linux-kernel - Re: [PATCH] Partially revert "compiler: enable CONFIG_OPTIMIZE

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Date:   Tue, 1 Oct 2019 11:42:54 +0100
From:   Will Deacon <will@...nel.org>
To:     Masahiro Yamada <yamada.masahiro@...ionext.com>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Nicolas Saenz Julienne <nsaenzjulienne@...e.de>,
        Catalin Marinas <catalin.marinas@....com>,
        Russell King <linux@...linux.org.uk>,
        Arnd Bergmann <arnd@...db.de>
Subject: Re: [PATCH] Partially revert "compiler: enable
 CONFIG_OPTIMIZE_INLINING forcibly"

On Tue, Oct 01, 2019 at 06:40:26PM +0900, Masahiro Yamada wrote:
> On Mon, Sep 30, 2019 at 8:45 PM Will Deacon <will@...nel.org> wrote:
> > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> > index 93d97f9b0157..c37c72adaeff 100644
> > --- a/lib/Kconfig.debug
> > +++ b/lib/Kconfig.debug
> > @@ -312,6 +312,7 @@ config HEADERS_CHECK
> >
> >  config OPTIMIZE_INLINING
> >         def_bool y
> > +       depends on !(ARM || ARM64) # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91111
> 
> 
> This is a too big hammer.

It matches the previous default behaviour!

> For ARM, it is not a compiler bug, so I am trying to fix the kernel code.
> 
> For ARM64, even if it is a compiler bug, you can add __always_inline
> to the functions in question.
> (arch_atomic64_dec_if_positive in this case).
> 
> You do not need to force __always_inline globally.

So you'd prefer I do something like the diff below? I mean, it's a start,
but I do worry that we're hanging arch/arm/ out to dry.

Will

--->8

diff --git a/arch/arm64/include/asm/atomic_lse.h b/arch/arm64/include/asm/atomic_lse.h
index c6bd87d2915b..574808b9df4c 100644
--- a/arch/arm64/include/asm/atomic_lse.h
+++ b/arch/arm64/include/asm/atomic_lse.h
@@ -321,7 +321,8 @@ static inline s64 __lse_atomic64_dec_if_positive(atomic64_t *v)
 }
 
 #define __CMPXCHG_CASE(w, sfx, name, sz, mb, cl...)                    \
-static inline u##sz __lse__cmpxchg_case_##name##sz(volatile void *ptr, \
+static __always_inline u##sz                                           \
+__lse__cmpxchg_case_##name##sz(volatile void *ptr,                     \
                                              u##sz old,                \
                                              u##sz new)                \
 {                                                                      \
@@ -362,7 +363,8 @@ __CMPXCHG_CASE(x,  ,  mb_, 64, al, "memory")
 #undef __CMPXCHG_CASE
 
 #define __CMPXCHG_DBL(name, mb, cl...)                                 \
-static inline long __lse__cmpxchg_double##name(unsigned long old1,     \
+static __always_inline long                                            \
+__lse__cmpxchg_double##name(unsigned long old1,                                \
                                         unsigned long old2,            \
                                         unsigned long new1,            \
                                         unsigned long new2,            \