Re: [discuss] [2.6 patch] include/asm-x86_64 "extern inline" -> "static inline"

H. Peter Anvin
2005-09-06T04:39:08Z

Followup to: <20050905190014.GB3776@stusta.de>
By author: Adrian Bunk <bunk@stusta.de>
In newsgroup: linux.dev.kernel
>
> On Mon, Sep 05, 2005 at 02:47:40PM -0400, Jakub Jelinek wrote:
> > On Mon, Sep 05, 2005 at 08:00:05PM +0200, Adrian Bunk wrote:
> > > It isn't the same, but "static inline" is the correct variant.
> > >
> > > "extern inline __attribute__((always_inline))" (which is what
> > > "extern inline" is expanded to) doesn't make sense.
> >
> > It does make sense and is different from
> > static inline __attribute__((always_inline)).
> > Try:
> > static inline __attribute__((always_inline)) void foo (void) {}
> > void (*fn)(void) = foo;
> > vs.
> > extern inline __attribute__((always_inline)) void foo (void) {}
> > void (*fn)(void) = foo;
> > In the former case, GCC will emit the out of line static copy of foo
> > if you take its address, in the latter case either you provide foo
> > function by other means, or you get linker error.
>
> And we need the former case because in the kernel we do not have
> out-of-line variants of the inline functions.
>

UNLESS the function is broken if out-of-lined. If the function cannot
be safely out-of-lined, extern inline MUST be used.

-hpa