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Date:   Wed, 30 Sep 2020 16:08:24 -0500
From:   "Gustavo A. R. Silva" <>
To:     Stefan Agner <>, Lucas Stach <>,
        Miquel Raynal <>,
        Richard Weinberger <>,
        Vignesh Raghavendra <>,
        Thierry Reding <>,
        Jonathan Hunter <>
        "Gustavo A. R. Silva" <>,
Subject: [PATCH][next] mtd: rawnand: Replace one-element array with
 flexible-array member

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
instead of a one-element array. Also, make use of the struct_size()
helper to calculate the size of the allocation for _nand_. In order
to keep the code as maintainable as possible and to keep _cs_ as an
array, add a new macro CS_N to aid in the allocation size calculation,
in case there is a need for more Chip Select IDs in the future. In the
meantime, the macro is set to 1. This also avoids having to use a magic
number '1' as the last argument for struct_size().


Build-tested-by: kernel test robot <>
Signed-off-by: Gustavo A. R. Silva <>
 drivers/mtd/nand/raw/tegra_nand.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/mtd/nand/raw/tegra_nand.c b/drivers/mtd/nand/raw/tegra_nand.c
index fbf67722a049..43b8359dcd85 100644
--- a/drivers/mtd/nand/raw/tegra_nand.c
+++ b/drivers/mtd/nand/raw/tegra_nand.c
@@ -163,6 +163,9 @@
+/* Number of Chip Selects. Currently, only one. */
+#define CS_N			1
 struct tegra_nand_controller {
 	struct nand_controller controller;
 	struct device *dev;
@@ -183,7 +186,7 @@ struct tegra_nand_chip {
 	u32 config;
 	u32 config_ecc;
 	u32 bch_config;
-	int cs[1];
+	int cs[];
 static inline struct tegra_nand_controller *
@@ -1086,14 +1089,14 @@ static int tegra_nand_chips_init(struct device *dev,
 		return -EINVAL;
-	/* Retrieve CS id, currently only single die NAND supported */
+	/* Retrieve CS id, currently only single-die NAND supported */
 	ret = of_property_read_u32(np_nand, "reg", &cs);
 	if (ret) {
 		dev_err(dev, "could not retrieve reg property: %d\n", ret);
 		return ret;
-	nand = devm_kzalloc(dev, sizeof(*nand), GFP_KERNEL);
+	nand = devm_kzalloc(dev, struct_size(nand, cs, CS_N), GFP_KERNEL);
 	if (!nand)
 		return -ENOMEM;

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