[bpf-next V2 PATCH 10/14] tun: setup xdp_rxq_info

[Jesper Dangaard Brouer]

Driver hook points for xdp_rxq_info:
 * reg  : tun_attach
 * unreg: __tun_detach

I've done some manual testing of this tun driver, but I would
appriciate good review and someone else running their use-case tests,
as I'm not 100% sure I understand the tfile->detached semantics.

V2: Removed the skb_array_cleanup() call from V1 by request from Jason Wang.

Cc: Jason Wang <jasow...@redhat.com>
Cc: "Michael S. Tsirkin" <m...@redhat.com>
Cc: Willem de Bruijn <will...@google.com>
Signed-off-by: Jesper Dangaard Brouer <bro...@redhat.com>
---
 drivers/net/tun.c |   24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index e367d6310353..e7c5f4b2a9a6 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -180,6 +180,7 @@ struct tun_file {
        struct list_head next;
        struct tun_struct *detached;
        struct skb_array tx_array;
+       struct xdp_rxq_info xdp_rxq;
 };
 
 struct tun_flow_entry {
@@ -687,8 +688,10 @@ static void __tun_detach(struct tun_file *tfile, bool 
clean)
                            tun->dev->reg_state == NETREG_REGISTERED)
                                unregister_netdevice(tun->dev);
                }
-               if (tun)
+               if (tun) {
                        skb_array_cleanup(&tfile->tx_array);
+                       xdp_rxq_info_unreg(&tfile->xdp_rxq);
+               }
                sock_put(&tfile->sk);
        }
 }
@@ -728,11 +731,13 @@ static void tun_detach_all(struct net_device *dev)
                tun_napi_del(tun, tfile);
                /* Drop read queue */
                tun_queue_purge(tfile);
+               xdp_rxq_info_unreg(&tfile->xdp_rxq);
                sock_put(&tfile->sk);
        }
        list_for_each_entry_safe(tfile, tmp, &tun->disabled, next) {
                tun_enable_queue(tfile);
                tun_queue_purge(tfile);
+               xdp_rxq_info_unreg(&tfile->xdp_rxq);
                sock_put(&tfile->sk);
        }
        BUG_ON(tun->numdisabled != 0);
@@ -784,6 +789,22 @@ static int tun_attach(struct tun_struct *tun, struct file 
*file,
 
        tfile->queue_index = tun->numqueues;
        tfile->socket.sk->sk_shutdown &= ~RCV_SHUTDOWN;
+
+       if (tfile->detached) {
+               /* Re-attach detached tfile, updating XDP queue_index */
+               WARN_ON(!xdp_rxq_info_is_reg(&tfile->xdp_rxq));
+
+               if (tfile->xdp_rxq.queue_index    != tfile->queue_index)
+                       tfile->xdp_rxq.queue_index = tfile->queue_index;
+       } else {
+               /* Setup XDP RX-queue info, for new tfile getting attached */
+               err = xdp_rxq_info_reg(&tfile->xdp_rxq,
+                                      tun->dev, tfile->queue_index);
+               if (err < 0)
+                       goto out;
+               err = 0;
+       }
+
        rcu_assign_pointer(tfile->tun, tun);
        rcu_assign_pointer(tun->tfiles[tun->numqueues], tfile);
        tun->numqueues++;
@@ -1508,6 +1529,7 @@ static struct sk_buff *tun_build_skb(struct tun_struct 
*tun,
                xdp.data = buf + pad;
                xdp_set_data_meta_invalid(&xdp);
                xdp.data_end = xdp.data + len;
+               xdp.rxq = &tfile->xdp_rxq;
                orig_data = xdp.data;
                act = bpf_prog_run_xdp(xdp_prog, &xdp);