[dpdk-dev] [PATCH v3 2/2] mbuf: better document usage of packet pool initializers

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

Clarify that the mempool private initializer and object initializer used
for packet pools require that the mempool private size is large enough.

Also add an assert (only enabled when -DRTE_ENABLE_ASSERT is passed) to
check this constraint.

Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
---
 lib/mbuf/rte_mbuf.c | 5 +++++
 lib/mbuf/rte_mbuf.h | 8 +++++++-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/lib/mbuf/rte_mbuf.c b/lib/mbuf/rte_mbuf.c
index 3ff0a69187..f7e3c1a187 100644
--- a/lib/mbuf/rte_mbuf.c
+++ b/lib/mbuf/rte_mbuf.c
@@ -43,6 +43,8 @@ rte_pktmbuf_pool_init(struct rte_mempool *mp, void *opaque_arg)
 	struct rte_pktmbuf_pool_private default_mbp_priv;
 	uint16_t roomsz;
 
+	RTE_ASSERT(mp->private_data_size >=
+		   sizeof(struct rte_pktmbuf_pool_private));
 	RTE_ASSERT(mp->elt_size >= sizeof(struct rte_mbuf));
 
 	/* if no structure is provided, assume no mbuf private area */
@@ -83,6 +85,9 @@ rte_pktmbuf_init(struct rte_mempool *mp,
 	struct rte_mbuf *m = _m;
 	uint32_t mbuf_size, buf_len, priv_size;
 
+	RTE_ASSERT(mp->private_data_size >=
+		   sizeof(struct rte_pktmbuf_pool_private));
+
 	priv_size = rte_pktmbuf_priv_size(mp);
 	mbuf_size = sizeof(struct rte_mbuf) + priv_size;
 	buf_len = rte_pktmbuf_data_room_size(mp);
diff --git a/lib/mbuf/rte_mbuf.h b/lib/mbuf/rte_mbuf.h
index c4c9ebfaa0..a555f216ae 100644
--- a/lib/mbuf/rte_mbuf.h
+++ b/lib/mbuf/rte_mbuf.h
@@ -624,6 +624,9 @@ rte_mbuf_raw_free(struct rte_mbuf *m)
  * address, and so on). This function is given as a callback function to
  * rte_mempool_obj_iter() or rte_mempool_create() at pool creation time.
  *
+ * This function expects that the mempool private area was previously
+ * initialized with rte_pktmbuf_pool_init().
+ *
  * @param mp
  *   The mempool from which mbufs originate.
  * @param opaque_arg
@@ -639,7 +642,7 @@ void rte_pktmbuf_init(struct rte_mempool *mp, void *opaque_arg,
 		      void *m, unsigned i);
 
 /**
- * A  packet mbuf pool constructor.
+ * A packet mbuf pool constructor.
  *
  * This function initializes the mempool private data in the case of a
  * pktmbuf pool. This private data is needed by the driver. The
@@ -648,6 +651,9 @@ void rte_pktmbuf_init(struct rte_mempool *mp, void *opaque_arg,
  * pool creation. It can be extended by the user, for example, to
  * provide another packet size.
  *
+ * The mempool private area size must be at least equal to
+ * sizeof(struct rte_pktmbuf_pool_private).
+ *
  * @param mp
  *   The mempool from which mbufs originate.
  * @param opaque_arg
-- 
2.29.2