Implement waitqueue and workqueue APIs

[userspace-rcu.git] / urcu / static / wfcqueue.h

diff --git a/urcu/static/wfcqueue.h b/urcu/static/wfcqueue.h
index 48b2625dd3a4d0b28450dac4d7d0f7df921028c7..b2ad7ab6957699d36ca3100737b8086683b4165b 100644 (file)
--- a/urcu/static/wfcqueue.h
+++ b/urcu/static/wfcqueue.h
@@ -367,7 +367,8 @@ static inline struct cds_wfcq_node *
 ___cds_wfcq_dequeue_with_state(cds_wfcq_head_ptr_t u_head,
                struct cds_wfcq_tail *tail,
                int *state,
-               int blocking)
+               int blocking,
+               int safe)
 {
        struct __cds_wfcq_head *head = u_head._h;
        struct cds_wfcq_node *node, *next;
@@ -385,6 +386,8 @@ ___cds_wfcq_dequeue_with_state(cds_wfcq_head_ptr_t u_head,
        }
 
        if ((next = CMM_LOAD_SHARED(node->next)) == NULL) {
+               struct cds_wfcq_node *ret_node;
+
                /*
                 * @node is probably the only node in the queue.
                 * Try to move the tail to &q->head.
@@ -400,7 +403,15 @@ ___cds_wfcq_dequeue_with_state(cds_wfcq_head_ptr_t u_head,
                 * content.
                 */
                _cds_wfcq_node_init(&head->node);
-               if (uatomic_cmpxchg(&tail->p, node, &head->node) == node) {
+               if (safe) {
+                       ret_node = uatomic_cmpxchg(&tail->p, node,
+                                       &head->node);
+               } else {
+                       ret_node = tail->p;
+                       if (ret_node == node)
+                               tail->p = &head->node;
+               }
+               if (ret_node == node) {
                        if (state)
                                *state |= CDS_WFCQ_STATE_LAST;
                        return node;
@@ -440,7 +451,7 @@ static inline struct cds_wfcq_node *
 ___cds_wfcq_dequeue_with_state_blocking(cds_wfcq_head_ptr_t head,
                struct cds_wfcq_tail *tail, int *state)
 {
-       return ___cds_wfcq_dequeue_with_state(head, tail, state, 1);
+       return ___cds_wfcq_dequeue_with_state(head, tail, state, 1, 1);
 }
 
 /*
@@ -466,7 +477,7 @@ static inline struct cds_wfcq_node *
 ___cds_wfcq_dequeue_with_state_nonblocking(cds_wfcq_head_ptr_t head,
                struct cds_wfcq_tail *tail, int *state)
 {
-       return ___cds_wfcq_dequeue_with_state(head, tail, state, 0);
+       return ___cds_wfcq_dequeue_with_state(head, tail, state, 0, 1);
 }
 
 /*