igc: Replace IGC_TX_FLAGS_XDP flag by an enum

Up to this point, Tx buffers are associated with either a skb or a xdpf,
and the IGC_TX_FLAGS_XDP flag was enough to distinguish between these
two case. However, with upcoming patches that will add AF_XDP zero-copy
support, a third case will be introduced so this flag-based approach
won't fit well.

In preparation to land AF_XDP zero-copy support, replace the
IGC_TX_FLAGS_XDP flag by an enum which will be extended once zero-copy
support is introduced to the driver.

Signed-off-by: Andre Guedes <andre.guedes@intel.com>
Signed-off-by: Vedang Patel <vedang.patel@intel.com>
Signed-off-by: Jithu Joseph <jithu.joseph@intel.com>
Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Tested-by: Dvora Fuxbrumer <dvorax.fuxbrumer@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/igc/igc.h

@@ -390,8 +390,6 @@ enum igc_tx_flags {
 	/* olinfo flags */
 	IGC_TX_FLAGS_IPV4	= 0x10,
 	IGC_TX_FLAGS_CSUM	= 0x20,
-
-	IGC_TX_FLAGS_XDP	= 0x100,
 };
 
 enum igc_boards {
@@ -408,12 +406,18 @@ enum igc_boards {
 #define TXD_USE_COUNT(S)	DIV_ROUND_UP((S), IGC_MAX_DATA_PER_TXD)
 #define DESC_NEEDED	(MAX_SKB_FRAGS + 4)
 
+enum igc_tx_buffer_type {
+	IGC_TX_BUFFER_TYPE_SKB,
+	IGC_TX_BUFFER_TYPE_XDP,
+};
+
 /* wrapper around a pointer to a socket buffer,
  * so a DMA handle can be stored along with the buffer
  */
 struct igc_tx_buffer {
 	union igc_adv_tx_desc *next_to_watch;
 	unsigned long time_stamp;
+	enum igc_tx_buffer_type type;
 	union {
 		struct sk_buff *skb;
 		struct xdp_frame *xdpf;

drivers/net/ethernet/intel/igc/igc_main.c

@@ -191,10 +191,17 @@ static void igc_clean_tx_ring(struct igc_ring *tx_ring)
 	while (i != tx_ring->next_to_use) {
 		union igc_adv_tx_desc *eop_desc, *tx_desc;
 
-		if (tx_buffer->tx_flags & IGC_TX_FLAGS_XDP)
+		switch (tx_buffer->type) {
+		case IGC_TX_BUFFER_TYPE_XDP:
 			xdp_return_frame(tx_buffer->xdpf);
-		else
+			break;
+		case IGC_TX_BUFFER_TYPE_SKB:
 			dev_kfree_skb_any(tx_buffer->skb);
+			break;
+		default:
+			netdev_warn_once(tx_ring->netdev, "Unknown Tx buffer type\n");
+			break;
+		}
 
 		igc_unmap_tx_buffer(tx_ring->dev, tx_buffer);
 
@@ -1360,6 +1367,7 @@ static netdev_tx_t igc_xmit_frame_ring(struct sk_buff *skb,
 
 	/* record the location of the first descriptor for this packet */
 	first = &tx_ring->tx_buffer_info[tx_ring->next_to_use];
+	first->type = IGC_TX_BUFFER_TYPE_SKB;
 	first->skb = skb;
 	first->bytecount = skb->len;
 	first->gso_segs = 1;
@@ -1943,8 +1951,8 @@ static int igc_xdp_init_tx_buffer(struct igc_tx_buffer *buffer,
 		return -ENOMEM;
 	}
 
+	buffer->type = IGC_TX_BUFFER_TYPE_XDP;
 	buffer->xdpf = xdpf;
-	buffer->tx_flags = IGC_TX_FLAGS_XDP;
 	buffer->protocol = 0;
 	buffer->bytecount = xdpf->len;
 	buffer->gso_segs = 1;
@@ -2305,10 +2313,17 @@ static bool igc_clean_tx_irq(struct igc_q_vector *q_vector, int napi_budget)
 		total_bytes += tx_buffer->bytecount;
 		total_packets += tx_buffer->gso_segs;
 
-		if (tx_buffer->tx_flags & IGC_TX_FLAGS_XDP)
+		switch (tx_buffer->type) {
+		case IGC_TX_BUFFER_TYPE_XDP:
 			xdp_return_frame(tx_buffer->xdpf);
-		else
+			break;
+		case IGC_TX_BUFFER_TYPE_SKB:
 			napi_consume_skb(tx_buffer->skb, napi_budget);
+			break;
+		default:
+			netdev_warn_once(tx_ring->netdev, "Unknown Tx buffer type\n");
+			break;
+		}
 
 		igc_unmap_tx_buffer(tx_ring->dev, tx_buffer);