bnx2x: Filter packets on FCoE rings

Whenever bnx2x fails to transmit a packet due to a full Tx ring, if the
ring size is zero (indicating an FCoE ring) driver filters the packet out
and gracefully continues.
Driver also gathers statistics on such filtered packets.

Signed-off-by: Dmitry Kravkov <dmitry@broadcom.com>
Signed-off-by: Yuval Mintz <yuvalmin@broadcom.com>
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c

@@ -3127,11 +3127,16 @@ netdev_tx_t bnx2x_start_xmit(struct sk_buff *skb, struct net_device *dev)
 			BDS_PER_TX_PKT +
 			NEXT_CNT_PER_TX_PKT(MAX_BDS_PER_TX_PKT))) {
 		/* Handle special storage cases separately */
-		if (txdata->tx_ring_size != 0) {
-			BNX2X_ERR("BUG! Tx ring full when queue awake!\n");
+		if (txdata->tx_ring_size == 0) {
+			struct bnx2x_eth_q_stats *q_stats =
+				bnx2x_fp_qstats(bp, txdata->parent_fp);
+			q_stats->driver_filtered_tx_pkt++;
+			dev_kfree_skb(skb);
+			return NETDEV_TX_OK;
+		}
 			bnx2x_fp_qstats(bp, txdata->parent_fp)->driver_xoff++;
 			netif_tx_stop_queue(txq);
-		}
+		BNX2X_ERR("BUG! Tx ring full when queue awake!\n");
 
 		return NETDEV_TX_BUSY;
 	}

drivers/net/ethernet/broadcom/bnx2x/bnx2x_ethtool.c

@@ -62,7 +62,9 @@ static const struct {
 						8, "[%s]: tpa_aggregations" },
 	{ Q_STATS_OFFSET32(total_tpa_aggregated_frames_hi),
 					8, "[%s]: tpa_aggregated_frames"},
-	{ Q_STATS_OFFSET32(total_tpa_bytes_hi),	8, "[%s]: tpa_bytes"}
+	{ Q_STATS_OFFSET32(total_tpa_bytes_hi),	8, "[%s]: tpa_bytes"},
+	{ Q_STATS_OFFSET32(driver_filtered_tx_pkt),
+					4, "[%s]: driver_filtered_tx_pkt" }
 };
 
 #define BNX2X_NUM_Q_STATS ARRAY_SIZE(bnx2x_q_stats_arr)
@@ -177,6 +179,8 @@ static const struct {
 			4, STATS_FLAGS_FUNC, "recoverable_errors" },
 	{ STATS_OFFSET32(unrecoverable_error),
 			4, STATS_FLAGS_FUNC, "unrecoverable_errors" },
+	{ STATS_OFFSET32(driver_filtered_tx_pkt),
+			4, STATS_FLAGS_FUNC, "driver_filtered_tx_pkt" },
 	{ STATS_OFFSET32(eee_tx_lpi),
 			4, STATS_FLAGS_PORT, "Tx LPI entry count"}
 };

drivers/net/ethernet/broadcom/bnx2x/bnx2x_stats.c

@@ -1149,6 +1149,7 @@ static void bnx2x_drv_stats_update(struct bnx2x *bp)
 		UPDATE_ESTAT_QSTAT(rx_err_discard_pkt);
 		UPDATE_ESTAT_QSTAT(rx_skb_alloc_failed);
 		UPDATE_ESTAT_QSTAT(hw_csum_err);
+		UPDATE_ESTAT_QSTAT(driver_filtered_tx_pkt);
 	}
 }
 

drivers/net/ethernet/broadcom/bnx2x/bnx2x_stats.h

@@ -203,6 +203,7 @@ struct bnx2x_eth_stats {
 	/* Recovery */
 	u32 recoverable_error;
 	u32 unrecoverable_error;
+	u32 driver_filtered_tx_pkt;
 	/* src: Clear-on-Read register; Will not survive PMF Migration */
 	u32 eee_tx_lpi;
 };
@@ -264,6 +265,7 @@ struct bnx2x_eth_q_stats {
 	u32 total_tpa_aggregated_frames_lo;
 	u32 total_tpa_bytes_hi;
 	u32 total_tpa_bytes_lo;
+	u32 driver_filtered_tx_pkt;
 };
 
 struct bnx2x_eth_stats_old {
@@ -315,6 +317,7 @@ struct bnx2x_eth_q_stats_old {
 	u32 rx_err_discard_pkt_old;
 	u32 rx_skb_alloc_failed_old;
 	u32 hw_csum_err_old;
+	u32 driver_filtered_tx_pkt_old;
 };
 
 struct bnx2x_net_stats_old {