Am Freitag, den 09.11.2012, 10:32 +0800 schrieb Yuanhan Liu:
> On Thu, Nov 08, 2012 at 01:37:15PM +0100, Stefani Seibold wrote:
> > Am Donnerstag, den 08.11.2012, 20:24 +0800 schrieb Yuanhan Liu:
> Yes, it is. I will try log API then.
>
> Stefani, I found an issue while rework to current API. Say the current
> code of __kfifo_init:
> int __kfifo_init(struct __kfifo *fifo, void *buffer,
> unsigned int size, size_t esize)
> {
> size /= esize;
>
> if (!is_power_of_2(size))
> size = rounddown_pow_of_two(size);
> ....
> }
>
> Even thought I changed the API to something like:
> int __kfifo_init(struct __kfifo *fifo, void *buffer,
> int size_order, size_t esize)
> {
> unsigned int size = 1 << size_order;
>
> size /= esize;
> ...
> }
>
> See? There is still a divide and we can't make it sure that it will be
> power of 2 after that.
>
> So, I came up 2 proposal to fix this.
>
> 1. refactor the meaning of 'size' argument first.
>
> 'size' means the size of pre-allocated buffer. We can refactor it to
> meaning of 'the number of fifo elements' just like __kfifo_alloc, so
> that we don't need do the size /= esize stuff.
>
> 2. remove kfifo_init
>
> As we can't make sure that kfifo will do exactly what users asked(in
> the way of fifo size). It would be safe and good to maintain buffer
> and buffer size inside kfifo. So, I propose to remove it and use
> kfifo_alloc instead.
>
> git grep 'kfifo_init\>' shows that we currently have 2 users only.
>
>
> The first way is hacky, and it doesn't make much sense to me. Since
> buffer is pre-allocated by user but not kfifo. User has to calculate
> element size and the number of elements, which is not friendly.
>
> The second way does make more sense to me.
kfifo_init() was requested by some kernel developers, i never liked it.
If you have a better and cleaner solution than do it, otherwise kick it
away if you like.
- Stefani
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