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| author | Mao Wenan <wenan.mao@linux.alibaba.com> | 2020-08-02 15:44:09 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-08-26 10:40:57 +0200 |
| commit | 05724341d9db1f662e30620902cd6d6018e17609 (patch) | |
| tree | 070991d0e5fa7b0617008f236c391331529b3c05 | |
| parent | 34f8368f66342c73a3b2d45ffb701524600cba9b (diff) | |
| download | linux-stable-05724341d9db1f662e30620902cd6d6018e17609.tar.gz linux-stable-05724341d9db1f662e30620902cd6d6018e17609.tar.bz2 linux-stable-05724341d9db1f662e30620902cd6d6018e17609.zip | |
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.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index 58b96baa8d48..4f7c73e6052f 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -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); |