i40e: convert priority flow control stats to use helpers

The priority flow control statistics are laid out in the stats structure
using arrays. This made it unwieldy to use as part of an i40e_stats
array.

Add a new structure type, i40e_pfc_stats, and a helper function
i40e_get_pfc_stats which can return the stats for a given priority
value as an i40e_pfc_stats structure.

Use this to create an i40e_stats array, which we'll use to format and
copy the strings and stats into the supplied buffers.

This reduces even more boiler plate code in i40e_get_ethtool_stats and
i40e_get_stat_strings.

An alternative would be to modify the structure definition for the pfc
stats, but this is more invasive to the rest of the code base.

Note that a macro was used to setup the copy of stats from the
pf->stats, as this reduces the chance of typos in the code names. It
will produce a checkpatch.pl warning due to re-use of a macro argument.
In this case, it should be safe, as the macro will fail to compile in
cases where the argument is not a simple structure member name, and thus
arguments with side effects should not be an issue.

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/i40e/i40e_ethtool.c

@@ -31,6 +31,8 @@ struct i40e_stats {
 	I40E_STAT(struct i40e_vsi, _name, _stat)
 #define I40E_VEB_STAT(_name, _stat) \
 	I40E_STAT(struct i40e_veb, _name, _stat)
+#define I40E_PFC_STAT(_name, _stat) \
+	I40E_STAT(struct i40e_pfc_stats, _name, _stat)
 
 static const struct i40e_stats i40e_gstrings_net_stats[] = {
 	I40E_NETDEV_STAT(rx_packets),
@@ -153,6 +155,22 @@ static const struct i40e_stats i40e_gstrings_stats[] = {
 	I40E_PF_STAT("port.rx_lpi_count", stats.rx_lpi_count),
 };
 
+struct i40e_pfc_stats {
+	u64 priority_xon_rx;
+	u64 priority_xoff_rx;
+	u64 priority_xon_tx;
+	u64 priority_xoff_tx;
+	u64 priority_xon_2_xoff;
+};
+
+static const struct i40e_stats i40e_gstrings_pfc_stats[] = {
+	I40E_PFC_STAT("port.tx_priority_%u_xon_tx", priority_xon_tx),
+	I40E_PFC_STAT("port.tx_priority_%u_xoff_tx", priority_xoff_tx),
+	I40E_PFC_STAT("port.rx_priority_%u_xon_rx", priority_xon_rx),
+	I40E_PFC_STAT("port.rx_priority_%u_xoff_rx", priority_xoff_rx),
+	I40E_PFC_STAT("port.rx_priority_%u_xon_2_xoff", priority_xon_2_xoff),
+};
+
 /* We use num_tx_queues here as a proxy for the maximum number of queues
  * available because we always allocate queues symmetrically.
  */
@@ -167,13 +185,9 @@ static const struct i40e_stats i40e_gstrings_stats[] = {
 #define I40E_VSI_STATS_LEN(n)	(I40E_NETDEV_STATS_LEN + \
 				 I40E_MISC_STATS_LEN + \
 				 I40E_QUEUE_STATS_LEN((n)))
-#define I40E_PFC_STATS_LEN ( \
-		(FIELD_SIZEOF(struct i40e_pf, stats.priority_xoff_rx) + \
-		 FIELD_SIZEOF(struct i40e_pf, stats.priority_xon_rx) + \
-		 FIELD_SIZEOF(struct i40e_pf, stats.priority_xoff_tx) + \
-		 FIELD_SIZEOF(struct i40e_pf, stats.priority_xon_tx) + \
-		 FIELD_SIZEOF(struct i40e_pf, stats.priority_xon_2_xoff)) \
-		 / sizeof(u64))
+
+#define I40E_PFC_STATS_LEN	(ARRAY_SIZE(i40e_gstrings_pfc_stats) * \
+				 I40E_MAX_USER_PRIORITY)
 
 #define I40E_VEB_STATS_LEN	(ARRAY_SIZE(i40e_gstrings_veb_stats) + \
 				 (ARRAY_SIZE(i40e_gstrings_veb_tc_stats) * \
@@ -1798,6 +1812,31 @@ __i40e_add_ethtool_stats(u64 **data, void *pointer,
 #define i40e_add_ethtool_stats(data, pointer, stats) \
 	__i40e_add_ethtool_stats(data, pointer, stats, ARRAY_SIZE(stats))
 
