ring: support freeing

When creating a ring, a memzone is created to allocate it in memory,
but the ring could not be freed, as memzones could not be.

Since memzones can be freed now, then rings can be as well,
taking into account if they were initialized using pre-allocated memory
(in which case, memory should be freed externally) or using rte_memzone_reserve
(with rte_ring_create), freeing the memory with rte_memzone_free.

Signed-off-by: Pablo de Lara <pablo.de.lara.guarch@intel.com>
Acked-by: Olivier Matz <olivier.matz@6wind.com>

doc/guides/rel_notes/release_2_2.rst

@@ -4,6 +4,11 @@ DPDK Release 2.2
 New Features
 ------------
 
+* **Enabled freeing of ring.**
+
+  New function rte_ring_free() allows the user to free a ring
+  if it was created with rte_ring_create().
+
 * **Extended Statistics**
 
   Define extended statistics naming scheme to store metadata in the name

lib/librte_ring/rte_ring.c

@@ -1,7 +1,7 @@
 /*-
  *   BSD LICENSE
  *
- *   Copyright(c) 2010-2014 Intel Corporation. All rights reserved.
+ *   Copyright(c) 2010-2015 Intel Corporation. All rights reserved.
  *   All rights reserved.
  *
  *   Redistribution and use in source and binary forms, with or without
@@ -209,6 +209,51 @@ rte_ring_create(const char *name, unsigned count, int socket_id,
 	return r;
 }
 
+/* free the ring */
+void
+rte_ring_free(struct rte_ring *r)
+{
+	struct rte_ring_list *ring_list = NULL;
+	struct rte_tailq_entry *te;
+
+	if (r == NULL)
+		return;
+
+	/*
+	 * Ring was not created with rte_ring_create,
+	 * therefore, there is no memzone to free.
+	 */
+	if (r->memzone == NULL) {
+		RTE_LOG(ERR, RING, "Cannot free ring (not created with rte_ring_create()");
+		return;
+	}
+
+	if (rte_memzone_free(r->memzone) != 0) {
+		RTE_LOG(ERR, RING, "Cannot free memory\n");
+		return;
+	}
+
+	ring_list = RTE_TAILQ_CAST(rte_ring_tailq.head, rte_ring_list);
+	rte_rwlock_write_lock(RTE_EAL_TAILQ_RWLOCK);
+
+	/* find out tailq entry */
+	TAILQ_FOREACH(te, ring_list, next) {
+		if (te->data == (void *) r)
+			break;
+	}
+
+	if (te == NULL) {
+		rte_rwlock_write_unlock(RTE_EAL_TAILQ_RWLOCK);
+		return;
+	}
+
+	TAILQ_REMOVE(ring_list, te, next);
+
+	rte_rwlock_write_unlock(RTE_EAL_TAILQ_RWLOCK);
+
+	rte_free(te);
+}
+
 /*
  * change the high water mark. If *count* is 0, water marking is
  * disabled

lib/librte_ring/rte_ring.h

@@ -304,6 +304,13 @@ int rte_ring_init(struct rte_ring *r, const char *name, unsigned count,
  */
 struct rte_ring *rte_ring_create(const char *name, unsigned count,
 				 int socket_id, unsigned flags);
+/**
+ * De-allocate all memory used by the ring.
+ *
+ * @param r
+ *   Ring to free
+ */
+void rte_ring_free(struct rte_ring *r);
 
 /**
  * Change the high water mark.

lib/librte_ring/rte_ring_version.map

@@ -11,3 +11,10 @@ DPDK_2.0 {
 
 	local: *;
 };
+
+DPDK_2.2 {
+	global:
+
+	rte_ring_free;
+
+} DPDK_2.0;