[dpdk-dev] [PATCH 2/3] mempool: introduce objtlr structure for object trailers

[Olivier Matz <olivier.matz@6wind.com>]

Each object stored in mempools are suffixed by a trailer, storing
a cookie in debug mode which help to detect memory corruptions.

Like for headers, introduce a structure that materializes the content of
this trailer.

Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
---
 lib/librte_mempool/rte_mempool.c |  4 +++-
 lib/librte_mempool/rte_mempool.h | 42 +++++++++++++++++++++-------------------
 2 files changed, 25 insertions(+), 21 deletions(-)

diff --git a/lib/librte_mempool/rte_mempool.c b/lib/librte_mempool/rte_mempool.c
index b2d8700..60369cf 100644
--- a/lib/librte_mempool/rte_mempool.c
+++ b/lib/librte_mempool/rte_mempool.c
@@ -131,6 +131,7 @@ mempool_add_elem(struct rte_mempool *mp, void *obj, uint32_t obj_idx,
 	rte_mempool_obj_ctor_t *obj_init, void *obj_init_arg)
 {
 	struct rte_mempool_objhdr *hdr;
+	struct rte_mempool_objtlr *tlr __rte_unused;
 
 	obj = (char *)obj + mp->header_size;
 
@@ -140,7 +141,8 @@ mempool_add_elem(struct rte_mempool *mp, void *obj, uint32_t obj_idx,
 
 #ifdef RTE_LIBRTE_MEMPOOL_DEBUG
 	hdr->cookie = RTE_MEMPOOL_HEADER_COOKIE2;
-	__mempool_write_trailer_cookie(obj);
+	tlr = __mempool_get_trailer(obj);
+	tlr->cookie = RTE_MEMPOOL_TRAILER_COOKIE;
 #endif
 	/* call the initializer */
 	if (obj_init)
diff --git a/lib/librte_mempool/rte_mempool.h b/lib/librte_mempool/rte_mempool.h
index 5058940..cdb8f67 100644
--- a/lib/librte_mempool/rte_mempool.h
+++ b/lib/librte_mempool/rte_mempool.h
@@ -155,6 +155,18 @@ struct rte_mempool_objhdr {
 };
 
 /**
+ * Mempool object trailer structure
+ *
+ * In debug mode, each object stored in mempools are suffixed by this
+ * trailer structure containing a cookie preventing memory corruptions.
+ */
+struct rte_mempool_objtlr {
+#ifdef RTE_LIBRTE_MEMPOOL_DEBUG
+	uint64_t cookie;                 /**< Debug cookie. */
+#endif
+};
+
+/**
  * The RTE mempool structure.
  */
 struct rte_mempool {
@@ -249,6 +261,13 @@ static inline struct rte_mempool_objhdr *__mempool_get_header(void *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 a pointer to the mempool owning this object.
  *
@@ -264,25 +283,6 @@ static inline struct rte_mempool *rte_mempool_from_obj(void *obj)
 	return hdr->mp;
 }
 
-#ifdef RTE_LIBRTE_MEMPOOL_DEBUG
-/* get trailer cookie value */
-static inline uint64_t __mempool_read_trailer_cookie(void *obj)
-{
-	struct rte_mempool **mpp = __mempool_from_obj(obj);
-	return *(uint64_t *)((char *)obj + (*mpp)->elt_size);
-
-}
-
-/* write trailer cookie value */
-static inline void __mempool_write_trailer_cookie(void *obj)
-{
-	uint64_t *cookie_p;
-	struct rte_mempool **mpp = __mempool_from_obj(obj);
-	cookie_p = (uint64_t *)((char *)obj + (*mpp)->elt_size);
-	*cookie_p = RTE_MEMPOOL_TRAILER_COOKIE;
-}
-#endif /* RTE_LIBRTE_MEMPOOL_DEBUG */
-
 /**
  * @internal Check and update cookies or panic.
  *
@@ -306,6 +306,7 @@ static inline void __mempool_check_cookies(const struct rte_mempool *mp,
 					   unsigned n, int free)
 {
 	struct rte_mempool_objhdr *hdr;
+	struct rte_mempool_objtlr *tlr;
 	uint64_t cookie;
 	void *tmp;
 	void *obj;
@@ -356,7 +357,8 @@ static inline void __mempool_check_cookies(const struct rte_mempool *mp,
 				rte_panic("MEMPOOL: bad header cookie (audit)\n");
 			}
 		}
-		cookie = __mempool_read_trailer_cookie(obj);
+		tlr = __mempool_get_trailer(obj);
+		cookie = tlr->cookie;
 		if (cookie != RTE_MEMPOOL_TRAILER_COOKIE) {
 			rte_log_set_history(0);
 			RTE_LOG(CRIT, MEMPOOL,
-- 
2.1.4