Re: [PATCH] ftrace: using pr_fmt for better printk output

[Jovi Zhang]

On Tue, Jul 17, 2012 at 1:07 PM, Joe Perches <joe@xxxxxxxxxxx> wrote:
> On Tue, 2012-07-17 at 00:25 -0400, Steven Rostedt wrote:
>> On Mon, 2012-07-16 at 20:42 -0700, Joe Perches wrote:
>>
>> > > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
>> > []
>> > > @@ -13,6 +13,8 @@
>> > >   *  Copyright (C) 2004 William Lee Irwin III
>> > >   */
>> > >
>> > > +#define pr_fmt(fmt) "ftrace: " fmt
>> >
>> > #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
>>
>> Wouldn't a nicer patch be to move this into a header file and then
>> remove all the defines throughout the kernel tree?
>
> Maybe.  There are modules that use common header files
> like you suggest.  It does mean that header must be the
> #included before any other #include that might
> #include <linux/kernel.h> or printk.h.
>
> Right now, if pr_fmt isn't #defined, printk.h
> has a default definition of:
>
> #ifndef pr_fmt
> #define pr_fmt(fmt) fmt
> #endif
>
> My goal is to change that to:
>
> #ifndef pr_fmt
> #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> #endif
>
> in 3.8 (maybe 3.7) and remove all of these then
> useless, duplicate #defines shortly afterward.
>
> https://lkml.org/lkml/2012/3/27/247
>
>> Also, what is KBUILD_MODNAME defined as for non-modules? As ftrace is
>> not a module.
>
> It depends on the Makefile.
>
> scripts/Makefile.lib:# $(modname_flags) #defines KBUILD_MODNAME as the name of the module it will
> scripts/Makefile.lib-# end up in (or would, if it gets compiled in)
> scripts/Makefile.lib-# Note: Files that end up in two or more modules are compiled without the
> scripts/Makefile.lib:#       KBUILD_MODNAME definition. The reason is that any made-up name would
> scripts/Makefile.lib-#       differ in different configs.
> scripts/Makefile.lib-name-fix = $(subst $(comma),_,$(subst -,_,$1))
> scripts/Makefile.lib-basename_flags = -D"KBUILD_BASENAME=KBUILD_STR($(call name-fix,$(basetarget)))"
> scripts/Makefile.lib-modname_flags  = $(if $(filter 1,$(words $(modname))),\
> scripts/Makefile.lib:                 -D"KBUILD_MODNAME=KBUILD_STR($(call name-fix,$(modname)))")
>
Hmm, that would make sense, get subsystem name from Makefile.

Joe, there will delete all this pr_fmt definition in .c file in 3.8(or
3.7) as you metioned, so we can ingnore this patch.

.Jovi
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