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SubjectRE: [PATCH] regulator: da9062: Replace zero-length array with flexible-array member
Date
On 11 February 2020 23:46, Gustavo A. R. Silva wrote:

> The current codebase makes use of the zero-length array language
> extension to the C90 standard, but the preferred mechanism to declare
> variable-length types such as these ones is a flexible array member[1][2],
> introduced in C99:
>
> struct foo {
> int stuff;
> struct boo array[];
> };
>
> By making use of the mechanism above, we will get a compiler warning
> in case the flexible array does not occur last in the structure, which
> will help us prevent some kind of undefined behavior bugs from being
> inadvertenly introduced[3] to the codebase from now on.
>
> This issue was found with the help of Coccinelle.
>
> [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
> [2] https://github.com/KSPP/linux/issues/21
> [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
>
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
> ---
> drivers/regulator/da9062-regulator.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/regulator/da9062-regulator.c b/drivers/regulator/da9062-
> regulator.c
> index b064d8a19d4c..c3b6ba9bafdf 100644
> --- a/drivers/regulator/da9062-regulator.c
> +++ b/drivers/regulator/da9062-regulator.c
> @@ -86,7 +86,7 @@ struct da9062_regulators {
> int irq_ldo_lim;
> unsigned n_regulators;
> /* Array size to be defined during init. Keep at end. */
> - struct da9062_regulator regulator[0];
> + struct da9062_regulator regulator[];

I don't think is the correct change here for this driver. In the probe
'struct_size()' is used to determine the actual size requested from 'malloc()'
when allocating memory for this structure. It's not statically initialised.
Your change will break that code I believe.

> };
>
> /* BUCK modes */
> --
> 2.25.0

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