+/**
+ * i40e_get_pfc_stats - copy HW PFC statistics to formatted structure
+ * @pf: the PF device structure
+ * @i: the priority value to copy
+ *
+ * The PFC stats are found as arrays in pf->stats, which is not easy to pass
+ * into i40e_add_ethtool_stats. Produce a formatted i40e_pfc_stats structure
+ * of the PFC stats for the given priority.
+ **/
+static inline struct i40e_pfc_stats
+i40e_get_pfc_stats(struct i40e_pf *pf, unsigned int i)
+{
+#define I40E_GET_PFC_STAT(stat, priority) \
+	.stat = pf->stats.stat[priority]
+
+	struct i40e_pfc_stats pfc = {
+		I40E_GET_PFC_STAT(priority_xon_rx, i),
+		I40E_GET_PFC_STAT(priority_xoff_rx, i),
+		I40E_GET_PFC_STAT(priority_xon_tx, i),
+		I40E_GET_PFC_STAT(priority_xoff_tx, i),
+		I40E_GET_PFC_STAT(priority_xon_2_xoff, i),
+	};
+	return pfc;
+}
+
 /**
  * i40e_get_ethtool_stats - copy stat values into supplied buffer
  * @netdev: the netdev to collect stats for
@@ -1884,15 +1923,10 @@ static void i40e_get_ethtool_stats(struct net_device *netdev,
 	i40e_add_ethtool_stats(&data, pf, i40e_gstrings_stats);
 
 	for (i = 0; i < I40E_MAX_USER_PRIORITY; i++) {
-		*(data++) = pf->stats.priority_xon_tx[i];
-		*(data++) = pf->stats.priority_xoff_tx[i];
-	}
-	for (i = 0; i < I40E_MAX_USER_PRIORITY; i++) {
-		*(data++) = pf->stats.priority_xon_rx[i];
-		*(data++) = pf->stats.priority_xoff_rx[i];
+		struct i40e_pfc_stats pfc = i40e_get_pfc_stats(pf, i);
+
+		i40e_add_ethtool_stats(&data, &pfc, i40e_gstrings_pfc_stats);
 	}
-	for (i = 0; i < I40E_MAX_USER_PRIORITY; i++)
-		*(data++) = pf->stats.priority_xon_2_xoff[i];
 }
 
 /**
@@ -1973,27 +2007,8 @@ static void i40e_get_stat_strings(struct net_device *netdev, u8 *data)
 
 	i40e_add_stat_strings(&data, i40e_gstrings_stats);
 
-	for (i = 0; i < I40E_MAX_USER_PRIORITY; i++) {
-		snprintf(data, ETH_GSTRING_LEN,
-			 "port.tx_priority_%u_xon", i);
-		data += ETH_GSTRING_LEN;
-		snprintf(data, ETH_GSTRING_LEN,
-			 "port.tx_priority_%u_xoff", i);
-		data += ETH_GSTRING_LEN;
-	}
-	for (i = 0; i < I40E_MAX_USER_PRIORITY; i++) {
-		snprintf(data, ETH_GSTRING_LEN,
-			 "port.rx_priority_%u_xon", i);
-		data += ETH_GSTRING_LEN;
-		snprintf(data, ETH_GSTRING_LEN,
-			 "port.rx_priority_%u_xoff", i);
-		data += ETH_GSTRING_LEN;
-	}
-	for (i = 0; i < I40E_MAX_USER_PRIORITY; i++) {
-		snprintf(data, ETH_GSTRING_LEN,
-			 "port.rx_priority_%u_xon_2_xoff", i);
-		data += ETH_GSTRING_LEN;
-	}
+	for (i = 0; i < I40E_MAX_USER_PRIORITY; i++)
+		i40e_add_stat_strings(&data, i40e_gstrings_pfc_stats, i);
 
 	WARN_ONCE(p - data != i40e_get_stats_count(netdev) * ETH_GSTRING_LEN,
 		  "stat strings count mismatch!");