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    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().

    [1] https://en.wikipedia.org/wiki/Flexible_array_member
    [2] https://www.kernel.org/doc/html/v5.9-rc1/process/deprecated.html#zero-length-and-one-element-arrays

    Build-tested-by: kernel test robot <lkp@intel.com>
    Link: https://lore.kernel.org/lkml/5f7473c0.Vv4h6yzXSga90P04%25lkp@intel.com/
    Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
    ---
    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 @@
    HWSTATUS_RBSY_MASK(NAND_STATUS_READY) | \
    HWSTATUS_RBSY_VALUE(NAND_STATUS_READY))

    +/* 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;

    --
    2.27.0
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