ice, xsk: Move Rx allocation out of while-loop

Instead doing the check for allocation in each loop, move it outside
the while loop and do it every NAPI loop.

This change boosts the xdpsock rxdrop scenario with 15% more
packets-per-second.

Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Link: https://lore.kernel.org/r/20201211085410.59350-1-bjorn.topel@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/intel/ice/ice_xsk.c

@@ -570,12 +570,6 @@ int ice_clean_rx_irq_zc(struct ice_ring *rx_ring, int budget)
 		u16 vlan_tag = 0;
 		u8 rx_ptype;
 
-		if (cleaned_count >= ICE_RX_BUF_WRITE) {
-			failure |= ice_alloc_rx_bufs_zc(rx_ring,
-							cleaned_count);
-			cleaned_count = 0;
-		}
-
 		rx_desc = ICE_RX_DESC(rx_ring, rx_ring->next_to_clean);
 
 		stat_err_bits = BIT(ICE_RX_FLEX_DESC_STATUS0_DD_S);
@@ -642,6 +636,9 @@ int ice_clean_rx_irq_zc(struct ice_ring *rx_ring, int budget)
 		ice_receive_skb(rx_ring, skb, vlan_tag);
 	}
 
+	if (cleaned_count >= ICE_RX_BUF_WRITE)
+		failure = !ice_alloc_rx_bufs_zc(rx_ring, cleaned_count);
+
 	ice_finalize_xdp_rx(rx_ring, xdp_xmit);
 	ice_update_rx_ring_stats(rx_ring, total_rx_packets, total_rx_bytes);