Re: [PATCH V4 net 3/3] tuntap: correctly add the missing XDP flush

[David Miller]

From: Jason Wang 
Date: Sat, 24 Feb 2018 11:32:26 +0800

> 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 
> Fixes: 761876c857cb ("tap: XDP support")
> Signed-off-by: Jason Wang 

Applied, and all 3 patches queued up for -stable.

Thanks.

[PATCH V4 net 3/3] tuntap: correctly add the missing XDP flush

[Jason Wang]

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 
Fixes: 761876c857cb ("tap: XDP support")
Signed-off-by: Jason Wang 
---
 drivers/net/tun.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 63d39fe6..7433bb2 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1663,6 +1663,7 @@ static struct sk_buff *tun_build_skb(struct tun_struct 
*tun,
get_page(alloc_frag->page);
alloc_frag->offset += buflen;
err = xdp_do_redirect(tun->dev, , xdp_prog);
+   xdp_do_flush_map();
if (err)
goto err_redirect;
rcu_read_unlock();
-- 
2.7.4