[ovs-dev] [PATCH v12 3/3] dp-packet: Fix allocated size on DPDK init.

[Tiago Lam]

When enabled with DPDK OvS deals with two types of packets, the ones
coming from the mempool and the ones locally created by OvS - which are
copied to mempool mbufs before output. In the latter, the space is
allocated from the system, while in the former the mbufs are allocated
from a mempool, which takes care of initialising them appropriately.

In the current implementation, during mempool's initialisation of mbufs,
dp_packet_set_allocated() is called from dp_packet_init_dpdk() without
considering that the allocated space, in the case of multi-segment
mbufs, might be greater than a single mbuf.  Furthermore, given that
dp_packet_init_dpdk() is on the code path that's called upon mempool's
initialisation, a call to dp_packet_set_allocated() is redundant, since
mempool takes care of initialising it.

To fix this, dp_packet_set_allocated() is no longer called after
initialisation of a mempool, only in dp_packet_init__(), which is still
called by OvS when initialising locally created packets.

Signed-off-by: Tiago Lam <tiago.lam at intel.com>
Acked-by: Eelco Chaudron <echaudro at redhat.com>
Acked-by: Flavio Leitner <fbl at sysclose.org>
---
 lib/dp-packet.c   | 11 +++--------
 lib/dp-packet.h   |  2 +-
 lib/netdev-dpdk.c |  2 +-
 3 files changed, 5 insertions(+), 10 deletions(-)

diff --git a/lib/dp-packet.c b/lib/dp-packet.c
index 443c225..93b0e9c 100644
--- a/lib/dp-packet.c
+++ b/lib/dp-packet.c
@@ -92,16 +92,11 @@ dp_packet_use_const(struct dp_packet *b, const void *data, size_t size)
     dp_packet_set_size(b, size);
 }
 
-/* Initializes 'b' as an empty dp_packet that contains the 'allocated' bytes.
- * DPDK allocated dp_packet and *data is allocated from one continous memory
- * region as part of memory pool, so in memory data start right after
- * dp_packet.  Therefore, there is a special method to free this type of
- * buffer.  Here, non-transient ovs dp-packet fields are initialized for
- * packets that are part of a DPDK memory pool. */
+/* Initializes 'b' as a DPDK dp-packet, which must have been allocated from a
+ * DPDK memory pool. */
 void
-dp_packet_init_dpdk(struct dp_packet *b, size_t allocated)
+dp_packet_init_dpdk(struct dp_packet *b)
 {
-    dp_packet_set_allocated(b, allocated);
     b->source = DPBUF_DPDK;
 }
 
diff --git a/lib/dp-packet.h b/lib/dp-packet.h
index fe34d04..7b85dd9 100644
--- a/lib/dp-packet.h
+++ b/lib/dp-packet.h
@@ -114,7 +114,7 @@ void dp_packet_use(struct dp_packet *, void *, size_t);
 void dp_packet_use_stub(struct dp_packet *, void *, size_t);
 void dp_packet_use_const(struct dp_packet *, const void *, size_t);
 
-void dp_packet_init_dpdk(struct dp_packet *, size_t allocated);
+void dp_packet_init_dpdk(struct dp_packet *);
 
 void dp_packet_init(struct dp_packet *, size_t);
 void dp_packet_uninit(struct dp_packet *);
diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c
index a72438a..ff88331 100644
--- a/lib/netdev-dpdk.c
+++ b/lib/netdev-dpdk.c
@@ -550,7 +550,7 @@ ovs_rte_pktmbuf_init(struct rte_mempool *mp OVS_UNUSED,
 {
     struct rte_mbuf *pkt = _p;
 
-    dp_packet_init_dpdk((struct dp_packet *) pkt, pkt->buf_len);
+    dp_packet_init_dpdk((struct dp_packet *) pkt);
 }
 
 static int
-- 
2.7.4