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Commit 762c330d authored by Jason Wang's avatar Jason Wang Committed by David S. Miller
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tuntap: add missing xdp flush 



When using devmap to redirect packets between interfaces,
xdp_do_flush() is usually a must to flush any batched
packets. Unfortunately this is missed in current tuntap
implementation.

Unlike most hardware driver which did XDP inside NAPI loop and call
xdp_do_flush() at then end of each round of poll. TAP did it in the
context of process e.g tun_get_user(). So fix this by count the
pending redirected packets and flush when it exceeds NAPI_POLL_WEIGHT
or MSG_MORE was cleared by sendmsg() caller.

With this fix, xdp_redirect_map works again between two TAPs.

Fixes: 761876c8 ("tap: XDP support")
Signed-off-by: default avatarJason Wang <jasowang@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent cb9f7a9a

drivers/net/tun.c

+15 −0
Original line number Diff line number Diff line
@@ -181,6 +181,7 @@ struct tun_file { 
	struct tun_struct *detached;

	struct ptr_ring tx_ring;

	struct xdp_rxq_info xdp_rxq;

	int xdp_pending_pkts;

};



struct tun_flow_entry {
@@ -1665,6 +1666,7 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun, 
		case XDP_REDIRECT:

			get_page(alloc_frag->page);

			alloc_frag->offset += buflen;

			++tfile->xdp_pending_pkts;

			err = xdp_do_redirect(tun->dev, &xdp, xdp_prog);

			if (err)

				goto err_redirect;
@@ -1986,6 +1988,11 @@ static ssize_t tun_chr_write_iter(struct kiocb *iocb, struct iov_iter *from) 
	result = tun_get_user(tun, tfile, NULL, from,

			      file->f_flags & O_NONBLOCK, false);



	if (tfile->xdp_pending_pkts) {

		tfile->xdp_pending_pkts = 0;

		xdp_do_flush_map();

	}



	tun_put(tun);

	return result;

}
@@ -2322,6 +2329,13 @@ static int tun_sendmsg(struct socket *sock, struct msghdr *m, size_t total_len) 
	ret = tun_get_user(tun, tfile, m->msg_control, &m->msg_iter,

			   m->msg_flags & MSG_DONTWAIT,

			   m->msg_flags & MSG_MORE);



	if (tfile->xdp_pending_pkts >= NAPI_POLL_WEIGHT ||

	    !(m->msg_flags & MSG_MORE)) {

		tfile->xdp_pending_pkts = 0;

		xdp_do_flush_map();

	}



	tun_put(tun);

	return ret;

}
@@ -3153,6 +3167,7 @@ static int tun_chr_open(struct inode *inode, struct file * file) 
	sock_set_flag(&tfile->sk, SOCK_ZEROCOPY);



	memset(&tfile->tx_ring, 0, sizeof(tfile->tx_ring));

	tfile->xdp_pending_pkts = 0;



	return 0;

}