Re: [PATCH][next] mtd: rawnand: Replace one-element array with flexible-array member

Stefan Agner
2020-10-01T09:23:18Z

On 2020-10-01 10:12, Miquel Raynal wrote:
> Hi Jann,
>
> Jann Horn <jannh@google.com> wrote on Thu, 1 Oct 2020 00:32:24 +0200:
>
>> On Wed, Sep 30, 2020 at 11:30 PM Gustavo A. R. Silva
>> <gustavoars@kernel.org> wrote:
>> > On Wed, Sep 30, 2020 at 11:10:43PM +0200, Jann Horn wrote:
>> > > On Wed, Sep 30, 2020 at 11:02 PM Gustavo A. R. Silva
>> > > <gustavoars@kernel.org> wrote:
>> > > > 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].
>> > >
>> > > But this is not such a case, right? Isn't this a true fixed-size
>> > > array? It sounds like you're just changing it because it
>> > > pattern-matched on "array of length 1 at the end of a struct".
>> >
>> > Yeah; I should have changed that 'dynamically' part of the text above
>> > a bit. However, as I commented in the text below, in the case that more
>> > CS IDs are needed (let's wait for the maintainers to comment on this...)
>> > in the future, this change makes the code more maintainable, as for
>> > the allocation part, the developer would only have to update the CS_N
>> > macro to the number of CS IDs that are needed.
>>
>> But in that case, shouldn't you change it to "int cs[CS_N]" and get
>> rid of the struct_size() stuff?
>
> I do agree with Jann, I think it's best to consider this a fixed-size
> array for now. If we ever want to extend the number of supported CS,
> there is much more rework involved anyway.

I agree, too, just assume this is a fixed-size array of 1 element.

In fact, I am not aware of a design which needs multiple chip selects.

--
Stefan