Re: [PATCH v2] rcu: fix a race in hlist_nulls_for_each_entry_rcumacro

From: Roman Gushchin
Date: Wed May 29 2013 - 05:18:10 EST


On 29.05.2013 04:34, Eric Dumazet wrote:
On Tue, 2013-05-28 at 13:10 +0400, Roman Gushchin wrote:
On 28.05.2013 04:12, Eric Dumazet wrote:

Adding a barrier() is probably what we want.

I agree, inserting barrier() is also a correct and working fix.

Yeah, but I can not find a clean way to put it inside the "for (;;)"

diff --git a/include/linux/rculist_nulls.h b/include/linux/rculist_nulls.h
index 2ae1371..74d5065 100644
--- a/include/linux/rculist_nulls.h
+++ b/include/linux/rculist_nulls.h
@@ -107,7 +107,7 @@ 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_raw(hlist_nulls_first_rcu(head)); \
+ for (({barrier();}), pos = rcu_dereference_raw(hlist_nulls_first_rcu(head)); \
(!is_a_nulls(pos)) && \
({ tpos = hlist_nulls_entry(pos, typeof(*tpos), member); 1; }); \
pos = rcu_dereference_raw(hlist_nulls_next_rcu(pos)))



--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/