcu - continue iteration over list of given type
@@ -418,10 +418,10 @@ static inline void hlist_add_after_rcu(struct hlist_node *prev,
  * as long as the traversal is guarded by rcu_read_lock().
  */
 #define hlist_for_each_entry_rcu(tpos, pos, head, member)               \
-       for (pos = rcu_dereference((head)->first);                       \
+       for (pos = rcu_dereference_raw((head)->first);                   \
                pos && ({ prefetch(pos->next); 1; }) &&                  \
                ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1; }); \
-               pos = rcu_dereference(pos->next))
+               pos = rcu_dereference_raw(pos->next))
 
 #endif /* __KERNEL__ */
 #endif
index 589a409..b70ffe5 100644 (file)
@@ -101,10 +101,10 @@ static inline void hlist_nulls_add_head_rcu(struct hlist_nulls_node *n,
  *
  */
 #define hlist_nulls_for_each_entry_rcu(tpos, pos, head, member) \
-       for (pos = rcu_dereference((head)->first);                       \
+       for (pos = rcu_dereference_raw((head)->first);                   \
                (!is_a_nulls(pos)) &&                   \
                ({ tpos = hlist_nulls_entry(pos, typeof(*tpos), member); 1; }); \
-               pos = rcu_dereference(pos->next))
+               pos = rcu_dereference_raw(pos->next))
 
 #endif
 #endif