+/**
+ * @internal Dequeue several objects from a ring (multi-consumers safe). When
+ * the request objects are more than the available objects, only dequeue the
+ * actual number of objects
+ *
+ * This function uses a "compare and set" instruction to move the
+ * consumer index atomically.
+ *
+ * @param r
+ * A pointer to the ring structure.
+ * @param obj_table
+ * A pointer to a table of void * pointers (objects) that will be filled.
+ * @param n
+ * The number of objects to dequeue from the ring to the obj_table.
+ * @param behavior
+ * RTE_RING_QUEUE_FIXED: Dequeue a fixed number of items from a ring
+ * RTE_RING_QUEUE_VARIABLE: Dequeue as many items a possible from ring
+ * @return
+ * Depend on the behavior value
+ * if behavior = RTE_RING_QUEUE_FIXED
+ * - 0: Success; objects dequeued.
+ * - -ENOENT: Not enough entries in the ring to dequeue; no object is
+ * dequeued.
+ * if behavior = RTE_RING_QUEUE_VARIABLE
+ * - n: Actual number of objects dequeued.
+ */
+
+static inline int __attribute__((always_inline))
+__rte_ring_mc_do_dequeue(struct rte_ring *r, void **obj_table,
+ unsigned n, enum rte_ring_queue_behavior behavior)
+{
+ uint32_t cons_head, prod_tail;
+ uint32_t cons_next, entries;
+ const unsigned max = n;
+ int success;
+ unsigned i, rep = 0;
+ uint32_t mask = r->prod.mask;
+
+ /* move cons.head atomically */
+ do {
+ /* Restore n as it may change every loop */
+ n = max;
+
+ cons_head = r->cons.head;
+ prod_tail = r->prod.tail;
+ /* The subtraction is done between two unsigned 32bits value
+ * (the result is always modulo 32 bits even if we have
+ * cons_head > prod_tail). So 'entries' is always between 0
+ * and size(ring)-1. */
+ entries = (prod_tail - cons_head);
+
+ /* Set the actual entries for dequeue */
+ if (n > entries) {
+ if (behavior == RTE_RING_QUEUE_FIXED) {
+ __RING_STAT_ADD(r, deq_fail, n);
+ return -ENOENT;
+ }
+ else {
+ if (unlikely(entries == 0)){
+ __RING_STAT_ADD(r, deq_fail, n);
+ return 0;
+ }
+
+ n = entries;
+ }
+ }
+
+ cons_next = cons_head + n;
+ success = rte_atomic32_cmpset(&r->cons.head, cons_head,
+ cons_next);
+ } while (unlikely(success == 0));
+
+ /* copy in table */
+ DEQUEUE_PTRS();
+ rte_compiler_barrier();
+
+ /*
+ * If there are other dequeues in progress that preceded us,
+ * we need to wait for them to complete
+ */
+ while (unlikely(r->cons.tail != cons_head)) {
+ rte_pause();
+
+ /* Set RTE_RING_PAUSE_REP_COUNT to avoid spin too long waiting
+ * for other thread finish. It gives pre-empted thread a chance
+ * to proceed and finish with ring dequeue operation. */
+ if (RTE_RING_PAUSE_REP_COUNT &&
+ ++rep == RTE_RING_PAUSE_REP_COUNT) {
+ rep = 0;
+ sched_yield();
+ }
+ }
+ __RING_STAT_ADD(r, deq_success, n);
+ r->cons.tail = cons_next;
+
+ return behavior == RTE_RING_QUEUE_FIXED ? 0 : n;
+}
+
+/**
+ * @internal Dequeue several objects from a ring (NOT multi-consumers safe).
+ * When the request objects are more than the available objects, only dequeue
+ * the actual number of objects
+ *
+ * @param r
+ * A pointer to the ring structure.
+ * @param obj_table
+ * A pointer to a table of void * pointers (objects) that will be filled.
+ * @param n
+ * The number of objects to dequeue from the ring to the obj_table.
