On Fri, 19 Jan 2007, Pekka Enberg wrote:
> On 1/19/07, Robert P. J. Day <[email protected]> wrote:
> > is there a simple explanation for how to *properly* define inline
> > routines in the kernel? and maybe this can be added to the
> > CodingStyle guide (he mused, wistfully).
>
> AFAIK __always_inline is the only reliable way to force inlining
> where it matters for correctness (for example, when playing tricks
> with __builtin_return_address like we do in the slab).
>
> Anything else is just a hint to the compiler that might be ignored
> if the optimizer thinks it knows better.
oh, *that* part i knew. what i don't understand is the difference
between "inline", "__inline" and "__inline__". you can see in
include/linux/compiler-gcc4.h:
#ifdef CONFIG_FORCED_INLINING
# undef inline
# undef __inline__
# undef __inline
# define inline inline __attribute__((always_inline))
# define __inline__ __inline__ __attribute__((always_inline))
# define __inline __inline __attribute__((always_inline))
#endif
so that header file certainly suggests that there's some sort of
difference. after which it gets even more confusing as various macros
seem to mix and match:
drivers/cdrom/sbpcd.c:#define INLINE inline
arch/arm/nwfpe/ARM-gcc.h:#define INLINE extern __inline__
arch/cris/arch-v10/kernel/fasttimer.c:#define __INLINE__ inline
arch/alpha/mm/fault.c:#define __EXTERN_INLINE inline
... etc etc ...
i mean, how many different kinds of inline *are* there?
rday
p.s. apparently, some of the alpha people are less than thrilled with
the situation:
include/asm-alpha/compiler.h:
-----------------------------
#ifdef __KERNEL__
/* Some idiots over in <linux/compiler.h> thought inline should imply
always_inline. This breaks stuff. We'll include this file whenever
we run into such problems. */
#include <linux/compiler.h>
#undef inline
#undef __inline__
#undef __inline
#undef __always_inline
#define __always_inline inline __attribute__((always_inline))
#endif /* __KERNEL__ */
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
