ring: allow to initialize without memzone

Allow to initialize a ring in an already allocated memory. The rte_ring_create()
function that allocates a ring in a rte_memzone is still available and now uses
the new rte_ring_init() function in order to factorize the code.

Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>

diff --git a/lib/librte_ring/rte_ring.c b/lib/librte_ring/rte_ring.c
index 156fe49..2eaa6c8 100644 (file)
--- a/lib/librte_ring/rte_ring.c
+++ b/lib/librte_ring/rte_ring.c
@@ -113,18 +113,10 @@ rte_ring_get_memsize(unsigned count)
        return sz;
 }
 
-/* create the ring */
-struct rte_ring *
-rte_ring_create(const char *name, unsigned count, int socket_id,
-               unsigned flags)
+int
+rte_ring_init(struct rte_ring *r, const char *name, unsigned count,
+       unsigned flags)
 {
-       char mz_name[RTE_MEMZONE_NAMESIZE];
-       struct rte_ring *r;
-       const struct rte_memzone *mz;
-       ssize_t ring_size;
-       int mz_flags = 0;
-       struct rte_ring_list* ring_list = NULL;
-
        /* compilation-time checks */
        RTE_BUILD_BUG_ON((sizeof(struct rte_ring) &
                          CACHE_LINE_MASK) != 0);
@@ -141,11 +133,38 @@ rte_ring_create(const char *name, unsigned count, int socket_id,
                          CACHE_LINE_MASK) != 0);
 #endif
 
+       /* init the ring structure */
+       memset(r, 0, sizeof(*r));
+       rte_snprintf(r->name, sizeof(r->name), "%s", name);
+       r->flags = flags;
+       r->prod.watermark = count;
+       r->prod.sp_enqueue = !!(flags & RING_F_SP_ENQ);
+       r->cons.sc_dequeue = !!(flags & RING_F_SC_DEQ);
+       r->prod.size = r->cons.size = count;
+       r->prod.mask = r->cons.mask = count-1;
+       r->prod.head = r->cons.head = 0;
+       r->prod.tail = r->cons.tail = 0;
+
+       return 0;
+}
+
+/* create the ring */
+struct rte_ring *
+rte_ring_create(const char *name, unsigned count, int socket_id,
+               unsigned flags)
+{
+       char mz_name[RTE_MEMZONE_NAMESIZE];
+       struct rte_ring *r;
+       const struct rte_memzone *mz;
+       ssize_t ring_size;
+       int mz_flags = 0;
+       struct rte_ring_list* ring_list = NULL;
+
        /* check that we have an initialised tail queue */
-       if ((ring_list = 
+       if ((ring_list =
             RTE_TAILQ_LOOKUP_BY_IDX(RTE_TAILQ_RING, rte_ring_list)) == NULL) {
                rte_errno = E_RTE_NO_TAILQ;
-               return NULL;    
+               return NULL;
        }
 
        ring_size = rte_ring_get_memsize(count);
@@ -164,26 +183,16 @@ rte_ring_create(const char *name, unsigned count, int socket_id,
        mz = rte_memzone_reserve(mz_name, ring_size, socket_id, mz_flags);
        if (mz != NULL) {
                r = mz->addr;
-
-               /* init the ring structure */
-               memset(r, 0, sizeof(*r));
-               rte_snprintf(r->name, sizeof(r->name), "%s", name);
-               r->flags = flags;
-               r->prod.watermark = count;
-               r->prod.sp_enqueue = !!(flags & RING_F_SP_ENQ);
-               r->cons.sc_dequeue = !!(flags & RING_F_SC_DEQ);
-               r->prod.size = r->cons.size = count;
-               r->prod.mask = r->cons.mask = count-1;
-               r->prod.head = r->cons.head = 0;
-               r->prod.tail = r->cons.tail = 0;
-
+               /* no need to check return value here, we already checked the
+                * arguments above */
+               rte_ring_init(r, name, count, flags);
                TAILQ_INSERT_TAIL(ring_list, r, next);
        } else {
                r = NULL;
                RTE_LOG(ERR, RING, "Cannot reserve memory\n");
        }
        rte_rwlock_write_unlock(RTE_EAL_TAILQ_RWLOCK);
-       
+
        return r;
 }
 

diff --git a/lib/librte_ring/rte_ring.h b/lib/librte_ring/rte_ring.h
index e8493f2..96232d3 100644 (file)
--- a/lib/librte_ring/rte_ring.h
+++ b/lib/librte_ring/rte_ring.h
@@ -214,14 +214,55 @@ struct rte_ring {
  */
 ssize_t rte_ring_get_memsize(unsigned count);
 
+/**
+ * Initialize a ring structure.
+ *
+ * Initialize a ring structure in memory pointed by "r". The size of the
+ * memory area must be large enough to store the ring structure and the
+ * object table. It is advised to use rte_ring_get_memsize() to get the
+ * appropriate size.
+ *
+ * The ring size is set to *count*, which must be a power of two. Water
+ * marking is disabled by default. The real usable ring size is
+ * *count-1* instead of *count* to differentiate a free ring from an
+ * empty ring.
+ *
+ * The ring is not added in RTE_TAILQ_RING global list. Indeed, the
+ * memory given by the caller may not be shareable among dpdk
+ * processes.
+ *
+ * @param r
+ *   The pointer to the ring structure followed by the objects table.
+ * @param name
+ *   The name of the ring.
+ * @param count
+ *   The number of elements in the ring (must be a power of 2).
+ * @param flags
+ *   An OR of the following:
+ *    - RING_F_SP_ENQ: If this flag is set, the default behavior when
+ *      using ``rte_ring_enqueue()`` or ``rte_ring_enqueue_bulk()``
+ *      is "single-producer". Otherwise, it is "multi-producers".
+ *    - RING_F_SC_DEQ: If this flag is set, the default behavior when
+ *      using ``rte_ring_dequeue()`` or ``rte_ring_dequeue_bulk()``
+ *      is "single-consumer". Otherwise, it is "multi-consumers".
+ * @return
+ *   0 on success, or a negative value on error.
+ */
+int rte_ring_init(struct rte_ring *r, const char *name, unsigned count,
+       unsigned flags);
+
 /**
  * Create a new ring named *name* in memory.
  *
- * This function uses ``memzone_reserve()`` to allocate memory. Its size is
- * set to *count*, which must be a power of two. Water marking is
- * disabled by default.
- * Note that the real usable ring size is *count-1* instead of
- * *count*.
+ * This function uses ``memzone_reserve()`` to allocate memory. Then it
+ * calls rte_ring_init() to initialize an empty ring.
+ *
+ * The new ring size is set to *count*, which must be a power of
+ * two. Water marking is disabled by default. The real usable ring size
+ * is *count-1* instead of *count* to differentiate a free ring from an
+ * empty ring.
+ *
+ * The ring is added in RTE_TAILQ_RING list.
  *
  * @param name
  *   The name of the ring.