[dpdk-dev] [PATCH] kni: fix wrong mbuf alloc count in kni_allocate_mbufs

[wangyunjian]

From: Yunjian Wang <wangyunjian at huawei.com>

In kni_allocate_mbufs(), we alloc mbuf for alloc_q as this code.
allocq_free = (kni->alloc_q->read - kni->alloc_q->write - 1) \
		& (MAX_MBUF_BURST_NUM - 1);
The value of allocq_free maybe zero (e.g 32 & (32 - 1) = 0), and
it will not fill the alloc_q. When the alloc_q's free count is
zero, it will drop the packet in kernel kni.

In this patch, we set the allocq_free as the min between
MAX_MBUF_BURST_NUM and the free count of the alloc_q.

Signed-off-by: Cheng Liu <liucheng11 at huawei.com>
Signed-off-by: Yunjian Wang <wangyunjian at huawei.com>
---
 lib/kni/rte_kni.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/lib/kni/rte_kni.c b/lib/kni/rte_kni.c
index 9dae6a8d7c..20d8f20cef 100644
--- a/lib/kni/rte_kni.c
+++ b/lib/kni/rte_kni.c
@@ -677,8 +677,9 @@ kni_allocate_mbufs(struct rte_kni *kni)
 		return;
 	}
 
-	allocq_free = (kni->alloc_q->read - kni->alloc_q->write - 1)
-			& (MAX_MBUF_BURST_NUM - 1);
+	allocq_free = kni_fifo_free_count(kni->alloc_q);
+	allocq_free = (allocq_free > MAX_MBUF_BURST_NUM) ?
+		      MAX_MBUF_BURST_NUM : allocq_free;
 	for (i = 0; i < allocq_free; i++) {
 		pkts[i] = rte_pktmbuf_alloc(kni->pktmbuf_pool);
 		if (unlikely(pkts[i] == NULL)) {
-- 
2.23.0