+ * @param behavior
+ * RTE_RING_QUEUE_FIXED: Dequeue a fixed number of items from a ring
+ * RTE_RING_QUEUE_VARIABLE: Dequeue as many items a possible from ring
+ * @return
+ * Depend on the behavior value
+ * if behavior = RTE_RING_QUEUE_FIXED
+ * - 0: Success; objects dequeued.
+ * - -ENOENT: Not enough entries in the ring to dequeue; no object is
+ * dequeued.
+ * if behavior = RTE_RING_QUEUE_VARIABLE
+ * - n: Actual number of objects dequeued.
+ */
+static inline int __attribute__((always_inline))
+__rte_ring_sc_do_dequeue(struct rte_ring *r, void **obj_table,
+ unsigned n, enum rte_ring_queue_behavior behavior)
+{
+ uint32_t cons_head, prod_tail;
+ uint32_t cons_next, entries;
+ unsigned i;
+ uint32_t mask = r->prod.mask;
+
+ cons_head = r->cons.head;
+ prod_tail = r->prod.tail;
+ /* The subtraction is done between two unsigned 32bits value
+ * (the result is always modulo 32 bits even if we have
+ * cons_head > prod_tail). So 'entries' is always between 0
+ * and size(ring)-1. */
+ entries = prod_tail - cons_head;
+
+ if (n > entries) {
+ if (behavior == RTE_RING_QUEUE_FIXED) {
+ __RING_STAT_ADD(r, deq_fail, n);
+ return -ENOENT;
+ }
+ else {
+ if (unlikely(entries == 0)){
+ __RING_STAT_ADD(r, deq_fail, n);
+ return 0;
+ }
+
+ n = entries;
+ }
+ }
+
+ cons_next = cons_head + n;
+ r->cons.head = cons_next;
+
+ /* copy in table */
+ DEQUEUE_PTRS();
+ rte_compiler_barrier();
+
+ __RING_STAT_ADD(r, deq_success, n);
+ r->cons.tail = cons_next;
+ return behavior == RTE_RING_QUEUE_FIXED ? 0 : n;
+}
+
+/**
+ * Enqueue several objects on the ring (multi-producers safe).
+ *
+ * This function uses a "compare and set" instruction to move the
+ * producer index atomically.
+ *
+ * @param r
+ * A pointer to the ring structure.
+ * @param obj_table
+ * A pointer to a table of void * pointers (objects).
+ * @param n
+ * The number of objects to add in the ring from the obj_table.
+ * @return
+ * - 0: Success; objects enqueue.
+ * - -EDQUOT: Quota exceeded. The objects have been enqueued, but the
+ * high water mark is exceeded.
+ * - -ENOBUFS: Not enough room in the ring to enqueue, no object is enqueued.
+ */
+static inline int __attribute__((always_inline))
+rte_ring_mp_enqueue_bulk(struct rte_ring *r, void * const *obj_table,
+ unsigned n)
+{
+ return __rte_ring_mp_do_enqueue(r, obj_table, n, RTE_RING_QUEUE_FIXED);
+}
+
+/**
+ * Enqueue several objects on a ring (NOT multi-producers safe).
+ *
+ * @param r
+ * A pointer to the ring structure.
+ * @param obj_table
+ * A pointer to a table of void * pointers (objects).
+ * @param n
+ * The number of objects to add in the ring from the obj_table.
+ * @return
+ * - 0: Success; objects enqueued.
+ * - -EDQUOT: Quota exceeded. The objects have been enqueued, but the
+ * high water mark is exceeded.
+ * - -ENOBUFS: Not enough room in the ring to enqueue; no object is enqueued.
+ */
+static inline int __attribute__((always_inline))
+rte_ring_sp_enqueue_bulk(struct rte_ring *r, void * const *obj_table,
+ unsigned n)
+{
+ return __rte_ring_sp_do_enqueue(r, obj_table, n, RTE_RING_QUEUE_FIXED);
+}
+