Revert "tuntap: add missing xdp flush"

This reverts commit 762c330d670e3d4b795cf7a8d761866fdd1eef49. The
reason is we try to batch packets for devmap which causes calling
xdp_do_flush() in the process context. Simply disabling preemption
may not work since process may move among processors which lead
xdp_do_flush() to miss some flushes on some processors.

So simply revert the patch, a follow-up patch will add the xdp flush
correctly.

Reported-by: Christoffer Dall <christoffer.dall@linaro.org>
Fixes: 762c330d670e ("tuntap: add missing xdp flush")
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index b52258c..2823a4a 100644 (file)
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -181,7 +181,6 @@ 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 {
@@ -1662,7 +1661,6 @@ 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;
@@ -1984,11 +1982,6 @@ 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;
 }
@@ -2325,13 +2318,6 @@ 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;
 }
@@ -3163,7 +3149,6 @@ 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;
 }