Re: [PATCH 0/8] [GIT PULL] TRACE_EVENT for modules

[Jeremy Fitzhardinge <jeremy@goop.org>]

Steven Rostedt wrote:
> On Tue, 14 Apr 2009, Jeremy Fitzhardinge wrote:
>
>   
>> Theodore Tso wrote:
>>     
>>> Any chance you could support something like this?
>>>
>>>   
>>>       
>> I think that's already there.  I'm defining
>> arch/x86/include/asm/paravirt-trace.h with:
>>
>> #ifndef _ASM_X86_PARAVIRT_TRACE_H
>> #define _ASM_X86_PARAVIRT_TRACE_H
>>
>> #include <linux/tracepoint.h>
>> #include <asm/paravirt_types.h>
>>
>> #undef TRACE_SYSTEM
>> #define TRACE_SYSTEM pvops
>>
>> #define TRACE_INCLUDE_FILE	paravirt-trace
>> #define TRACE_INCLUDE_PATH	asm
>> [...]
>>
>>
>> Which ends up including <asm/paravirt-trace.h>
>>     
>
> Not quite. It ends up looking like
>
> #include "asm/paravirt-trace.h"
>
> As long as there is no "asm" directory in the include/trace directory, I 
> think that is fine.

OK.

I'm having a bit of trouble with paravirt-trace.h when I actually 
include it in paravirt.h.  asm/paravirt.h is itself included in lots of 
places, and so its fairly easy to end up with cyclic include 
dependencies which are fairly painful.  In this case I'm seeing 
asm/paravirt.h -> linux/tracepoint.h -> linux/rcupate.h -> {lots of 
stuff}, which gives errors like:

  CC      arch/x86/kernel/asm-offsets.s
In file included from /home/jeremy/git/linux/include/linux/thread_info.h:55,
                 from /home/jeremy/git/linux/include/linux/preempt.h:9,
                 from /home/jeremy/git/linux/include/linux/spinlock.h:50,
                 from /home/jeremy/git/linux/include/linux/rcupdate.h:37,
                 from /home/jeremy/git/linux/include/linux/tracepoint.h:18,
                 from /home/jeremy/git/linux/arch/x86/include/asm/paravirt-trace.h:4,
                 from /home/jeremy/git/linux/arch/x86/include/asm/paravirt.h:18,
                 from /home/jeremy/git/linux/arch/x86/include/asm/irqflags.h:55,
                 from /home/jeremy/git/linux/include/linux/irqflags.h:57,
                 from /home/jeremy/git/linux/arch/x86/include/asm/system.h:11,
                 from /home/jeremy/git/linux/arch/x86/include/asm/processor.h:17,
                 from /home/jeremy/git/linux/include/linux/prefetch.h:14,
                 from /home/jeremy/git/linux/include/linux/list.h:6,
                 from /home/jeremy/git/linux/include/linux/module.h:9,
                 from /home/jeremy/git/linux/include/linux/crypto.h:21,
                 from /home/jeremy/git/linux/arch/x86/kernel/asm-offsets_64.c:7,
                 from /home/jeremy/git/linux/arch/x86/kernel/asm-offsets.c:4:
/home/jeremy/git/linux/arch/x86/include/asm/thread_info.h:34: error: expected specifier-qualifier-list before 'mm_segment_t'



I'm wondering if there's much downside in making the code __DO_TRACE() 
out of line so that we can make tracepoint.h have absolutely minimal 
include dependencies?

    J