[PATCH 6.6.y] gve: Correct ethtool rx_dropped calculation

[Sasha Levin <sashal@kernel.org>]

From: Max Yuan <maxyuan@google.com>

[ Upstream commit c7db85d579a1dccb624235534508c75fbf2dfe46 ]

The gve driver's "rx_dropped" statistic, exposed via `ethtool -S`,
incorrectly includes `rx_buf_alloc_fail` counts. These failures
represent an inability to allocate receive buffers, not true packet
drops where a received packet is discarded. This misrepresentation can
lead to inaccurate diagnostics.

This patch rectifies the ethtool "rx_dropped" calculation. It removes
`rx_buf_alloc_fail` from the total and adds `xdp_tx_errors` and
`xdp_redirect_errors`, which represent legitimate packet drops within
the XDP path.

Cc: stable@vger.kernel.org
Fixes: 433e274b8f7b ("gve: Add stats for gve.")
Signed-off-by: Max Yuan <maxyuan@google.com>
Reviewed-by: Jordan Rhee <jordanrhee@google.com>
Reviewed-by: Joshua Washington <joshwash@google.com>
Reviewed-by: Matt Olson <maolson@google.com>
Signed-off-by: Harshitha Ramamurthy <hramamurthy@google.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/20260202193925.3106272-3-hramamurthy@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
[ Adjust context ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/ethernet/google/gve/gve_ethtool.c | 26 ++++++++++++++-----
 1 file changed, 19 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/google/gve/gve_ethtool.c b/drivers/net/ethernet/google/gve/gve_ethtool.c
index 22317acf16ba4..997e1d7736a84 100644
--- a/drivers/net/ethernet/google/gve/gve_ethtool.c
+++ b/drivers/net/ethernet/google/gve/gve_ethtool.c
@@ -156,9 +156,11 @@ gve_get_ethtool_stats(struct net_device *netdev,
 {
 	u64 tmp_rx_pkts, tmp_rx_bytes, tmp_rx_skb_alloc_fail,
 		tmp_rx_buf_alloc_fail, tmp_rx_desc_err_dropped_pkt,
-		tmp_tx_pkts, tmp_tx_bytes;
+		tmp_tx_pkts, tmp_tx_bytes,
+		tmp_xdp_tx_errors, tmp_xdp_redirect_errors;
 	u64 rx_buf_alloc_fail, rx_desc_err_dropped_pkt, rx_pkts,
-		rx_skb_alloc_fail, rx_bytes, tx_pkts, tx_bytes, tx_dropped;
+		rx_skb_alloc_fail, rx_bytes, tx_pkts, tx_bytes, tx_dropped,
+		xdp_tx_errors, xdp_redirect_errors;
 	int stats_idx, base_stats_idx, max_stats_idx;
 	struct stats *report_stats;
 	int *rx_qid_to_stats_idx;
@@ -186,7 +188,8 @@ gve_get_ethtool_stats(struct net_device *netdev,
 		return;
 	}
 	for (rx_pkts = 0, rx_bytes = 0, rx_skb_alloc_fail = 0,
-	     rx_buf_alloc_fail = 0, rx_desc_err_dropped_pkt = 0, ring = 0;
+	     rx_buf_alloc_fail = 0, rx_desc_err_dropped_pkt = 0,
+	     xdp_tx_errors = 0, xdp_redirect_errors = 0, ring = 0;
 	     ring < priv->rx_cfg.num_queues; ring++) {
 		if (priv->rx) {
 			do {
@@ -200,6 +203,9 @@ gve_get_ethtool_stats(struct net_device *netdev,
 				tmp_rx_buf_alloc_fail = rx->rx_buf_alloc_fail;
 				tmp_rx_desc_err_dropped_pkt =
 					rx->rx_desc_err_dropped_pkt;
+				tmp_xdp_tx_errors = rx->xdp_tx_errors;
+				tmp_xdp_redirect_errors =
+					rx->xdp_redirect_errors;
 			} while (u64_stats_fetch_retry(&priv->rx[ring].statss,
 						       start));
 			rx_pkts += tmp_rx_pkts;
@@ -207,6 +213,8 @@ gve_get_ethtool_stats(struct net_device *netdev,
 			rx_skb_alloc_fail += tmp_rx_skb_alloc_fail;
 			rx_buf_alloc_fail += tmp_rx_buf_alloc_fail;
 			rx_desc_err_dropped_pkt += tmp_rx_desc_err_dropped_pkt;
+			xdp_tx_errors += tmp_xdp_tx_errors;
+			xdp_redirect_errors += tmp_xdp_redirect_errors;
 		}
 	}
 	for (tx_pkts = 0, tx_bytes = 0, tx_dropped = 0, ring = 0;
@@ -231,8 +239,8 @@ gve_get_ethtool_stats(struct net_device *netdev,
 	data[i++] = rx_bytes;
 	data[i++] = tx_bytes;
 	/* total rx dropped packets */
-	data[i++] = rx_skb_alloc_fail + rx_buf_alloc_fail +
-		    rx_desc_err_dropped_pkt;
+	data[i++] = rx_skb_alloc_fail + rx_desc_err_dropped_pkt +
+		    xdp_tx_errors + xdp_redirect_errors;
 	data[i++] = tx_dropped;
 	data[i++] = priv->tx_timeo_cnt;
 	data[i++] = rx_skb_alloc_fail;
@@ -281,6 +289,9 @@ gve_get_ethtool_stats(struct net_device *netdev,
 				tmp_rx_buf_alloc_fail = rx->rx_buf_alloc_fail;
 				tmp_rx_desc_err_dropped_pkt =
 					rx->rx_desc_err_dropped_pkt;
+				tmp_xdp_tx_errors = rx->xdp_tx_errors;
+				tmp_xdp_redirect_errors =
+					rx->xdp_redirect_errors;
 			} while (u64_stats_fetch_retry(&priv->rx[ring].statss,
 						       start));
 			data[i++] = tmp_rx_bytes;
@@ -290,8 +301,9 @@ gve_get_ethtool_stats(struct net_device *netdev,
 			data[i++] = rx->rx_frag_alloc_cnt;
 			/* rx dropped packets */
 			data[i++] = tmp_rx_skb_alloc_fail +
-				tmp_rx_buf_alloc_fail +
-				tmp_rx_desc_err_dropped_pkt;
+				    tmp_rx_desc_err_dropped_pkt +
+				    tmp_xdp_tx_errors +
+				    tmp_xdp_redirect_errors;
 			data[i++] = rx->rx_copybreak_pkt;
 			data[i++] = rx->rx_copied_pkt;
 			/* stats from NIC */
-- 
2.51.0