ring: add reset function for flushing

Currently, the flush is done by dequeuing the ring in a while loop. It is
much simpler to flush the queue by resetting the head and tail indices.

Signed-off-by: Gavin Hu <gavin.hu@arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Acked-by: Olivier Matz <olivier.matz@6wind.com>

lib/librte_ring/rte_ring.c

@@ -63,6 +63,13 @@ rte_ring_get_memsize(unsigned count)
 	return sz;
 }
 
+void
+rte_ring_reset(struct rte_ring *r)
+{
+	r->prod.head = r->cons.head = 0;
+	r->prod.tail = r->cons.tail = 0;
+}
+
 int
 rte_ring_init(struct rte_ring *r, const char *name, unsigned count,
 	unsigned flags)

lib/librte_ring/rte_ring.h

@@ -668,6 +668,23 @@ rte_ring_dequeue(struct rte_ring *r, void **obj_p)
 	return rte_ring_dequeue_bulk(r, obj_p, 1, NULL) ? 0 : -ENOENT;
 }
 
+/**
+ * Flush a ring.
+ *
+ * This function flush all the elements in a ring
+ *
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * @warning
+ * Make sure the ring is not in use while calling this function.
+ *
+ * @param r
+ *   A pointer to the ring structure.
+ */
+__rte_experimental
+void
+rte_ring_reset(struct rte_ring *r);
+
 /**
  * Return the number of entries in a ring.
  *

lib/librte_ring/rte_ring_version.map

@@ -17,3 +17,10 @@ DPDK_2.2 {
 	rte_ring_free;
 
 } DPDK_2.0;
+
+EXPERIMENTAL {
+	global:
+
+	rte_ring_reset;
+
+};