From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Fri, 21 Jun 2013 21:29:42 +0000 (-0400)
Subject: rcuhlist: make pointer stores atomic
X-Git-Tag: v0.8.0~37
X-Git-Url: https://git.lttng.org/?p=urcu.git;a=commitdiff_plain;h=90bdf188e835cadbc12d5fa7e4523056ecd97cf4

rcuhlist: make pointer stores atomic

Use rcu_assign_pointer() to store into head->next in
cds_hlist_add_head_rcu(). This includes the write barrier needed before
publishing the new node.

Use CMM_STORE_SHARED() to store into elem->prev->next in
cds_hlist_del_rcu().

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/urcu/rcuhlist.h b/urcu/rcuhlist.h
index 36da15b..6d88692 100644
--- a/urcu/rcuhlist.h
+++ b/urcu/rcuhlist.h
@@ -36,10 +36,9 @@ void cds_hlist_add_head_rcu(struct cds_hlist_node *newp,
 {
 	newp->next = head->next;
 	newp->prev = (struct cds_hlist_node *)head;
-	cmm_smp_wmb();
 	if (head->next)
 		head->next->prev = newp;
-	head->next = newp;
+	rcu_assign_pointer(head->next, newp);
 }
 
 /* Remove element from list. */
@@ -48,7 +47,7 @@ void cds_hlist_del_rcu(struct cds_hlist_node *elem)
 {
 	if (elem->next)
 		elem->next->prev = elem->prev;
-	elem->prev->next = elem->next;
+	CMM_STORE_SHARED(elem->prev->next, elem->next);
 }
 
 /*