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authorMao Wenan <wenan.mao@linux.alibaba.com>2020-08-02 15:44:09 +0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2020-08-26 10:31:01 +0200
commit9f489d30979bd352ffbd555020b6ca79efb93b89 (patch)
tree9d1193958e5d3580ade9b5d6144c8f42e6141ab9
parent4f419fd2f86d7db1d7fcb6f2fb9fde2c9fdd8bbe (diff)
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virtio_ring: Avoid loop when vq is broken in virtqueue_poll
[ Upstream commit 481a0d7422db26fb63e2d64f0652667a5c6d0f3e ] 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> Signed-off-by: Sasha Levin <sashal@kernel.org>
-rw-r--r--drivers/virtio/virtio_ring.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 6228b48d1e12..df7980aef927 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -828,6 +828,9 @@ 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 (u16)last_used_idx != virtio16_to_cpu(_vq->vdev, vq->vring.used->idx);
}