From: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Date: Tue, 27 Oct 2020 16:30:45 -0500
Subject: gve: Replace zero-length array with flexible-array member
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Patch-mainline: v5.10-rc2
Git-commit: 691f4077d5604af4067ebbea4a27f05e760557b7
References: bsc#1176940

There is a regular need in the kernel to provide a way to declare having a
dynamically sized set of trailing elements in a structure.  Kernel code
should always use “flexible array members”[1] for these cases.  The
older style of one-element or zero-length arrays should no longer be
used[2].

Refactor the code according to the use of a flexible-array member in
struct gve_stats_report, instead of a zero-length array, and use the
struct_size() helper to calculate the size for the resource allocation.

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.9/process/deprecated.html#zero-length-and-one-element-arrays

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/google/gve/gve_adminq.h |    2 +-
 drivers/net/ethernet/google/gve/gve_main.c   |    5 ++---
 2 files changed, 3 insertions(+), 4 deletions(-)

--- a/drivers/net/ethernet/google/gve/gve_adminq.h
+++ b/drivers/net/ethernet/google/gve/gve_adminq.h
@@ -183,7 +183,7 @@ struct stats {
 
 struct gve_stats_report {
 	__be64 written_count;
-	struct stats stats[0];
+	struct stats stats[];
 };
 
 
--- a/drivers/net/ethernet/google/gve/gve_main.c
+++ b/drivers/net/ethernet/google/gve/gve_main.c
@@ -116,9 +116,8 @@ static int gve_alloc_stats_report(struct
 		       priv->tx_cfg.num_queues;
 	rx_stats_num = (GVE_RX_STATS_REPORT_NUM + NIC_RX_STATS_REPORT_NUM) *
 		       priv->rx_cfg.num_queues;
-	priv->stats_report_len = sizeof(struct gve_stats_report) +
-				 (tx_stats_num + rx_stats_num) *
-				 sizeof(struct stats);
+	priv->stats_report_len = struct_size(priv->stats_report, stats,
+					     tx_stats_num + rx_stats_num);
 	priv->stats_report =
 		dma_alloc_coherent(&priv->pdev->dev, priv->stats_report_len,
 				   &priv->stats_report_bus, GFP_KERNEL);