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

Thomas Monjalon thomas.monjalon at 6wind.com
Mon May 6 18:00:01 CEST 2013


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.
The dedicated function is rte_pktmbuf_alloc() but it is much slower because
it does unnecessary initializations in rte_pktmbuf_reset().
By using the internal API __rte_mbuf_raw_alloc(), refcnt is correctly handled
without adding too much overload.

Signed-off-by: Dongsu Han <dongsuh at cs.cmu.edu>
Signed-off-by: Thomas Monjalon <thomas.monjalon at 6wind.com>
---
 app/test-pmd/txonly.c |    5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/app/test-pmd/txonly.c b/app/test-pmd/txonly.c
index d7c8c31..e7c9a1a 100644
--- a/app/test-pmd/txonly.c
+++ b/app/test-pmd/txonly.c
@@ -93,11 +93,8 @@ 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;
+	m = __rte_mbuf_raw_alloc(mp);
 	__rte_mbuf_sanity_check(m, RTE_MBUF_PKT, 1);
 	return m;
 }
-- 
1.7.10.4



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