[PATCH v4 2/5] mempool: implement abstract mempool info API

[Andrew Rybchenko <arybchenko@solarflare.com>]

From: "Artem V. Andreev" <Artem.Andreev@oktetlabs.ru>

Primarily, it is intended as a way for the mempool driver to provide
additional information on how it lays up objects inside the mempool.

Signed-off-by: Artem V. Andreev <Artem.Andreev@oktetlabs.ru>
Signed-off-by: Andrew Rybchenko <arybchenko@solarflare.com>
Acked-by: Olivier Matz <olivier.matz@6wind.com>
---
 lib/librte_mempool/rte_mempool.h           | 50 ++++++++++++++++++++++++++++++
 lib/librte_mempool/rte_mempool_ops.c       | 15 +++++++++
 lib/librte_mempool/rte_mempool_version.map |  7 +++++
 3 files changed, 72 insertions(+)

diff --git a/lib/librte_mempool/rte_mempool.h b/lib/librte_mempool/rte_mempool.h
index 3e06ae051..853f2da4d 100644
--- a/lib/librte_mempool/rte_mempool.h
+++ b/lib/librte_mempool/rte_mempool.h
@@ -189,6 +189,23 @@ struct rte_mempool_memhdr {
 	void *opaque;            /**< Argument passed to the free callback */
 };
 
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice.
+ *
+ * Additional information about the mempool
+ *
+ * The structure is cache-line aligned to avoid ABI breakages in
+ * a number of cases when something small is added.
+ */
+struct rte_mempool_info {
+	/*
+	 * Dummy structure member to make it non emtpy until the first
+	 * real member is added.
+	 */
+	unsigned int dummy;
+} __rte_cache_aligned;
+
 /**
  * The RTE mempool structure.
  */
@@ -499,6 +516,16 @@ int rte_mempool_op_populate_default(struct rte_mempool *mp,
 		void *vaddr, rte_iova_t iova, size_t len,
 		rte_mempool_populate_obj_cb_t *obj_cb, void *obj_cb_arg);
 
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice.
+ *
+ * Get some additional information about a mempool.
+ */
+typedef int (*rte_mempool_get_info_t)(const struct rte_mempool *mp,
+		struct rte_mempool_info *info);
+
+
 /** Structure defining mempool operations structure */
 struct rte_mempool_ops {
 	char name[RTE_MEMPOOL_OPS_NAMESIZE]; /**< Name of mempool ops struct. */
@@ -517,6 +544,10 @@ struct rte_mempool_ops {
 	 * provided memory chunk.
 	 */
 	rte_mempool_populate_t populate;
+	/**
+	 * Get mempool info
+	 */
+	rte_mempool_get_info_t get_info;
 } __rte_cache_aligned;
 
 #define RTE_MEMPOOL_MAX_OPS_IDX 16  /**< Max registered ops structs */
@@ -679,6 +710,25 @@ int rte_mempool_ops_populate(struct rte_mempool *mp, unsigned int max_objs,
 			     rte_mempool_populate_obj_cb_t *obj_cb,
 			     void *obj_cb_arg);
 
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice.
+ *
+ * Wrapper for mempool_ops get_info callback.
+ *
+ * @param[in] mp
+ *   Pointer to the memory pool.
+ * @param[out] info
+ *   Pointer to the rte_mempool_info structure
+ * @return
+ *   - 0: Success; The mempool driver supports retrieving supplementary
+ *        mempool information
+ *   - -ENOTSUP - doesn't support get_info ops (valid case).
+ */
+__rte_experimental
+int rte_mempool_ops_get_info(const struct rte_mempool *mp,
+			 struct rte_mempool_info *info);
+
 /**
  * @internal wrapper for mempool_ops free callback.
  *
diff --git a/lib/librte_mempool/rte_mempool_ops.c b/lib/librte_mempool/rte_mempool_ops.c
index ea9be1eb2..efc1c084c 100644
--- a/lib/librte_mempool/rte_mempool_ops.c
+++ b/lib/librte_mempool/rte_mempool_ops.c
@@ -59,6 +59,7 @@ rte_mempool_register_ops(const struct rte_mempool_ops *h)
 	ops->get_count = h->get_count;
 	ops->calc_mem_size = h->calc_mem_size;
 	ops->populate = h->populate;
+	ops->get_info = h->get_info;
 
 	rte_spinlock_unlock(&rte_mempool_ops_table.sl);
 
@@ -134,6 +135,20 @@ rte_mempool_ops_populate(struct rte_mempool *mp, unsigned int max_objs,
 			     obj_cb_arg);
 }
 
+/* wrapper to get additional mempool info */
+int
+rte_mempool_ops_get_info(const struct rte_mempool *mp,
+			 struct rte_mempool_info *info)
+{
+	struct rte_mempool_ops *ops;
+
+	ops = rte_mempool_get_ops(mp->ops_index);
+
+	RTE_FUNC_PTR_OR_ERR_RET(ops->get_info, -ENOTSUP);
+	return ops->get_info(mp, info);
+}
+
+
 /* sets mempool ops previously registered by rte_mempool_register_ops. */
 int
 rte_mempool_set_ops_byname(struct rte_mempool *mp, const char *name,
diff --git a/lib/librte_mempool/rte_mempool_version.map b/lib/librte_mempool/rte_mempool_version.map
index cf375dbe6..c9d16ecc4 100644
--- a/lib/librte_mempool/rte_mempool_version.map
+++ b/lib/librte_mempool/rte_mempool_version.map
@@ -57,3 +57,10 @@ DPDK_18.05 {
 	rte_mempool_op_populate_default;
 
 } DPDK_17.11;
+
+EXPERIMENTAL {
+	global:
+
+	rte_mempool_ops_get_info;
+
+} DPDK_18.05;
-- 
2.14.1