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tuntap: add missing xdp flush

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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: 761876c857 ("tap: XDP support")
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jason Wang 2018-02-07 17:14:46 +08:00 committed by David S. Miller
parent cb9f7a9a5c
commit 762c330d67
1 changed files with 15 additions and 0 deletions
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15
drivers/net/tun.c
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@ -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;
}