mempool: silence warning on pointer arithmetic

Translating from a mempool object to the mempool pointer does not break
alignment constraints.  However, the compiler is unaware of this fact and
complains on -Wcast-align.  This patch modifies the code to use RTE_PTR_SUB(),
thereby silencing the compiler by casting through (void *).

Signed-off-by: Cyril Chemparathy <cchemparathy@ezchip.com>
Acked-by: Olivier Matz <olivier.matz@6wind.com>

diff --git a/lib/librte_mempool/rte_mempool.c b/lib/librte_mempool/rte_mempool.c
index 3cd5aab..02699a1 100644 (file)
--- a/lib/librte_mempool/rte_mempool.c
+++ b/lib/librte_mempool/rte_mempool.c
@@ -136,7 +136,7 @@ mempool_add_elem(struct rte_mempool *mp, void *obj, uint32_t obj_idx,
        obj = (char *)obj + mp->header_size;
 
        /* set mempool ptr in header */
-       hdr = (struct rte_mempool_objhdr *)((char *)obj - sizeof(*hdr));
+       hdr = RTE_PTR_SUB(obj, sizeof(*hdr));
        hdr->mp = mp;
 
 #ifdef RTE_LIBRTE_MEMPOOL_DEBUG

diff --git a/lib/librte_mempool/rte_mempool.h b/lib/librte_mempool/rte_mempool.h
index f16019a..6d4ce9a 100644 (file)
--- a/lib/librte_mempool/rte_mempool.h
+++ b/lib/librte_mempool/rte_mempool.h
@@ -262,15 +262,13 @@ struct rte_mempool {
 /* return the header of a mempool object (internal) */
 static inline struct rte_mempool_objhdr *__mempool_get_header(void *obj)
 {
-       return (struct rte_mempool_objhdr *)((char *)obj -
-               sizeof(struct rte_mempool_objhdr));
+       return RTE_PTR_SUB(obj, sizeof(struct rte_mempool_objhdr));
 }
 
 /* return the trailer of a mempool object (internal) */
 static inline struct rte_mempool_objtlr *__mempool_get_trailer(void *obj)
 {
-       return (struct rte_mempool_objtlr *)((char *)obj -
-               sizeof(struct rte_mempool_objtlr));
+       return RTE_PTR_SUB(obj, sizeof(struct rte_mempool_objtlr));
 }
 
 /**