Re: [GIT PULL] MFD fixes for v5.2

Lee Jones
2019-06-18T08:15:59Z

On Mon, 17 Jun 2019, Linus Torvalds wrote:

> On Mon, Jun 17, 2019 at 3:01 AM Lee Jones <lee.jones@linaro.org> wrote:
> >
> > Enjoy!
>
> No.
>
> This is still entirely wrong.
>
> You can't just randomly cast an "u32 *" to "unsigned long *".
>
> It wasn't correct when you did it the other way in regmap_read(), but
> it's also not correct when you now for it this way for
> for_each_set_bit().
>
> You can do
>
> u32 regmap_bits;
> unsigned long bits;
>
> and then
>
> ret = regmap_read(stmfx->map, STMFX_REG_IRQ_PENDING, &regmap_bits);
> ...
> bits = regmap_bits;
> for_each_set_bit(n, &bits, STMFX_REG_IRQ_SRC_MAX) ..
>
> but casting pointers at either point is *completely* wrong.
>
> Yes, yes, it happens to work on little-endian, but on a 64-bit
> big-endian machine, the low 32 bits of the "unsigned int" will have
> absolutely _zero_ overlap with the low 32 bits of the "unsigned long"
> in memory.
>
> When you moved the cast to for_each_set_bit(), it only moves the
> access of the bogus bits to another place instead.
>
> So that patch doesn't fix anything at all, it only moves the same error around.

Good catch. Thank you for taking the time to review Linus.

--
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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