Kernel/linux-next
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git synced 2025-01-01 10:42:11 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

virtio_ring: Avoid loop when vq is broken in virtqueue_poll

Browse Source 
The loop may exist if vq->broken is true,
virtqueue_get_buf_ctx_packed or virtqueue_get_buf_ctx_split
will return NULL, so virtnet_poll will reschedule napi to
receive packet, it will lead cpu usage(si) to 100%.

call trace as below:
virtnet_poll
	virtnet_receive
		virtqueue_get_buf_ctx
			virtqueue_get_buf_ctx_packed
			virtqueue_get_buf_ctx_split
	virtqueue_napi_complete
		virtqueue_poll           //return true
		virtqueue_napi_schedule //it will reschedule napi

to fix this, return false if vq is broken in virtqueue_poll.

Signed-off-by: Mao Wenan <wenan.mao@linux.alibaba.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Link: https://lore.kernel.org/r/1596354249-96204-1-git-send-email-wenan.mao@linux.alibaba.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
This commit is contained in:
Mao Wenan 2020-08-02 15:44:09 +08:00 committed by Michael S. Tsirkin
parent 64ffa39dc8
commit 481a0d7422
1 changed files with 3 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
drivers/virtio/virtio_ring.c
View File

@ -1960,6 +1960,9 @@ bool virtqueue_poll(struct virtqueue *_vq, unsigned last_used_idx)
{
struct vring_virtqueue *vq = to_vvq(_vq);
if (unlikely(vq->broken))
return false;
virtio_mb(vq->weak_barriers);
return vq->packed_ring ? virtqueue_poll_packed(_vq, last_used_idx) :
virtqueue_poll_split(_vq, last_used_idx);