[dpdk-dev] [PATCH v3] mbuf: extend pktmbuf pool private structure

[Shahaf Shuler <shahafs@mellanox.com>]

With the API and ABI freeze ahead, it will be good to reserve
some bits on the private structure for future use.

Otherwise we will potentially need to maintain two different
private structure during 2020 period.

There is already one use case for those reserved bits[1]

The reserved field should be set to 0 by the user.

[1]
https://patches.dpdk.org/patch/63077/

Signed-off-by: Shahaf Shuler <shahafs@mellanox.com>
---
On v3:
 - use memset to zero the entire private struct
 - validate flags is set to 0 also on ntb example

On v2:
 - rename new field to flags
 - add extra validation in code that flags = 0
---
 examples/ntb/ntb_fwd.c     | 1 +
 lib/librte_mbuf/rte_mbuf.c | 4 +++-
 lib/librte_mbuf/rte_mbuf.h | 1 +
 3 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/examples/ntb/ntb_fwd.c b/examples/ntb/ntb_fwd.c
index edce77ecdc..c914256dd4 100644
--- a/examples/ntb/ntb_fwd.c
+++ b/examples/ntb/ntb_fwd.c
@@ -1256,6 +1256,7 @@ ntb_mbuf_pool_create(uint16_t mbuf_seg_size, uint32_t nb_mbuf,
 	if (mp == NULL)
 		return NULL;
 
+	memset(&mbp_priv, 0, sizeof(mbp_priv));
 	mbp_priv.mbuf_data_room_size = mbuf_seg_size;
 	mbp_priv.mbuf_priv_size = 0;
 	rte_pktmbuf_pool_init(mp, &mbp_priv);
diff --git a/lib/librte_mbuf/rte_mbuf.c b/lib/librte_mbuf/rte_mbuf.c
index 35df1c4c38..8fa7f49645 100644
--- a/lib/librte_mbuf/rte_mbuf.c
+++ b/lib/librte_mbuf/rte_mbuf.c
@@ -49,7 +49,7 @@ rte_pktmbuf_pool_init(struct rte_mempool *mp, void *opaque_arg)
 	/* if no structure is provided, assume no mbuf private area */
 	user_mbp_priv = opaque_arg;
 	if (user_mbp_priv == NULL) {
-		default_mbp_priv.mbuf_priv_size = 0;
+		memset(&default_mbp_priv, 0, sizeof(default_mbp_priv));
 		if (mp->elt_size > sizeof(struct rte_mbuf))
 			roomsz = mp->elt_size - sizeof(struct rte_mbuf);
 		else
@@ -61,6 +61,7 @@ rte_pktmbuf_pool_init(struct rte_mempool *mp, void *opaque_arg)
 	RTE_ASSERT(mp->elt_size >= sizeof(struct rte_mbuf) +
 		user_mbp_priv->mbuf_data_room_size +
 		user_mbp_priv->mbuf_priv_size);
+	RTE_ASSERT(user_mbp_priv->flags == 0);
 
 	mbp_priv = rte_mempool_get_priv(mp);
 	memcpy(mbp_priv, user_mbp_priv, sizeof(*mbp_priv));
@@ -126,6 +127,7 @@ rte_pktmbuf_pool_create_by_ops(const char *name, unsigned int n,
 	}
 	elt_size = sizeof(struct rte_mbuf) + (unsigned)priv_size +
 		(unsigned)data_room_size;
+	memset(&mbp_priv, 0, sizeof(mbp_priv));
 	mbp_priv.mbuf_data_room_size = data_room_size;
 	mbp_priv.mbuf_priv_size = priv_size;
 
diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
index 92d81972ab..219b110b76 100644
--- a/lib/librte_mbuf/rte_mbuf.h
+++ b/lib/librte_mbuf/rte_mbuf.h
@@ -303,6 +303,7 @@ rte_mbuf_to_priv(struct rte_mbuf *m)
 struct rte_pktmbuf_pool_private {
 	uint16_t mbuf_data_room_size; /**< Size of data space in each mbuf. */
 	uint16_t mbuf_priv_size;      /**< Size of private area in each mbuf. */
+	uint32_t flags; /**< reserved for future use. */
 };
 
 #ifdef RTE_LIBRTE_MBUF_DEBUG
-- 
2.12.0