Re: [PATCH] kernel: trace: remove __init from race_selftest_startup_function()and trace_selftest_startup_function_graph()

[Chen Gang]

On 07/12/2013 10:38 AM, Steven Rostedt wrote:
> On Fri, 2013-07-12 at 09:58 +0800, Chen Gang wrote:
>> On 07/12/2013 09:41 AM, Steven Rostedt wrote:
>>> On Fri, 2013-07-12 at 07:51 +0800, Chen Gang wrote:
>>>
>>>>> Hmm, can all trace_selftest_startup_* (*selftest* in trace_selftest.c)
>>>>> use '__init', so not waste memory keeping them around ?
>>> Yeah, they should all be set to __init, but that's pretty low on the
>>> totem poll, as distros don't enable selftests in their main kernels.
>>
>> Excuse me, my English is not quite well, I guess your meaning is:
>>
>>   they should all be set to '__init', although it is minor in real world.
>>
>> Is it correct ?
> 
> Correct.
> 
>>
>>
>> For me, I recommend to let all *selftest* as the same: "all add '
>> __init' or none add '__init'" (if choose add, all report warnings).
>>
>> Is it suitable to still send new related patch for it ? If so, could
>> you provide your suggesting choice (all add, or none add) ?
> 
> Does this patch fix your warning?
> 
> -- Steve
> 

I guess it can (although I do not give a compiling test), it seems a
better fixing.

And is it suitable to let all *selftest* as the same ? (all add, or none
add '__init').

Thanks.

> diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
> index a4ed382..5e794d1 100644
> --- a/kernel/trace/trace.h
> +++ b/kernel/trace/trace.h
> @@ -680,6 +680,15 @@ extern int trace_selftest_startup_sched_switch(struct tracer *trace,
>  					       struct trace_array *tr);
>  extern int trace_selftest_startup_branch(struct tracer *trace,
>  					 struct trace_array *tr);
> +/*
> + * Tracer data references selftest functions that only occur
> + * on boot up. These can be __init functions. Thus, when selftests
> + * are enabled, then the tracers need to reference __init functions.
> + */
> +#define __tracer_data		__refdata
> +#else
> +/* Tracers are seldom changed. Optimize when selftests are disabled. */
> +#define __tracer_data		__read_mostly
>  #endif /* CONFIG_FTRACE_STARTUP_TEST */
>  
>  extern void *head_page(struct trace_array_cpu *data);
> diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c
> index b863f93..38fe148 100644
> --- a/kernel/trace/trace_functions.c
> +++ b/kernel/trace/trace_functions.c
> @@ -199,7 +199,7 @@ static int func_set_flag(u32 old_flags, u32 bit, int set)
>  	return 0;
>  }
>  
> -static struct tracer function_trace __read_mostly =
> +static struct tracer function_trace __tracer_data =
>  {
>  	.name		= "function",
>  	.init		= function_trace_init,
> 
> 
> 
> 


-- 
Chen Gang
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