Re: [PATCH 08/33] x86/fpu: Clarify parameter names in the copy_xstate_to_*() methods

[Thomas Gleixner]

On Sat, 23 Sep 2017, Ingo Molnar wrote:
>  static inline int
>  __copy_xstate_to_kernel(void *kbuf,
>  			const void *data,
> -			unsigned int pos, unsigned int count, int end_pos)
> +			unsigned int offset, unsigned int size, int size_total)

Why is size_total int?

>  {
> -	if (!count)
> +	if (!size)
>  		return 0;
>  
> -	if (end_pos < 0 || pos < end_pos) {
> -		unsigned int copy = end_pos < 0 ? count : min(count, end_pos - pos);
> +	if (size_total < 0 || offset < size_total) {

And why would it be < 0? The call sites of this inline are all inside of:

int copy_xstate_to_kernel(void *kbuf, struct xregs_state *xsave,
    			unsigned int offset_start, int size_total)

and hand in size_total completely unmodified. copy_xstate_to_kernel()
itself has a single callsite:

int xstateregs_get(struct task_struct *target, const struct user_regset *regset,
                unsigned int pos, unsigned int count,
                void *kbuf, void __user *ubuf)

and that hands in count unmodified.

The same issue is with the to_user() variant which is even more
obvious. All callers are inside of copy_xstate_to_user() where size_total
is an unsigned int argument which is handed in unmodified.

This signed/unsigned mismatch is confusing at best.

Thanks,

	tglx