ixgbe: add statistic indicating number of skipped Tx timestamps

The ixgbe driver can only handle one Tx timestamp request at a time.
This means it is possible for an application timestamp request to be
ignored.

There is no easy way for an administrator to determine if this occurred.
Add a new statistic which tracks this, tx_hwtstamp_skipped.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/ixgbe/ixgbe.h

@@ -733,6 +733,7 @@ struct ixgbe_adapter {
 	struct timecounter hw_tc;
 	u32 base_incval;
 	u32 tx_hwtstamp_timeouts;
+	u32 tx_hwtstamp_skipped;
 	u32 rx_hwtstamp_cleared;
 	void (*ptp_setup_sdp)(struct ixgbe_adapter *);
 

drivers/net/ethernet/intel/ixgbe/ixgbe_ethtool.c

@@ -111,6 +111,9 @@ static const struct ixgbe_stats ixgbe_gstrings_stats[] = {
 	{"os2bmc_tx_by_bmc", IXGBE_STAT(stats.b2ospc)},
 	{"os2bmc_tx_by_host", IXGBE_STAT(stats.o2bspc)},
 	{"os2bmc_rx_by_host", IXGBE_STAT(stats.b2ogprc)},
+	{"tx_hwtstamp_timeouts", IXGBE_STAT(tx_hwtstamp_timeouts)},
+	{"tx_hwtstamp_skipped", IXGBE_STAT(tx_hwtstamp_skipped)},
+	{"rx_hwtstamp_cleared", IXGBE_STAT(rx_hwtstamp_cleared)},
 #ifdef IXGBE_FCOE
 	{"fcoe_bad_fccrc", IXGBE_STAT(stats.fccrc)},
 	{"rx_fcoe_dropped", IXGBE_STAT(stats.fcoerpdc)},

drivers/net/ethernet/intel/ixgbe/ixgbe_main.c

@@ -8337,8 +8337,8 @@ netdev_tx_t ixgbe_xmit_frame_ring(struct sk_buff *skb,
 	protocol = vlan_get_protocol(skb);
 
 	if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP) &&
-	    adapter->ptp_clock &&
-	    !test_and_set_bit_lock(__IXGBE_PTP_TX_IN_PROGRESS,
+	    adapter->ptp_clock) {
+		if (!test_and_set_bit_lock(__IXGBE_PTP_TX_IN_PROGRESS,
 					   &adapter->state)) {
 			skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS;
 			tx_flags |= IXGBE_TX_FLAGS_TSTAMP;
@@ -8347,6 +8347,9 @@ netdev_tx_t ixgbe_xmit_frame_ring(struct sk_buff *skb,
 			adapter->ptp_tx_skb = skb_get(skb);
 			adapter->ptp_tx_start = jiffies;
 			schedule_work(&adapter->ptp_tx_work);
+		} else {
+			adapter->tx_hwtstamp_skipped++;
+		}
 	}
 
 	skb_tx_timestamp(skb);