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Subject[PATCH V4 net 1/3] Revert "tuntap: add missing xdp flush"
Date
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>
---
drivers/net/tun.c | 15 ---------------
1 file changed, 15 deletions(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index b52258c..2823a4a 100644
--- 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;
}
--
2.7.4
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