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 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: tuntap-correctly-add-the-missing-xdp-flush.patch and it can be found in the queue-4.14 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 19:02:12 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 @@ -1333,6 +1333,7 @@ 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-4.14/tuntap-correctly-add-the-missing-xdp-flush.patch queue-4.14/virtio-net-disable-napi-only-when-enabled-during-xdp-set.patch queue-4.14/tuntap-disable-preemption-during-xdp-processing.patch