net: xsk: don't return frames via the allocator on error

xdp_return_buff() is used when frame has been successfully
handled (transmitted) or if an error occurred during delayed
processing and there is no way to report it back to
xdp_do_redirect().

In case of __xsk_rcv_zc() error is propagated all the way
back to the driver, so there is no need to call
xdp_return_buff().  Driver will recycle the frame anyway
after seeing that error happened.

Fixes: 173d3ad ("xsk: add zero-copy support for Rx")
Signed-off-by: Jakub Kicinski <[email protected]>
Acked-by: Björn Töpel <[email protected]>
Signed-off-by: Daniel Borkmann <[email protected]>

Author: Jakub Kicinski

net/xdp/xsk.c

@@ -84,10 +84,8 @@ static int __xsk_rcv_zc(struct xdp_sock *xs, struct xdp_buff *xdp, u32 len)
 {
 	int err = xskq_produce_batch_desc(xs->rx, (u64)xdp->handle, len);
 
-	if (err) {
-		xdp_return_buff(xdp);
+	if (err)
 		xs->rx_dropped++;
-	}
 
 	return err;
 }