On Thu, 23 Jan 2020 17:14:06 +0000, Haiyang Zhang wrote:

quoted

quoted

Changes:
	v3: Minor code and comment updates.
        v2: Added XDP_TX support. Addressed review comments.  

How does the locking of the TX path work? You seem to be just calling the
normal xmit method, but you don't hold the xmit queue lock, so the stack can
start xmit concurrently, no?  

The netvsc and vmbus can handle concurrent transmits, except the msd 
(Multi-Send Data) field which can only be used by one queue. 

I already added a new flag to netvsc_send(), so packets from XDP_TX won't use 
the msd.

I see, there's a few non-atomic counters there, but maybe that's not a
big deal.

What frees the skb if the ring is full, and netvsc_send_pkt() returns
-EAGAIN? Nothing checks the return value from netvsc_xdp_xmit().