[PATCH 02/36] mempool: replace elt_size by total_elt_size

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

In some mempool functions, we use the size of the elements as arguments or in
variables. There is a confusion between the size including or not including
the header and trailer.

To avoid this confusion:
- update the API documentation
- rename the variables and argument names as "elt_size" when the size does not
  include the header and trailer, or else as "total_elt_size".

Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
---
 lib/librte_mempool/rte_mempool.c | 21 +++++++++++----------
 lib/librte_mempool/rte_mempool.h | 19 +++++++++++--------
 2 files changed, 22 insertions(+), 18 deletions(-)

diff --git a/lib/librte_mempool/rte_mempool.c b/lib/librte_mempool/rte_mempool.c
index ce78476..90b5b1b 100644
--- a/lib/librte_mempool/rte_mempool.c
+++ b/lib/librte_mempool/rte_mempool.c
@@ -156,13 +156,13 @@ mempool_add_elem(struct rte_mempool *mp, void *obj, uint32_t obj_idx,
  *
  * Given the pointer to the memory, and its topology in physical memory
  * (the physical addresses table), iterate through the "elt_num" objects
- * of size "total_elt_sz" aligned at "align". For each object in this memory
+ * of size "elt_sz" aligned at "align". For each object in this memory
  * chunk, invoke a callback. It returns the effective number of objects
  * in this memory. */
 uint32_t
-rte_mempool_obj_iter(void *vaddr, uint32_t elt_num, size_t elt_sz, size_t align,
-	const phys_addr_t paddr[], uint32_t pg_num, uint32_t pg_shift,
-	rte_mempool_obj_iter_t obj_iter, void *obj_iter_arg)
+rte_mempool_obj_iter(void *vaddr, uint32_t elt_num, size_t total_elt_sz,
+	size_t align, const phys_addr_t paddr[], uint32_t pg_num,
+	uint32_t pg_shift, rte_mempool_obj_iter_t obj_iter, void *obj_iter_arg)
 {
 	uint32_t i, j, k;
 	uint32_t pgn, pgf;
@@ -178,7 +178,7 @@ rte_mempool_obj_iter(void *vaddr, uint32_t elt_num, size_t elt_sz, size_t align,
 	while (i != elt_num && j != pg_num) {
 
 		start = RTE_ALIGN_CEIL(va, align);
-		end = start + elt_sz;
+		end = start + total_elt_sz;
 
 		/* index of the first page for the next element. */
 		pgf = (end >> pg_shift) - (start >> pg_shift);
@@ -255,6 +255,7 @@ mempool_populate(struct rte_mempool *mp, size_t num, size_t align,
 		mempool_obj_populate, &arg);
 }
 
+/* get the header, trailer and total size of a mempool element. */
 uint32_t
 rte_mempool_calc_obj_size(uint32_t elt_size, uint32_t flags,
 	struct rte_mempool_objsz *sz)
@@ -332,17 +333,17 @@ rte_mempool_calc_obj_size(uint32_t elt_size, uint32_t flags,
  * Calculate maximum amount of memory required to store given number of objects.
  */
 size_t
-rte_mempool_xmem_size(uint32_t elt_num, size_t elt_sz, uint32_t pg_shift)
+rte_mempool_xmem_size(uint32_t elt_num, size_t total_elt_sz, uint32_t pg_shift)
 {
 	size_t n, pg_num, pg_sz, sz;
 
 	pg_sz = (size_t)1 << pg_shift;
 
-	if ((n = pg_sz / elt_sz) > 0) {
+	if ((n = pg_sz / total_elt_sz) > 0) {
 		pg_num = (elt_num + n - 1) / n;
 		sz = pg_num << pg_shift;
 	} else {
-		sz = RTE_ALIGN_CEIL(elt_sz, pg_sz) * elt_num;
+		sz = RTE_ALIGN_CEIL(total_elt_sz, pg_sz) * elt_num;
 	}
 
 	return sz;
@@ -362,7 +363,7 @@ mempool_lelem_iter(void *arg, __rte_unused void *start, void *end,
  * given memory footprint to store required number of elements.
  */
 ssize_t
-rte_mempool_xmem_usage(void *vaddr, uint32_t elt_num, size_t elt_sz,
+rte_mempool_xmem_usage(void *vaddr, uint32_t elt_num, size_t total_elt_sz,
 	const phys_addr_t paddr[], uint32_t pg_num, uint32_t pg_shift)
 {
 	uint32_t n;
@@ -373,7 +374,7 @@ rte_mempool_xmem_usage(void *vaddr, uint32_t elt_num, size_t elt_sz,
 	va = (uintptr_t)vaddr;
 	uv = va;
 
-	if ((n = rte_mempool_obj_iter(vaddr, elt_num, elt_sz, 1,
+	if ((n = rte_mempool_obj_iter(vaddr, elt_num, total_elt_sz, 1,
 			paddr, pg_num, pg_shift, mempool_lelem_iter,
 			&uv)) != elt_num) {
 		return -(ssize_t)n;
diff --git a/lib/librte_mempool/rte_mempool.h b/lib/librte_mempool/rte_mempool.h
index bd78df5..ca4657f 100644
--- a/lib/librte_mempool/rte_mempool.h
+++ b/lib/librte_mempool/rte_mempool.h
@@ -1289,7 +1289,7 @@ struct rte_mempool *rte_mempool_lookup(const char *name);
  * calculates header, trailer, body and total sizes of the mempool object.
  *
  * @param elt_size
- *   The size of each element.
+ *   The size of each element, without header and trailer.
  * @param flags
  *   The flags used for the mempool creation.
  *   Consult rte_mempool_create() for more information about possible values.
@@ -1315,14 +1315,15 @@ uint32_t rte_mempool_calc_obj_size(uint32_t elt_size, uint32_t flags,
  *
  * @param elt_num
  *   Number of elements.
- * @param elt_sz
- *   The size of each element.
+ * @param total_elt_sz
+ *   The size of each element, including header and trailer, as returned
+ *   by rte_mempool_calc_obj_size().
  * @param pg_shift
  *   LOG2 of the physical pages size.
  * @return
  *   Required memory size aligned at page boundary.
  */
-size_t rte_mempool_xmem_size(uint32_t elt_num, size_t elt_sz,
+size_t rte_mempool_xmem_size(uint32_t elt_num, size_t total_elt_sz,
 	uint32_t pg_shift);
 
 /**
@@ -1336,8 +1337,9 @@ size_t rte_mempool_xmem_size(uint32_t elt_num, size_t elt_sz,
  *   Will be used to store mempool objects.
  * @param elt_num
  *   Number of elements.
- * @param elt_sz
- *   The size of each element.
+ * @param total_elt_sz
+ *   The size of each element, including header and trailer, as returned
+ *   by rte_mempool_calc_obj_size().
  * @param paddr
  *   Array of physical addresses of the pages that comprises given memory
  *   buffer.
@@ -1351,8 +1353,9 @@ size_t rte_mempool_xmem_size(uint32_t elt_num, size_t elt_sz,
  *   buffer is too small, return a negative value whose absolute value
  *   is the actual number of elements that can be stored in that buffer.
  */
-ssize_t rte_mempool_xmem_usage(void *vaddr, uint32_t elt_num, size_t elt_sz,
-	const phys_addr_t paddr[], uint32_t pg_num, uint32_t pg_shift);
+ssize_t rte_mempool_xmem_usage(void *vaddr, uint32_t elt_num,
+	size_t total_elt_sz, const phys_addr_t paddr[], uint32_t pg_num,
+	uint32_t pg_shift);
 
 /**
  * Walk list of all memory pools
-- 
2.1.4