[RFC PATCH 12/21] list: Poison ->next pointer for non-RCU deletion of 'hlist_nulls_node'

[Will Deacon]

hlist_nulls_del() is used for non-RCU deletion of an 'hlist_nulls_node'
and so we can safely poison the ->next pointer without having to worry
about concurrent readers, just like we do for other non-RCU list
deletion primitives

Cc: Paul E. McKenney <paulmck@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Signed-off-by: Will Deacon <will@xxxxxxxxxx>
---
 include/linux/list_nulls.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/linux/list_nulls.h b/include/linux/list_nulls.h
index fd154ceb5b0d..48f33ae16381 100644
--- a/include/linux/list_nulls.h
+++ b/include/linux/list_nulls.h
@@ -99,6 +99,7 @@ static inline void __hlist_nulls_del(struct hlist_nulls_node *n)
 static inline void hlist_nulls_del(struct hlist_nulls_node *n)
 {
 	__hlist_nulls_del(n);
+	n->next = LIST_POISON1;
 	n->pprev = LIST_POISON2;
 }
 
-- 
2.20.1