[dpdk-dev] [PATCH] app: fix refcnt in mbuf allocation

[Thomas Monjalon <thomas.monjalon@6wind.com>]

Hi Dongsu Han,

I think your fix is right.
I've just removed tx_mbuf_alloc() and directly called rte_pktmbuf_alloc() instead.
Is it OK for you ?
Could you also review this (modified) description ?

Thank you

---

From: Dongsu Han <dongsuh at cs.cmu.edu>

test-pmd txonly leaks mbuf from the pool.
The function tx_mbuf_alloc() does not change the refcnt
and the refcnt is 0 when it is first allocated.
However, rte_pktmbuf_free_seg called by the driver's xmit code decrements
reference count to -1. So mbuf never goes back to the pool.
As a result, txonly can't send packets after it exhausts the mempool.

The function tx_mbuf_alloc() was getting mbuf directly from mempool and so
was bypassing mbuf API.
By using the right API, refcnt is correctly handled among other
initializations.

Signed-off-by: Dongsu Han <dongsuh@cs.cmu.edu>
Signed-off-by: Thomas Monjalon <thomas.monjalon@6wind.com>
---
 app/test-pmd/txonly.c |   17 ++---------------
 1 file changed, 2 insertions(+), 15 deletions(-)

diff --git a/app/test-pmd/txonly.c b/app/test-pmd/txonly.c
index d7c8c31..53f7138 100644
--- a/app/test-pmd/txonly.c
+++ b/app/test-pmd/txonly.c
@@ -89,19 +89,6 @@
 static struct ipv4_hdr  pkt_ip_hdr;  /**< IP header of transmitted packets. */
 static struct udp_hdr pkt_udp_hdr; /**< UDP header of transmitted packets. */
 
-static inline struct rte_mbuf *
-tx_mbuf_alloc(struct rte_mempool *mp)
-{
-	struct rte_mbuf *m;
-	void *mb;
-
-	if (rte_mempool_get(mp, &mb) < 0)
-		return NULL;
-	m = (struct rte_mbuf *)mb;
-	__rte_mbuf_sanity_check(m, RTE_MBUF_PKT, 1);
-	return m;
-}
-
 static void
 copy_buf_to_pkt_segs(void* buf, unsigned len, struct rte_mbuf *pkt,
 		     unsigned offset)
@@ -223,7 +210,7 @@ pkt_burst_transmit(struct fwd_stream *fs)
 	vlan_tci = ports[fs->tx_port].tx_vlan_id;
 	ol_flags = ports[fs->tx_port].tx_ol_flags;
 	for (nb_pkt = 0; nb_pkt < nb_pkt_per_burst; nb_pkt++) {
-		pkt = tx_mbuf_alloc(mbp);
+		pkt = rte_pktmbuf_alloc(mbp);
 		if (pkt == NULL) {
 		nomore_mbuf:
 			if (nb_pkt == 0)
@@ -233,7 +220,7 @@ pkt_burst_transmit(struct fwd_stream *fs)
 		pkt->pkt.data_len = tx_pkt_seg_lengths[0];
 		pkt_seg = pkt;
 		for (i = 1; i < tx_pkt_nb_segs; i++) {
-			pkt_seg->pkt.next = tx_mbuf_alloc(mbp);
+			pkt_seg->pkt.next = rte_pktmbuf_alloc(mbp);
 			if (pkt_seg->pkt.next == NULL) {
 				pkt->pkt.nb_segs = i;
 				rte_pktmbuf_free(pkt);
-- 
1.7.10.4