linux-kernel - Re: [PATCH net-next v7 4/9] net: devmem: Implement TX path

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Message-ID: <CAHS8izNfyfVhMj0wBvP0qa=7E4xL+eo9wn_Fi4o2PT8piwACWA@mail.gmail.com>
Date: Fri, 21 Mar 2025 15:15:14 -0700
From: Mina Almasry <almasrymina@...gle.com>
To: Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-doc@...r.kernel.org, kvm@...r.kernel.org, 
	virtualization@...ts.linux.dev, linux-kselftest@...r.kernel.org, 
	Kuniyuki Iwashima <kuniyu@...zon.com>, Donald Hunter <donald.hunter@...il.com>, 
	Jakub Kicinski <kuba@...nel.org>, "David S. Miller" <davem@...emloft.net>, 
	Eric Dumazet <edumazet@...gle.com>, Simon Horman <horms@...nel.org>, Jonathan Corbet <corbet@....net>, 
	Andrew Lunn <andrew+netdev@...n.ch>, Jeroen de Borst <jeroendb@...gle.com>, 
	Harshitha Ramamurthy <hramamurthy@...gle.com>, Willem de Bruijn <willemb@...gle.com>, 
	David Ahern <dsahern@...nel.org>, Neal Cardwell <ncardwell@...gle.com>, 
	Stefan Hajnoczi <stefanha@...hat.com>, Stefano Garzarella <sgarzare@...hat.com>, 
	"Michael S. Tsirkin" <mst@...hat.com>, Jason Wang <jasowang@...hat.com>, 
	Xuan Zhuo <xuanzhuo@...ux.alibaba.com>, Eugenio Pérez <eperezma@...hat.com>, 
	Shuah Khan <shuah@...nel.org>, sdf@...ichev.me, asml.silence@...il.com, dw@...idwei.uk, 
	Jamal Hadi Salim <jhs@...atatu.com>, Victor Nogueira <victor@...atatu.com>, 
	Pedro Tammela <pctammela@...atatu.com>, Samiullah Khawaja <skhawaja@...gle.com>, 
	Kaiyuan Zhang <kaiyuanz@...gle.com>
Subject: Re: [PATCH net-next v7 4/9] net: devmem: Implement TX path

On Tue, Mar 18, 2025 at 1:53 AM Paolo Abeni <pabeni@...hat.com> wrote:
>
> Adding Kuniyuki.
>
> On 3/8/25 10:40 PM, Mina Almasry wrote:
> > @@ -931,10 +932,67 @@ int netdev_nl_bind_rx_doit(struct sk_buff *skb, struct genl_info *info)
> >       return err;
> >  }
> >
> > -/* stub */
> >  int netdev_nl_bind_tx_doit(struct sk_buff *skb, struct genl_info *info)
> >  {
> > -     return 0;
> > +     struct net_devmem_dmabuf_binding *binding;
> > +     struct list_head *sock_binding_list;
> > +     struct net_device *netdev;
> > +     u32 ifindex, dmabuf_fd;
> > +     struct sk_buff *rsp;
> > +     int err = 0;
> > +     void *hdr;
> > +
> > +     if (GENL_REQ_ATTR_CHECK(info, NETDEV_A_DEV_IFINDEX) ||
> > +         GENL_REQ_ATTR_CHECK(info, NETDEV_A_DMABUF_FD))
> > +             return -EINVAL;
> > +
> > +     ifindex = nla_get_u32(info->attrs[NETDEV_A_DEV_IFINDEX]);
> > +     dmabuf_fd = nla_get_u32(info->attrs[NETDEV_A_DMABUF_FD]);
> > +
> > +     sock_binding_list = genl_sk_priv_get(&netdev_nl_family,
> > +                                          NETLINK_CB(skb).sk);
> > +     if (IS_ERR(sock_binding_list))
> > +             return PTR_ERR(sock_binding_list);
> > +
> > +     rsp = genlmsg_new(GENLMSG_DEFAULT_SIZE, GFP_KERNEL);
> > +     if (!rsp)
> > +             return -ENOMEM;
> > +
> > +     hdr = genlmsg_iput(rsp, info);
> > +     if (!hdr) {
> > +             err = -EMSGSIZE;
> > +             goto err_genlmsg_free;
> > +     }
> > +
> > +     rtnl_lock();
>
> The above could possibly be a rtnl_net_lock(), right?
>
> (not strictily related to this series) The same for the existing
> rtnl_lock() call in netdev-genl.c, right?
>

Actually I think this can follow the example set in commit
1d22d3060b9b ("net: drop rtnl_lock for queue_mgmt operations") and
take the netdev_get_by_index_lock().


-- 
Thanks,
Mina