[PATCH net-next 04/21] ethernet, dpaa2: simplify per-channel Ethtool stats counting

[Alexander Lobakin]

Don't hardcode ARRAY_SIZE() - 1, just put a placeholder and take
offsetof() from it to hide unwanted statistics from Ethtool.
Will be handy for switching to standard XDP stats.

Signed-off-by: Alexander Lobakin <alexandr.lobakin@xxxxxxxxx>
Reviewed-by: Jesse Brandeburg <jesse.brandeburg@xxxxxxxxx>
---
 drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.h     | 7 ++++++-
 drivers/net/ethernet/freescale/dpaa2/dpaa2-ethtool.c | 2 +-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.h b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.h
index cdb623d5f2c1..8cb57f103d6b 100644
--- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.h
+++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.h
@@ -382,10 +382,15 @@ struct dpaa2_eth_ch_stats {
 	__u64 xdp_tx;
 	__u64 xdp_tx_err;
 	__u64 xdp_redirect;
-	/* Must be last, does not show up in ethtool stats */
+	/* The rest of the structure does not show up in ethtool stats */
+	struct { } __eth_end;
+	/* Must be last */
 	__u64 frames;
 };
 
+#define DPAA2_ETH_NUM_CH_STATS		(offsetof(struct dpaa2_eth_ch_stats, \
+						  __eth_end) / sizeof(u64))
+
 /* Maximum number of queues associated with a DPNI */
 #define DPAA2_ETH_MAX_TCS		8
 #define DPAA2_ETH_MAX_RX_QUEUES_PER_TC	16
diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-ethtool.c b/drivers/net/ethernet/freescale/dpaa2/dpaa2-ethtool.c
index ad5e374eeccf..95ae83905458 100644
--- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-ethtool.c
+++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-ethtool.c
@@ -278,7 +278,7 @@ static void dpaa2_eth_get_ethtool_stats(struct net_device *net_dev,
 	/* Per-channel stats */
 	for (k = 0; k < priv->num_channels; k++) {
 		ch_stats = &priv->channel[k]->stats;
-		for (j = 0; j < sizeof(*ch_stats) / sizeof(__u64) - 1; j++)
+		for (j = 0; j < DPAA2_ETH_NUM_CH_STATS; j++)
 			*((__u64 *)data + i + j) += *((__u64 *)ch_stats + j);
 	}
 	i += j;
-- 
2.31.1