* @inends: input side of the edge
*
* Function call moves output side of the edge from idle onto active edges
- * list.
+ * list. This function has to be called with edge reference count held.
+ * that is same as for most of other edge functions.
*/
static inline
void canque_activate_edge(struct canque_ends_t *inends, struct canque_edge_t *qedge)
struct canque_ends_t *outends;
if(qedge->edge_prio>=CANQUEUE_PRIO_NR)
qedge->edge_prio=CANQUEUE_PRIO_NR-1;
- can_spin_lock_irqsave(&inends->ends_lock, flags);
if((outends=qedge->outends)){
- can_spin_lock(&outends->ends_lock);
+ can_spin_lock_irqsave(&outends->ends_lock, flags);
can_spin_lock(&qedge->fifo.fifo_lock);
if(!canque_fifo_test_fl(&qedge->fifo,EMPTY)){
list_del(&qedge->activepeers);
list_add_tail(&qedge->activepeers,&outends->active[qedge->edge_prio]);
}
can_spin_unlock(&qedge->fifo.fifo_lock);
- can_spin_unlock(&outends->ends_lock);
-
+ can_spin_unlock_irqrestore(&outends->ends_lock, flags);
}
- can_spin_unlock_irqrestore(&inends->ends_lock, flags);
}
/**
/* edge reference and traversal functions */
-void canque_edge_do_dead(struct canque_edge_t *edge, int dead_fl);
+void canque_edge_do_dead(struct canque_edge_t *edge);
+/**
+ * canque_edge_incref - increments edge reference count
+ * @qedg: pointer to the edge structure
+ */
static inline
void canque_edge_incref(struct canque_edge_t *edge)
{
}
static inline
-void canque_edge_decref(struct canque_edge_t *edge)
+can_spin_irqflags_t canque_edge_lock_both_ends(struct canque_edge_t *edge)
+{
+ can_spin_irqflags_t flags;
+ if(edge->inends<edge->outends) {
+ can_spin_lock_irqsave(&edge->inends->ends_lock, flags);
+ can_spin_lock(&edge->outends->ends_lock);
+ }else{
+ can_spin_lock_irqsave(&edge->outends->ends_lock, flags);
+ if(edge->outends!=edge->inends) can_spin_lock(&edge->inends->ends_lock);
+ }
+ return flags;
+}
+
+static inline
+void canque_edge_unlock_both_ends(struct canque_edge_t *edge, can_spin_irqflags_t flags)
+{
+ if(edge->outends!=edge->inends) can_spin_unlock(&edge->outends->ends_lock);
+ can_spin_unlock_irqrestore(&edge->inends->ends_lock, flags);
+}
+
+/* Non-inlined version of edge reference decrement */
+void __canque_edge_decref(struct canque_edge_t *edge);
+
+static inline
+void __canque_edge_decref_body(struct canque_edge_t *edge)
{
can_spin_irqflags_t flags;
- struct canque_ends_t *inends=edge->inends;
- struct canque_ends_t *outends=edge->outends;
- int dead_fl;
+ int dead_fl=0;
- can_spin_lock_irqsave(&inends->ends_lock, flags);
- can_spin_lock(&outends->ends_lock);
+ flags=canque_edge_lock_both_ends(edge);
if(atomic_dec_and_test(&edge->edge_used)) {
- dead_fl=canque_fifo_test_and_set_fl(&edge->fifo,DEAD);
+ dead_fl=!canque_fifo_test_and_set_fl(&edge->fifo,DEAD);
/* Because of former evolution of edge references
management notify of CANQUEUE_NOTIFY_NOUSR could
be moved to canque_edge_do_dead :-) */
- can_spin_unlock(&outends->ends_lock);
- can_spin_unlock_irqrestore(&inends->ends_lock, flags);
- canque_edge_do_dead(edge, dead_fl);
- } else {
- can_spin_unlock(&outends->ends_lock);
- can_spin_unlock_irqrestore(&inends->ends_lock, flags);
}
+ canque_edge_unlock_both_ends(edge, flags);
+ if(dead_fl) canque_edge_do_dead(edge);
+}
+
+#ifndef CAN_HAVE_ARCH_CMPXCHG
+/**
+ * canque_edge_decref - decrements edge reference count
+ * @qedg: pointer to the edge structure
+ *
+ * This function has to be called without lock held for both ends of edge.
