Patch "tuntap: correctly add the missing XDP flush" has been added to the 4.15-stable tree

Patch "tuntap: correctly add the missing XDP flush" has been added to the 4.15-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    tuntap: correctly add the missing XDP flush

to the 4.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     tuntap-correctly-add-the-missing-xdp-flush.patch
and it can be found in the queue-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Tue Mar  6 19:02:56 PST 2018
From: Jason Wang <jasowang@redhat.com>
Date: Sat, 24 Feb 2018 11:32:26 +0800
Subject: tuntap: correctly add the missing XDP flush

From: Jason Wang <jasowang@redhat.com>


[ Upstream commit 1bb4f2e868a2891ab8bc668b8173d6ccb8c4ce6f ]

We don't flush batched XDP packets through xdp_do_flush_map(), this
will cause packets stall at TX queue. Consider we don't do XDP on NAPI
poll(), the only possible fix is to call xdp_do_flush_map()
immediately after xdp_do_redirect().

Note, this in fact won't try to batch packets through devmap, we could
address in the future.

Reported-by: Christoffer Dall <christoffer.dall@linaro.org>
Fixes: 761876c857cb ("tap: XDP support")
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/tun.c |    1 +
 1 file changed, 1 insertion(+)

--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1490,6 +1490,7 @@ static struct sk_buff *tun_build_skb(str
 			get_page(alloc_frag->page);
 			alloc_frag->offset += buflen;
 			err = xdp_do_redirect(tun->dev, &xdp, xdp_prog);
+			xdp_do_flush_map();
 			if (err)
 				goto err_redirect;
 			rcu_read_unlock();


Patches currently in stable-queue which might be from jasowang@redhat.com are

queue-4.15/tuntap-correctly-add-the-missing-xdp-flush.patch
queue-4.15/virtio-net-disable-napi-only-when-enabled-during-xdp-set.patch
queue-4.15/tuntap-disable-preemption-during-xdp-processing.patch