netdev - RE: [PATCH net-next v6 2/6] virtio_net: Remove command data from control

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Message-ID:
 <CH0PR12MB858041D6E8A46B12E4E795F9C9EC2@CH0PR12MB8580.namprd12.prod.outlook.com>
Date: Wed, 15 May 2024 13:27:43 +0000
From: Dan Jurgens <danielj@...dia.com>
To: Eric Dumazet <edumazet@...gle.com>
CC: "netdev@...r.kernel.org" <netdev@...r.kernel.org>, "mst@...hat.com"
	<mst@...hat.com>, "jasowang@...hat.com" <jasowang@...hat.com>,
	"xuanzhuo@...ux.alibaba.com" <xuanzhuo@...ux.alibaba.com>,
	"virtualization@...ts.linux.dev" <virtualization@...ts.linux.dev>,
	"davem@...emloft.net" <davem@...emloft.net>, "kuba@...nel.org"
	<kuba@...nel.org>, "pabeni@...hat.com" <pabeni@...hat.com>, Jiri Pirko
	<jiri@...dia.com>
Subject: RE: [PATCH net-next v6 2/6] virtio_net: Remove command data from
 control_buf

> From: Eric Dumazet <edumazet@...gle.com>
> Sent: Wednesday, May 15, 2024 7:45 AM
> To: Dan Jurgens <danielj@...dia.com>
> Cc: netdev@...r.kernel.org; mst@...hat.com; jasowang@...hat.com;
> xuanzhuo@...ux.alibaba.com; virtualization@...ts.linux.dev;
> davem@...emloft.net; kuba@...nel.org; pabeni@...hat.com; Jiri Pirko
> <jiri@...dia.com>
> Subject: Re: [PATCH net-next v6 2/6] virtio_net: Remove command data
> from control_buf
> 
> On Fri, May 3, 2024 at 10:25 PM Daniel Jurgens <danielj@...dia.com> wrote:
> >
> > Allocate memory for the data when it's used. Ideally the struct could
> > be on the stack, but we can't DMA stack memory. With this change only
> > the header and status memory are shared between commands, which will
> > allow using a tighter lock than RTNL.
> >
> > Signed-off-by: Daniel Jurgens <danielj@...dia.com>
> > Reviewed-by: Jiri Pirko <jiri@...dia.com>
> > ---
> >  drivers/net/virtio_net.c | 124
> > +++++++++++++++++++++++++++------------
> >  1 file changed, 85 insertions(+), 39 deletions(-)
> >
> > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index
> > 9cf93a8a4446..451879d570a8 100644
> > --- a/drivers/net/virtio_net.c
> > +++ b/drivers/net/virtio_net.c
> > @@ -368,15 +368,6 @@ struct virtio_net_ctrl_rss {  struct control_buf
> > {
> >         struct virtio_net_ctrl_hdr hdr;
> >         virtio_net_ctrl_ack status;
> > -       struct virtio_net_ctrl_mq mq;
> > -       u8 promisc;
> > -       u8 allmulti;
> > -       __virtio16 vid;
> > -       __virtio64 offloads;
> > -       struct virtio_net_ctrl_coal_tx coal_tx;
> > -       struct virtio_net_ctrl_coal_rx coal_rx;
> > -       struct virtio_net_ctrl_coal_vq coal_vq;
> > -       struct virtio_net_stats_capabilities stats_cap;
> >  };
> >
> >  struct virtnet_info {
> > @@ -2828,14 +2819,19 @@ static void virtnet_ack_link_announce(struct
> > virtnet_info *vi)
> >
> >  static int _virtnet_set_queues(struct virtnet_info *vi, u16
> > queue_pairs)  {
> > +       struct virtio_net_ctrl_mq *mq __free(kfree) = NULL;
> >         struct scatterlist sg;
> >         struct net_device *dev = vi->dev;
> >
> >         if (!vi->has_cvq || !virtio_has_feature(vi->vdev, VIRTIO_NET_F_MQ))
> >                 return 0;
> >
> > -       vi->ctrl->mq.virtqueue_pairs = cpu_to_virtio16(vi->vdev,
> queue_pairs);
> > -       sg_init_one(&sg, &vi->ctrl->mq, sizeof(vi->ctrl->mq));
> > +       mq = kzalloc(sizeof(*mq), GFP_KERNEL);
> > +       if (!mq)
> > +               return -ENOMEM;
> > +
> > +       mq->virtqueue_pairs = cpu_to_virtio16(vi->vdev, queue_pairs);
> > +       sg_init_one(&sg, mq, sizeof(*mq));
> >
> >         if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_MQ,
> >                                   VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET,
> > &sg)) { @@ -2864,6 +2860,7 @@ static int virtnet_set_queues(struct
> > virtnet_info *vi, u16 queue_pairs)
> >
> >  static int virtnet_close(struct net_device *dev)  {
> > +       u8 *promisc_allmulti  __free(kfree) = NULL;
> >         struct virtnet_info *vi = netdev_priv(dev);
> >         int i;
> >
> > @@ -2888,6 +2885,7 @@ static void virtnet_rx_mode_work(struct
> work_struct *work)
> >         struct scatterlist sg[2];
> >         struct virtio_net_ctrl_mac *mac_data;
> >         struct netdev_hw_addr *ha;
> > +       u8 *promisc_allmulti;
> >         int uc_count;
> >         int mc_count;
> >         void *buf;
> > @@ -2899,22 +2897,27 @@ static void virtnet_rx_mode_work(struct
> > work_struct *work)
> >
> >         rtnl_lock();
> >
> > -       vi->ctrl->promisc = ((dev->flags & IFF_PROMISC) != 0);
> > -       vi->ctrl->allmulti = ((dev->flags & IFF_ALLMULTI) != 0);
> > +       promisc_allmulti = kzalloc(sizeof(*promisc_allmulti), GFP_ATOMIC);
> > +       if (!promisc_allmulti) {
> 
> There is a missing rtnl_unlock() here ?

Yes, you're right. Will send a patch soon.
> 
> > +               dev_warn(&dev->dev, "Failed to set RX mode, no memory.\n");
> > +               return;
> > +       }
> >
> >