+ * If reference count drops to 0, function canque_edge_do_dead()
+ * is called.
+ */
+static inline
+void canque_edge_decref(struct canque_edge_t *edge)
+{
+ __canque_edge_decref_body(edge);
+}
+#else
+static inline
+void canque_edge_decref(struct canque_edge_t *edge)
+{
+ int x, y;
+
+ x = atomic_read(&edge->edge_used);
+ do{
+ if(x<=1)
+ return __canque_edge_decref(edge);
+ y=x;
+ /* This code strongly depends on the definition of atomic_t !!!! */
+ /* x=cmpxchg(&edge->edge_used, x, x-1); */
+ /* Next alternative could be more portable */
+ x=__cmpxchg(&edge->edge_used, x, x-1, sizeof(atomic_t));
+ /* If even this does not help, comment out CAN_HAVE_ARCH_CMPXCHG in can_sysdep.h */
+ } while(x!=y);
}
+#endif
static inline
struct canque_edge_t *canque_first_inedge(struct canque_ends_t *qends)
list_entry(ptr, type, member)
*/
+void __canque_edge_decref(struct canque_edge_t *edge)
+{
+ __canque_edge_decref_body(edge);
+}
+
/**
* canque_get_inslot - finds one outgoing edge and allocates slot from it
* @qends: ends structure belonging to calling communication object
if(qedge == NULL) return -1;
DEBUGQUE("canqueue_connect_edge %d\n",qedge->edge_num);
canque_edge_incref(qedge);
- can_spin_lock_irqsave(&inends->ends_lock, flags);
- can_spin_lock(&outends->ends_lock);
+ flags=canque_edge_lock_both_ends(qedge);
can_spin_lock(&qedge->fifo.fifo_lock);
qedge->inends=inends;
list_add(&qedge->inpeers,&inends->inlist);
list_add(&qedge->outpeers,&outends->outlist);
list_add(&qedge->activepeers,&outends->idle);
can_spin_unlock(&qedge->fifo.fifo_lock);
- can_spin_unlock(&outends->ends_lock);
- can_spin_unlock_irqrestore(&inends->ends_lock, flags);
+ canque_edge_unlock_both_ends(qedge, flags);
canque_notify_bothends(qedge, CANQUEUE_NOTIFY_ATTACH);
if(canque_fifo_test_and_set_fl(&qedge->fifo, READY))
struct canque_ends_t *inends, *outends;
inends=qedge->inends;
- if(inends) can_spin_lock_irqsave(&inends->ends_lock,flags);
outends=qedge->outends;
- if(outends) can_spin_lock(&outends->ends_lock);
+
+ if(inends && outends) {
+ flags=canque_edge_lock_both_ends(qedge);
+ } else {
+ DEBUGQUE("canqueue_disconnect_edge called with not fully connected edge");
+ if(inends) can_spin_lock_irqsave(&inends->ends_lock,flags);
+ if(outends) can_spin_lock(&outends->ends_lock);
+ flags=0;
+ }
+
can_spin_lock(&qedge->fifo.fifo_lock);
if(atomic_read(&qedge->edge_used)==0) {
if(qedge->outends){
ret=1;
} else ret=-1;
can_spin_unlock(&qedge->fifo.fifo_lock);
- if(outends) can_spin_unlock(&outends->ends_lock);
- if(inends) can_spin_unlock_irqrestore(&inends->ends_lock,flags);
+
+ if(inends && outends) {
+ canque_edge_unlock_both_ends(qedge, flags);
+ } else {
+ if(outends) can_spin_unlock(&outends->ends_lock);
+ if(inends) can_spin_unlock_irqrestore(&inends->ends_lock,flags);
+ }
+
DEBUGQUE("canqueue_disconnect_edge %d returned %d\n",qedge->edge_num,ret);
return ret;
}