From: Mao Wenan <wenan.mao@linux.alibaba.com> To: mst@redhat.com, jasowang@redhat.com Cc: virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org, Mao Wenan <wenan.mao@linux.alibaba.com> Subject: [PATCH -next v2] virtio_net: Avoid loop in virtnet_poll Date: Sun, 2 Aug 2020 13:56:33 +0800 [thread overview] Message-ID: <1596347793-55894-1-git-send-email-wenan.mao@linux.alibaba.com> (raw) In-Reply-To: <20200802003818-mutt-send-email-mst@kernel.org> 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> --- v1->v2: fix it in virtqueue_poll suggested by Michael S. Tsirkin <mst@redhat.com> drivers/virtio/virtio_ring.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index 58b96ba..4f7c73e 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); -- 1.8.3.1
WARNING: multiple messages have this Message-ID (diff)
From: Mao Wenan <wenan.mao@linux.alibaba.com> To: mst@redhat.com, jasowang@redhat.com Cc: virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org, Mao Wenan <wenan.mao@linux.alibaba.com> Subject: [PATCH -next v2] virtio_net: Avoid loop in virtnet_poll Date: Sun, 02 Aug 2020 05:56:33 +0000 [thread overview] Message-ID: <1596347793-55894-1-git-send-email-wenan.mao@linux.alibaba.com> (raw) In-Reply-To: <20200802003818-mutt-send-email-mst@kernel.org> 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> --- v1->v2: fix it in virtqueue_poll suggested by Michael S. Tsirkin <mst@redhat.com> drivers/virtio/virtio_ring.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index 58b96ba..4f7c73e 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); -- 1.8.3.1
next prev parent reply other threads:[~2020-08-02 5:57 UTC|newest] Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-08-02 3:41 [PATCH -next] virtio_net: Avoid loop in virtnet_poll Mao Wenan 2020-08-02 4:40 ` Michael S. Tsirkin 2020-08-02 5:56 ` Mao Wenan [this message] 2020-08-02 5:56 ` [PATCH -next v2] " Mao Wenan 2020-08-02 6:25 ` Michael S. Tsirkin 2020-08-02 6:25 ` Michael S. Tsirkin 2020-08-02 6:25 ` Michael S. Tsirkin 2020-08-02 6:26 ` Michael S. Tsirkin 2020-08-02 6:26 ` Michael S. Tsirkin 2020-08-02 6:26 ` Michael S. Tsirkin 2020-08-02 7:31 ` maowenan 2020-08-02 7:31 ` maowenan 2020-08-02 7:44 ` [PATCH -next v3] virtio_ring: Avoid loop when vq is broken in virtqueue_poll Mao Wenan 2020-08-02 7:44 ` Mao Wenan 2020-08-04 2:42 ` Jason Wang 2020-08-04 2:42 ` Jason Wang 2020-08-04 2:42 ` Jason Wang
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