4.19-stable review patch. If anyone has any objections, please let me know.
------------------
From: Matthew Cover werekraken@gmail.com
[ Upstream commit 8ebebcba559a1bfbaec7bbda64feb9870b9c58da ]
When writing packets to a descriptor associated with a combined queue, the packets should end up on that queue.
Before this change all packets written to any descriptor associated with a tap interface end up on rx-0, even when the descriptor is associated with a different queue.
The rx traffic can be generated by either of the following. 1. a simple tap program which spins up multiple queues and writes packets to each of the file descriptors 2. tx from a qemu vm with a tap multiqueue netdev
The queue for rx traffic can be observed by either of the following (done on the hypervisor in the qemu case). 1. a simple netmap program which opens and reads from per-queue descriptors 2. configuring RPS and doing per-cpu captures with rxtxcpu
Alternatively, if you printk() the return value of skb_get_rx_queue() just before each instance of netif_receive_skb() in tun.c, you will get 65535 for every skb.
Calling skb_record_rx_queue() to set the rx queue to the queue_index fixes the association between descriptor and rx queue.
Signed-off-by: Matthew Cover matthew.cover@stackpath.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/tun.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
--- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -1527,6 +1527,7 @@ static void tun_rx_batched(struct tun_st
if (!rx_batched || (!more && skb_queue_empty(queue))) { local_bh_disable(); + skb_record_rx_queue(skb, tfile->queue_index); netif_receive_skb(skb); local_bh_enable(); return; @@ -1546,8 +1547,11 @@ static void tun_rx_batched(struct tun_st struct sk_buff *nskb;
local_bh_disable(); - while ((nskb = __skb_dequeue(&process_queue))) + while ((nskb = __skb_dequeue(&process_queue))) { + skb_record_rx_queue(nskb, tfile->queue_index); netif_receive_skb(nskb); + } + skb_record_rx_queue(skb, tfile->queue_index); netif_receive_skb(skb); local_bh_enable(); }