i40e: simplify Rx buffer recycle

Currently, the dma, addr and handle are modified when we reuse Rx buffers
in zero-copy mode. However, this is not required as the inputs to the
function are copies, not the original values themselves. As we use the
copies within the function, we can use the original 'old_bi' values
directly without having to mask and add the headroom.
Signed-off-by: Kevin Laatz <kevin.laatz@intel.com>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

drivers/net/ethernet/intel/i40e/i40e_xsk.c

@@ -420,8 +420,6 @@ static void i40e_reuse_rx_buffer_zc(struct i40e_ring *rx_ring,
 				    struct i40e_rx_buffer *old_bi)
 {
 	struct i40e_rx_buffer *new_bi = &rx_ring->rx_bi[rx_ring->next_to_alloc];
-	unsigned long mask = (unsigned long)rx_ring->xsk_umem->chunk_mask;
-	u64 hr = rx_ring->xsk_umem->headroom + XDP_PACKET_HEADROOM;
 	u16 nta = rx_ring->next_to_alloc;
 
 	/* update, and store next to alloc */
@@ -429,14 +427,9 @@ static void i40e_reuse_rx_buffer_zc(struct i40e_ring *rx_ring,
 	rx_ring->next_to_alloc = (nta < rx_ring->count) ? nta : 0;
 
 	/* transfer page from old buffer to new buffer */
-	new_bi->dma = old_bi->dma & mask;
-	new_bi->dma += hr;
-
-	new_bi->addr = (void *)((unsigned long)old_bi->addr & mask);
-	new_bi->addr += hr;
-
-	new_bi->handle = old_bi->handle & mask;
-	new_bi->handle += rx_ring->xsk_umem->headroom;
+	new_bi->dma = old_bi->dma;
+	new_bi->addr = old_bi->addr;
+	new_bi->handle = old_bi->handle;
 
 	old_bi->addr = NULL;
 }