Re: [PATCH net v3] virtio_net: Fix error unwinding of XDP initialization
From: Feng Liu
Date: Wed May 10 2023 - 07:55:07 EST
On 2023-05-10 a.m.1:00, Jason Wang wrote:
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在 2023/5/9 09:43, Xuan Zhuo 写道:
On Mon, 8 May 2023 11:00:10 -0400, Feng Liu <feliu@xxxxxxxxxx> wrote:
On 2023-05-07 p.m.9:45, Xuan Zhuo wrote:
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On Sat, 6 May 2023 08:08:02 -0400, Feng Liu <feliu@xxxxxxxxxx> wrote:
On 2023-05-05 p.m.10:33, Xuan Zhuo wrote:
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On Tue, 2 May 2023 20:35:25 -0400, Feng Liu <feliu@xxxxxxxxxx> wrote:
When initializing XDP in virtnet_open(), some rq xdp initialization
may hit an error causing net device open failed. However, previous
rqs have already initialized XDP and enabled NAPI, which is not the
expected behavior. Need to roll back the previous rq initialization
to avoid leaks in error unwinding of init code.
Also extract a helper function of disable queue pairs, and use newly
introduced helper function in error unwinding and virtnet_close;
Issue: 3383038
Fixes: 754b8a21a96d ("virtio_net: setup xdp_rxq_info")
Signed-off-by: Feng Liu <feliu@xxxxxxxxxx>
Reviewed-by: William Tu <witu@xxxxxxxxxx>
Reviewed-by: Parav Pandit <parav@xxxxxxxxxx>
Reviewed-by: Simon Horman <simon.horman@xxxxxxxxxxxx>
Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Change-Id: Ib4c6a97cb7b837cfa484c593dd43a435c47ea68f
---
drivers/net/virtio_net.c | 30 ++++++++++++++++++++----------
1 file changed, 20 insertions(+), 10 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 8d8038538fc4..3737cf120cb7 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1868,6 +1868,13 @@ static int virtnet_poll(struct napi_struct
*napi, int budget)
return received;
}
+static void virtnet_disable_qp(struct virtnet_info *vi, int
qp_index)
+{
+ virtnet_napi_tx_disable(&vi->sq[qp_index].napi);
+ napi_disable(&vi->rq[qp_index].napi);
+ xdp_rxq_info_unreg(&vi->rq[qp_index].xdp_rxq);
+}
+
static int virtnet_open(struct net_device *dev)
{
struct virtnet_info *vi = netdev_priv(dev);
@@ -1883,20 +1890,26 @@ static int virtnet_open(struct net_device
*dev)
err = xdp_rxq_info_reg(&vi->rq[i].xdp_rxq, dev,
i, vi->rq[i].napi.napi_id);
if (err < 0)
- return err;
+ goto err_xdp_info_reg;
err =
xdp_rxq_info_reg_mem_model(&vi->rq[i].xdp_rxq,
MEM_TYPE_PAGE_SHARED, NULL);
- if (err < 0) {
- xdp_rxq_info_unreg(&vi->rq[i].xdp_rxq);
- return err;
- }
+ if (err < 0)
+ goto err_xdp_reg_mem_model;
virtnet_napi_enable(vi->rq[i].vq, &vi->rq[i].napi);
virtnet_napi_tx_enable(vi, vi->sq[i].vq,
&vi->sq[i].napi);
}
return 0;
+
+err_xdp_reg_mem_model:
+ xdp_rxq_info_unreg(&vi->rq[i].xdp_rxq);
+err_xdp_info_reg:
+ for (i = i - 1; i >= 0; i--)
+ virtnet_disable_qp(vi, i);
I would to know should we handle for these:
disable_delayed_refill(vi);
cancel_delayed_work_sync(&vi->refill);
Maybe we should call virtnet_close() with "i" directly.
Thanks.
Can’t use i directly here, because if xdp_rxq_info_reg fails, napi has
not been enabled for current qp yet, I should roll back from the queue
pairs where napi was enabled before(i--), otherwise it will hang at
napi
disable api
This is not the point, the key is whether we should handle with:
disable_delayed_refill(vi);
cancel_delayed_work_sync(&vi->refill);
Thanks.
OK, get the point. Thanks for your careful review. And I check the code
again.
There are two points that I need to explain:
1. All refill delay work calls(vi->refill, vi->refill_enabled) are based
on that the virtio interface is successfully opened, such as
virtnet_receive, virtnet_rx_resize, _virtnet_set_queues, etc. If there
is an error in the xdp reg here, it will not trigger these subsequent
functions. There is no need to call disable_delayed_refill() and
cancel_delayed_work_sync().
Maybe something is wrong. I think these lines may call delay work.
static int virtnet_open(struct net_device *dev)
{
struct virtnet_info *vi = netdev_priv(dev);
int i, err;
enable_delayed_refill(vi);
for (i = 0; i < vi->max_queue_pairs; i++) {
if (i < vi->curr_queue_pairs)
/* Make sure we have some buffers: if oom use
wq. */
--> if (!try_fill_recv(vi, &vi->rq[i], GFP_KERNEL))
--> schedule_delayed_work(&vi->refill, 0);
err = xdp_rxq_info_reg(&vi->rq[i].xdp_rxq, dev, i,
vi->rq[i].napi.napi_id);
if (err < 0)
return err;
err = xdp_rxq_info_reg_mem_model(&vi->rq[i].xdp_rxq,
MEM_TYPE_PAGE_SHARED,
NULL);
if (err < 0) {
xdp_rxq_info_unreg(&vi->rq[i].xdp_rxq);
return err;
}
virtnet_napi_enable(vi->rq[i].vq, &vi->rq[i].napi);
virtnet_napi_tx_enable(vi, vi->sq[i].vq, &vi->sq[i].napi);
}
return 0;
}
And I think, if we virtnet_open() return error, then the status of
virtnet
should like the status after virtnet_close().
Or someone has other opinion.
I agree, we need to disable and sync with the refill work.
Thanks
OK，got it.
Thanks Jason & Xuan
Thanks.
The logic here is different from that of
virtnet_close. virtnet_close is based on the success of virtnet_open and
the tx and rx has been carried out normally. For error unwinding, only
disable qp is needed. Also encapuslated a helper function of disable qp,
which is used ing error unwinding and virtnet close
2. The current error qp, which has not enabled NAPI, can only call xdp
unreg, and cannot call the interface of disable NAPI, otherwise the
kernel will be stuck. So for i-- the reason for calling disable qp on
the previous queue
Thanks
+
+ return err;
}
static int virtnet_poll_tx(struct napi_struct *napi, int budget)
@@ -2305,11 +2318,8 @@ static int virtnet_close(struct net_device
*dev)
/* Make sure refill_work doesn't re-enable napi! */
cancel_delayed_work_sync(&vi->refill);
- for (i = 0; i < vi->max_queue_pairs; i++) {
- virtnet_napi_tx_disable(&vi->sq[i].napi);
- napi_disable(&vi->rq[i].napi);
- xdp_rxq_info_unreg(&vi->rq[i].xdp_rxq);
- }
+ for (i = 0; i < vi->max_queue_pairs; i++)
+ virtnet_disable_qp(vi, i);
return 0;
}
--
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