On Tue, May 30, 2023 at 12:19:10PM -0700, Jakub Kicinski wrote:
> On Tue, 30 May 2023 14:39:53 +0200 Andrew Lunn wrote:
> > > Therefore we should try to fix phy_read_poll_timeout() instead to
> > > use a local variable like it does for __ret.
> >
> > The problem with that is val is supposed to be available to the
> > caller. I don't know if it is every actually used, but if it is, using
> > an internal signed variable and then throwing away the sign bit on
> > return is going to result in similar bugs.
>
> This is what I meant FWIW:
>
> diff --git a/include/linux/phy.h b/include/linux/phy.h
> index 7addde5d14c0..829bd57b8794 100644
> --- a/include/linux/phy.h
> +++ b/include/linux/phy.h
> @@ -1206,10 +1206,13 @@ static inline int phy_read(struct phy_device *phydev, u32 regnum)
> #define phy_read_poll_timeout(phydev, regnum, val, cond, sleep_us, \
> timeout_us, sleep_before_read) \
> ({ \
> - int __ret = read_poll_timeout(phy_read, val, val < 0 || (cond), \
> + int __ret, __val; \
> + \
> + __ret = read_poll_timeout(phy_read, __val, __val < 0 || (cond), \
> sleep_us, timeout_us, sleep_before_read, phydev, regnum); \
> - if (val < 0) \
> - __ret = val; \
> + val = __val;
> + if (__val < 0) \
> + __ret = __val; \
> if (__ret) \
> phydev_err(phydev, "%s failed: %d\n", __func__, __ret); \
> __ret; \
>
>
> I tried enabling -Wtype-limits but it's _very_ noisy :(
Yes, looks good, that's what I thought you were meaning, and I totally
agree with it. Thanks!
Whatever we decide for this will also need to be applied to
phy_read_mmd_poll_timeout() as well.
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