i40e: add helper to copy statistic values into ethtool buffer

Similar to the helper function to copy the ethtool stats strings, add
and use a helper function for copying the ethtool stats into the
supplied buffer.

Just like before, we use a macro to avoid having to pass ARRAY_SIZE
manually, so as to reduce chance of bugs.

Some of the stats, especially queue stats, are a bit trickier, and will
be handled in future patches.
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

@@ -1705,6 +1705,89 @@ static int i40e_get_sset_count(struct net_device *netdev, int sset)
 	}
 }
 
+/**
+ * i40e_add_one_ethtool_stat - copy the stat into the supplied buffer
+ * @data: location to store the stat value
+ * @pointer: basis for where to copy from
+ * @stat: the stat definition
+ *
+ * Copies the stat data defined by the pointer and stat structure pair into
+ * the memory supplied as data. Used to implement i40e_add_ethtool_stats.
+ * If the pointer is null, data will be zero'd.
+ */
+static inline void
+i40e_add_one_ethtool_stat(u64 *data, void *pointer,
+			  const struct i40e_stats *stat)
+{
+	char *p;
+
+	if (!pointer) {
+		/* ensure that the ethtool data buffer is zero'd for any stats
+		 * which don't have a valid pointer.
+		 */
+		*data = 0;
+		return;
+	}
+
+	p = (char *)pointer + stat->stat_offset;
+	switch (stat->sizeof_stat) {
+	case sizeof(u64):
+		*data = *((u64 *)p);
+		break;
+	case sizeof(u32):
+		*data = *((u32 *)p);
+		break;
+	case sizeof(u16):
+		*data = *((u16 *)p);
+		break;
+	case sizeof(u8):
+		*data = *((u8 *)p);
+		break;
+	default:
+		WARN_ONCE(1, "unexpected stat size for %s",
+			  stat->stat_string);
+		*data = 0;
+	}
+}
+
+/**
+ * __i40e_add_ethtool_stats - copy stats into the ethtool supplied buffer
+ * @data: ethtool stats buffer
+ * @pointer: location to copy stats from
+ * @stats: array of stats to copy
+ * @size: the size of the stats definition
+ *
+ * Copy the stats defined by the stats array using the pointer as a base into
+ * the data buffer supplied by ethtool. Updates the data pointer to point to
+ * the next empty location for successive calls to __i40e_add_ethtool_stats.
+ * If pointer is null, set the data values to zero and update the pointer to
+ * skip these stats.
+ **/
+static inline void
+__i40e_add_ethtool_stats(u64 **data, void *pointer,
+			 const struct i40e_stats stats[],
+			 const unsigned int size)
+{
+	unsigned int i;
+
+	for (i = 0; i < size; i++)
+		i40e_add_one_ethtool_stat((*data)++, pointer, &stats[i]);
+}
+
+/**
+ * i40e_add_ethtool_stats - copy stats into ethtool supplied buffer
+ * @data: ethtool stats buffer
+ * @pointer: location where stats are stored
+ * @stats: static const array of stat definitions
+ *
+ * Macro to ease the use of __i40e_add_ethtool_stats by taking a static
+ * constant stats array and passing the ARRAY_SIZE(). This avoids typos by
+ * ensuring that we pass the size associated with the given stats array.
+ * Assumes that stats is an array.
+ **/
+#define i40e_add_ethtool_stats(data, pointer, stats) \
+	__i40e_add_ethtool_stats(data, pointer, stats, ARRAY_SIZE(stats))
+
 /**
  * i40e_get_ethtool_stats - copy stat values into supplied buffer
  * @netdev: the netdev to collect stats for
@@ -1727,22 +1810,15 @@ static void i40e_get_ethtool_stats(struct net_device *netdev,
 	struct i40e_vsi *vsi = np->vsi;
 	struct i40e_pf *pf = vsi->back;
 	unsigned int i;
-	char *p;
-	struct rtnl_link_stats64 *net_stats = i40e_get_vsi_stats_struct(vsi);
 	unsigned int start;
 
 	i40e_update_stats(vsi);
 
-	for (i = 0; i < I40E_NETDEV_STATS_LEN; i++) {
-		p = (char *)net_stats + i40e_gstrings_net_stats[i].stat_offset;
-		*(data++) = (i40e_gstrings_net_stats[i].sizeof_stat ==
-			sizeof(u64)) ? *(u64 *)p : *(u32 *)p;
-	}
-	for (i = 0; i < I40E_MISC_STATS_LEN; i++) {
-		p = (char *)vsi + i40e_gstrings_misc_stats[i].stat_offset;
-		*(data++) = (i40e_gstrings_misc_stats[i].sizeof_stat ==
-			    sizeof(u64)) ? *(u64 *)p : *(u32 *)p;
-	}
+	i40e_add_ethtool_stats(&data, i40e_get_vsi_stats_struct(vsi),
+			       i40e_gstrings_net_stats);
+
+	i40e_add_ethtool_stats(&data, vsi, i40e_gstrings_misc_stats);
+
 	rcu_read_lock();
 	for (i = 0; i < I40E_MAX_NUM_QUEUES(netdev) ; i++) {
 		tx_ring = READ_ONCE(vsi->tx_rings[i]);
@@ -1783,12 +1859,8 @@ static void i40e_get_ethtool_stats(struct net_device *netdev,
 	    (pf->flags & I40E_FLAG_VEB_STATS_ENABLED)) {
 		struct i40e_veb *veb = pf->veb[pf->lan_veb];
 
-		for (i = 0; i < I40E_VEB_STATS_LEN; i++) {
-			p = (char *)veb;
-			p += i40e_gstrings_veb_stats[i].stat_offset;
-			*(data++) = (i40e_gstrings_veb_stats[i].sizeof_stat ==
-				     sizeof(u64)) ? *(u64 *)p : *(u32 *)p;
-		}
+		i40e_add_ethtool_stats(&data, veb, i40e_gstrings_veb_stats);
+
 		for (i = 0; i < I40E_MAX_TRAFFIC_CLASS; i++) {
 			*(data++) = veb->tc_stats.tc_tx_packets[i];
 			*(data++) = veb->tc_stats.tc_tx_bytes[i];
@@ -1798,11 +1870,9 @@ static void i40e_get_ethtool_stats(struct net_device *netdev,
 	} else {
 		data += I40E_VEB_STATS_TOTAL;
 	}
-	for (i = 0; i < I40E_GLOBAL_STATS_LEN; i++) {
-		p = (char *)pf + i40e_gstrings_stats[i].stat_offset;
-		*(data++) = (i40e_gstrings_stats[i].sizeof_stat ==
-			     sizeof(u64)) ? *(u64 *)p : *(u32 *)p;
-	}
+
+	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];