igb: Fix passing 0 to ERR_PTR in igb_run_xdp()

igb_run_xdp() converts customed xdp action to a negative error code
with the sk_buff pointer type which be checked with IS_ERR in
igb_clean_rx_irq(). Remove this error pointer handing instead use plain
int return value.

Reviewed-by: Maciej Fijalkowski <[email protected]>
Reviewed-by: Jacob Keller <[email protected]>
Signed-off-by: Yue Haibing <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Tested-by: Chandan Kumar Rout <[email protected]> (A Contingent Worker at Intel)
Signed-off-by: Tony Nguyen <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: Yue Haibing

drivers/net/ethernet/intel/igb/igb_main.c

@@ -8658,9 +8658,8 @@ static struct sk_buff *igb_build_skb(struct igb_ring *rx_ring,
 	return skb;
 }
 
-static struct sk_buff *igb_run_xdp(struct igb_adapter *adapter,
-				   struct igb_ring *rx_ring,
-				   struct xdp_buff *xdp)
+static int igb_run_xdp(struct igb_adapter *adapter, struct igb_ring *rx_ring,
+		       struct xdp_buff *xdp)
 {
 	int err, result = IGB_XDP_PASS;
 	struct bpf_prog *xdp_prog;
@@ -8700,7 +8699,7 @@ static struct sk_buff *igb_run_xdp(struct igb_adapter *adapter,
 		break;
 	}
 xdp_out:
-	return ERR_PTR(-result);
+	return result;
 }
 
 static unsigned int igb_rx_frame_truesize(struct igb_ring *rx_ring,
@@ -8826,10 +8825,6 @@ static bool igb_cleanup_headers(struct igb_ring *rx_ring,
 				union e1000_adv_rx_desc *rx_desc,
 				struct sk_buff *skb)
 {
-	/* XDP packets use error pointer so abort at this point */
-	if (IS_ERR(skb))
-		return true;
-
 	if (unlikely((igb_test_staterr(rx_desc,
 				       E1000_RXDEXT_ERR_FRAME_ERR_MASK)))) {
 		struct net_device *netdev = rx_ring->netdev;
@@ -8983,6 +8978,7 @@ static int igb_clean_rx_irq(struct igb_q_vector *q_vector, const int budget)
 	struct xdp_buff xdp;
 	u32 frame_sz = 0;
 	int rx_buf_pgcnt;
+	int xdp_res = 0;
 
 	/* Frame size depend on rx_ring setup when PAGE_SIZE=4K */
 #if (PAGE_SIZE < 8192)
@@ -9040,12 +9036,10 @@ static int igb_clean_rx_irq(struct igb_q_vector *q_vector, const int budget)
 			/* At larger PAGE_SIZE, frame_sz depend on len size */
 			xdp.frame_sz = igb_rx_frame_truesize(rx_ring, size);
 #endif
-			skb = igb_run_xdp(adapter, rx_ring, &xdp);
+			xdp_res = igb_run_xdp(adapter, rx_ring, &xdp);
 		}
 
-		if (IS_ERR(skb)) {
-			unsigned int xdp_res = -PTR_ERR(skb);
-
+		if (xdp_res) {
 			if (xdp_res & (IGB_XDP_TX | IGB_XDP_REDIR)) {
 				xdp_xmit |= xdp_res;
 				igb_rx_buffer_flip(rx_ring, rx_buffer, size);
@@ -9064,7 +9058,7 @@ static int igb_clean_rx_irq(struct igb_q_vector *q_vector, const int budget)
 						&xdp, timestamp);
 
 		/* exit if we failed to retrieve a buffer */
-		if (!skb) {
+		if (!xdp_res && !skb) {
 			rx_ring->rx_stats.alloc_failed++;
 			rx_buffer->pagecnt_bias++;
 			break;
@@ -9078,7 +9072,7 @@ static int igb_clean_rx_irq(struct igb_q_vector *q_vector, const int budget)
 			continue;
 
 		/* verify the packet layout is correct */
-		if (igb_cleanup_headers(rx_ring, rx_desc, skb)) {
+		if (xdp_res || igb_cleanup_headers(rx_ring, rx_desc, skb)) {
 			skb = NULL;
 			continue;
 		}