[dpdk-dev] [PATCH] virito: fix reuse index in nested loop

[Jianfeng Tan]

This patches fixes problem of reusing index of outmost loop in nested
loops. This bug will lead to failure when starting a multi queue
virtio device: rx queues (except from the first one) cannot be started,
expecially their vq_ring cannot be initialized, so that when invoking
rx func on these queues, segment fault happens.

Fixes: a900472aedef ("virtio: split virtio Rx/Tx queue")

Signed-off-by: Jianfeng Tan <jianfeng.tan at intel.com>
---
 drivers/net/virtio/virtio_rxtx.c | 36 ++++++++++++++++++++----------------
 1 file changed, 20 insertions(+), 16 deletions(-)

diff --git a/drivers/net/virtio/virtio_rxtx.c b/drivers/net/virtio/virtio_rxtx.c
index 2e7205b..b96d0cb 100644
--- a/drivers/net/virtio/virtio_rxtx.c
+++ b/drivers/net/virtio/virtio_rxtx.c
@@ -331,7 +331,7 @@ virtio_dev_rxtx_start(struct rte_eth_dev *dev)
         * -    Allocate blank mbufs for the each rx descriptor
         *
         */
-       int i;
+       int i, j;

        PMD_INIT_FUNC_TRACE();

@@ -352,15 +352,18 @@ virtio_dev_rxtx_start(struct rte_eth_dev *dev)
                error = ENOSPC;

 #ifdef RTE_MACHINE_CPUFLAG_SSSE3
-               if (use_simple_rxtx)
-                       for (i = 0; i < vq->vq_nentries; i++) {
-                               vq->vq_ring.avail->ring[i] = i;
-                               vq->vq_ring.desc[i].flags = VRING_DESC_F_WRITE;
+               if (use_simple_rxtx) {
+                       uint16_t k;
+
+                       for (k = 0; k < vq->vq_nentries; k++) {
+                               vq->vq_ring.avail->ring[k] = k;
+                               vq->vq_ring.desc[k].flags = VRING_DESC_F_WRITE;
                        }
+               }
 #endif
                memset(&rxvq->fake_mbuf, 0, sizeof(rxvq->fake_mbuf));
-               for (i = 0; i < RTE_PMD_VIRTIO_RX_MAX_BURST; i++)
-                       vq->sw_ring[vq->vq_nentries + i] = &rxvq->fake_mbuf;
+               for (j = 0; j < RTE_PMD_VIRTIO_RX_MAX_BURST; j++)
+                       vq->sw_ring[vq->vq_nentries + j] = &rxvq->fake_mbuf;

                while (!virtqueue_full(vq)) {
                        m = rte_mbuf_raw_alloc(rxvq->mpool);
@@ -399,20 +402,21 @@ virtio_dev_rxtx_start(struct rte_eth_dev *dev)
 #ifdef RTE_MACHINE_CPUFLAG_SSSE3
                if (use_simple_rxtx) {
                        int mid_idx  = vq->vq_nentries >> 1;
-                       for (i = 0; i < mid_idx; i++) {
-                               vq->vq_ring.avail->ring[i] = i + mid_idx;
-                               vq->vq_ring.desc[i + mid_idx].next = i;
-                               vq->vq_ring.desc[i + mid_idx].addr =
+
+                       for (j = 0; j < mid_idx; j++) {
+                               vq->vq_ring.avail->ring[j] = j + mid_idx;
+                               vq->vq_ring.desc[j + mid_idx].next = j;
+                               vq->vq_ring.desc[j + mid_idx].addr =
                                        txvq->virtio_net_hdr_mem +
                                        offsetof(struct virtio_tx_region, 
tx_hdr);
-                               vq->vq_ring.desc[i + mid_idx].len =
+                               vq->vq_ring.desc[j + mid_idx].len =
                                        vq->hw->vtnet_hdr_size;
-                               vq->vq_ring.desc[i + mid_idx].flags =
+                               vq->vq_ring.desc[j + mid_idx].flags =
                                        VRING_DESC_F_NEXT;
-                               vq->vq_ring.desc[i].flags = 0;
+                               vq->vq_ring.desc[j].flags = 0;
                        }
-                       for (i = mid_idx; i < vq->vq_nentries; i++)
-                               vq->vq_ring.avail->ring[i] = i;
+                       for (j = mid_idx; j < vq->vq_nentries; j++)
+                               vq->vq_ring.avail->ring[j] = j;
                }
 #endif
                VIRTQUEUE_DUMP(vq);
-- 
2.1.4