Re: [PATCH] compiler: enable CONFIG_OPTIMIZE_INLINING forcibly

[Masahiro Yamada]

On Sat, Oct 12, 2019 at 7:21 PM Stefan Wahren <wahrenst@xxxxxxx> wrote:
>
> Hi,
>
> Am 03.10.19 um 18:36 schrieb Will Deacon:
> > On Wed, Oct 02, 2019 at 01:39:40PM -0700, Linus Torvalds wrote:
> >> On Wed, Oct 2, 2019 at 5:56 AM Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote:
> >>>> Then use the C preprocessor to force the inlining.  I'm sorry it's not
> >>>> as pretty as static inline functions.
> >>> Which makes us lose the baby^H^H^H^Htype checking performed
> >>> on function parameters, requiring to add more ugly checks.
> >> I'm 100% agreed on this.
> >>
> >> If the inline change is being pushed by people who say "you should
> >> have used macros instead if you wanted inlining", then I will just
> >> revert that stupid commit that is causing problems.
> >>
> >> No, the preprocessor is not the answer.
> >>
> >> That said, code that relies on inlining for _correctness_ should use
> >> "__always_inline" and possibly even have a comment about why.
> >>
> >> But I am considering just undoing commit 9012d011660e ("compiler:
> >> allow all arches to enable CONFIG_OPTIMIZE_INLINING") entirely. The
> >> advantages are questionable, and when the advantages are balanced
> >> against actual regressions and the arguments are "use macros", that
> >> just shows how badly thought out this was.
> > It's clear that opinions are divided on this issue, but you can add
> > an enthusiastic:
> >
> > Acked-by: Will Deacon <will@xxxxxxxxxx>
> >
> > if you go ahead with the revert. I'm all for allowing the compiler to
> > make its own inlining decisions, but not when the potential for
> > miscompilation isn't fully understood and the proposed alternatives turn
> > the source into an unreadable mess. Perhaps we can do something different
> > for 5.5 (arch opt-in? clang only? invert the logic? work to move functions
> > over to __always_inline /before/ flipping the CONFIG option? ...?)
>
> what's the status on this?
>
> In need to prepare my pull requests for 5.5 and all recent kernelci
> targets (including linux-next) with bcm2835_defconfig are still broken.
>
> Stefan


Russell King already applied the fix-up patch.

https://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=8908/1

So, (I hope) the breakage of bcm2835 will be solved in mainline soon.





-- 
Best Regards
Masahiro Yamada