[dpdk-dev] [PATCH v4 1/9] mempool: silence -Wcast-align on pointer arithmetic

[Cyril Chemparathy <cchemparathy@ezchip.com>]

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 *).

Change-Id: I4a67c9aa1bf012a0bf860d21bb8105db89062c76
Signed-off-by: Cyril Chemparathy <cchemparathy@ezchip.com>
---
 lib/librte_mempool/rte_mempool.c | 2 +-
 lib/librte_mempool/rte_mempool.h | 6 ++----
 2 files changed, 3 insertions(+), 5 deletions(-)

diff --git a/lib/librte_mempool/rte_mempool.c b/lib/librte_mempool/rte_mempool.c
index f592dc7..002d3a8 100644
--- 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 a8054e1..380d60b 100644
--- 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));
 }
 
 /**
-- 
2.1.2