env: Add an API to lookup the memory pool created by the primary process

Add spdk_mempool_lookup to lookup the memory pool created by the
primary process. This will be utilized in SPDK multi process
application future.

Signed-off-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Change-Id: I90505b6566dfc93ef5957ef4c73b1a6438c30742
Reviewed-on: https://review.gerrithub.io/c/spdk/spdk/+/459739
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Seth Howell <seth.howell5141@gmail.com>
Reviewed-by: Darek Stojaczyk <dariusz.stojaczyk@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>

CHANGELOG.md

@@ -66,6 +66,9 @@ The parameter `free_space` has been added to spdk_ring_enqueue() to wait when
 the ring is almost full and resume when there is enough space available in
 the ring.
 
+A new API `spdk_mempool_lookup` has been added to lookup the memory pool created
+by the primary process.
+
 ## v19.04:
 
 ### nvme

include/spdk/env.h

@@ -442,6 +442,15 @@ size_t spdk_mempool_count(const struct spdk_mempool *pool);
 uint32_t spdk_mempool_obj_iter(struct spdk_mempool *mp, spdk_mempool_obj_cb_t obj_cb,
 			       void *obj_cb_arg);
 
+/**
+ * Lookup the memory pool identified by the given name.
+ *
+ * \param name Name of the memory pool.
+ *
+ * \return a pointer to the memory pool on success, or NULL on failure.
+ */
+struct spdk_mempool *spdk_mempool_lookup(const char *name);
+
 /**
  * Get the number of dedicated CPU cores utilized by this env abstraction.
  *

lib/env_dpdk/env.c

@@ -296,6 +296,12 @@ spdk_mempool_obj_iter(struct spdk_mempool *mp, spdk_mempool_obj_cb_t obj_cb,
 				    obj_cb_arg);
 }
 
+struct spdk_mempool *
+spdk_mempool_lookup(const char *name)
+{
+	return (struct spdk_mempool *)rte_mempool_lookup(name);
+}
+
 bool
 spdk_process_is_primary(void)
 {