Messages in this thread | | | From | Arnd Bergmann <> | Subject | Re: [PATCH 15/15] OF: remove #ifdef from linux/of_platform.h | Date | Tue, 4 Jun 2013 19:51:00 +0200 |
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On Tuesday 04 June 2013, Rob Herring wrote: > On Sat, Jun 1, 2013 at 3:57 PM, Arnd Bergmann <arnd@arndb.de> wrote: > > On Saturday 01 June 2013, Rob Herring wrote: > >> No, we still need empty functions. Here is what of_device.h looks like: > >> > >> http://tinyurl.com/l2azz5m > >> > >> BTW, it has your ack. > >> > > > > Could you add a patch on top that only puts the function declarations > > inside of #ifdef that don't have an inline wrapper? > > I'm confused. You mean that DO have an inline? Like this: > > void foo(void); > > #ifdef CONFIG_OF > void bar(void); > #else > static inline void bar(void) {} > #endif
Yes, sorry. That's what I meant.
> > It's really annoying to have to change the header file every time one > > needs to call a function from a driver in the DT-only case. > > The functions without inlines are ones that drivers should not call > and should only be called from OF enabled code. That's why we have not > done a complete pass of adding inlines for everything.
The problem is that it's a bad default. The convention in kernel code is not to hide declarations in #ifdef, for multiple reasons:
* It avoids unnecessary code rebuilds when the symbol changes between two 'make' runs.
* It lets drivers and platform code call the function from dead code without causing a build error, thus improving compile coverage.
* It's much nicer to read when can write your code like
void __init exynos_init_io(struct map_desc *mach_desc, int size) { if (IS_ENABLED_(CONFIG_OF) && initial_boot_params) of_scan_flat_dt(exynos_fdt_map_chipid, NULL); else iotable_init(exynos_iodesc, ARRAY_SIZE(exynos_iodesc)); ... }
instead of
void __init exynos_init_io(struct map_desc *mach_desc, int size) { #ifdef CONFIG_OF if (initial_boot_params) of_scan_flat_dt(exynos_fdt_map_chipid, NULL); else #endif iotable_init(exynos_iodesc, ARRAY_SIZE(exynos_iodesc)); ... }
The first one looks like actual C code, the second is really ugly, and an inline wrapper wouldn't even do the right thing here.
Arnd
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