From: Balazs Nemeth <bnemeth@redhat.com>
To: bnemeth@redhat.com, dev@dpdk.org, weix.ling@intel.com
Subject: [dpdk-dev] [PATCH] vhost: fix invalid use of stored last used index
Date: Fri, 14 May 2021 18:02:07 +0200 [thread overview]
Message-ID: <83fa6253725a7bc69bccb7897f380422354a2898.1621008025.git.bnemeth@redhat.com> (raw)
The optimization introduced by commit d18db8049c7c ("vhost: read last
used index once") didn't account for the fact that
vhost_flush_enqueue_shadow_packed increments the last_used_idx. For this
reason, store last_used_idx after the potential call to
vhost_flush_enqueue_shadow_packed.
Fixes: d18db8049c7c ("vhost: read last used index once")
Signed-off-by: Balazs Nemeth <bnemeth@redhat.com>
---
lib/vhost/virtio_net.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/lib/vhost/virtio_net.c b/lib/vhost/virtio_net.c
index abfd67d38c..8da8a86a10 100644
--- a/lib/vhost/virtio_net.c
+++ b/lib/vhost/virtio_net.c
@@ -218,14 +218,17 @@ vhost_flush_enqueue_batch_packed(struct virtio_net *dev,
{
uint16_t i;
uint16_t flags;
- uint16_t last_used_idx = vq->last_used_idx;
- struct vring_packed_desc *desc_base = &vq->desc_packed[last_used_idx];
+ uint16_t last_used_idx;
+ struct vring_packed_desc *desc_base;
if (vq->shadow_used_idx) {
do_data_copy_enqueue(dev, vq);
vhost_flush_enqueue_shadow_packed(dev, vq);
}
+ last_used_idx = vq->last_used_idx;
+ desc_base = &vq->desc_packed[last_used_idx];
+
flags = PACKED_DESC_ENQUEUE_USED_FLAG(vq->used_wrap_counter);
vhost_for_each_try_unroll(i, 0, PACKED_BATCH_SIZE) {
--
2.30.2
next reply other threads:[~2021-05-14 16:02 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-14 16:02 Balazs Nemeth [this message]
2021-05-15 6:10 ` [dpdk-dev] [PATCH] vhost: fix invalid use of stored last used index David Marchand
2021-05-17 7:37 ` Maxime Coquelin
2021-05-17 10:07 ` Ling, WeiX
2021-05-17 10:46 ` Maxime Coquelin
2021-05-18 8:03 ` Xia, Chenbo
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