Re: [patch V2 22/29] tracing: Make ftrace_trace_userstack() static and conditional

[Steven Rostedt <rostedt@goodmis.org>]

On Thu, 18 Apr 2019 10:41:41 +0200
Thomas Gleixner <tglx@linutronix.de> wrote:

> It's only used in trace.c and there is absolutely no point in compiling it
> in when user space stack traces are not supported.
> 
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Cc: Steven Rostedt <rostedt@goodmis.org>

Funny, these were moved out to global functions along with the
ftrace_trace_stack() but I guess they were never used.

This basically just does a partial revert of:

 c0a0d0d3f6528 ("tracing/core: Make the stack entry helpers global")


> ---
>  kernel/trace/trace.c |   14 ++++++++------
>  kernel/trace/trace.h |    8 --------
>  2 files changed, 8 insertions(+), 14 deletions(-)
> 
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -159,6 +159,8 @@ static union trace_eval_map_item *trace_
>  #endif /* CONFIG_TRACE_EVAL_MAP_FILE */
>  
>  static int tracing_set_tracer(struct trace_array *tr, const char *buf);
> +static void ftrace_trace_userstack(struct ring_buffer *buffer,
> +				   unsigned long flags, int pc);
>  
>  #define MAX_TRACER_SIZE		100
>  static char bootup_tracer_buf[MAX_TRACER_SIZE] __initdata;
> @@ -2905,9 +2907,10 @@ void trace_dump_stack(int skip)
>  }
>  EXPORT_SYMBOL_GPL(trace_dump_stack);
>  
> +#ifdef CONFIG_USER_STACKTRACE_SUPPORT
>  static DEFINE_PER_CPU(int, user_stack_count);
>  
> -void
> +static void
>  ftrace_trace_userstack(struct ring_buffer *buffer, unsigned long flags, int pc)
>  {
>  	struct trace_event_call *call = &event_user_stack;
> @@ -2958,13 +2961,12 @@ ftrace_trace_userstack(struct ring_buffe
>   out:
>  	preempt_enable();
>  }
> -
> -#ifdef UNUSED

Strange, I never knew about this ifdef. I would have nuked it when I
saw it.

Anyway,

Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

-- Steve


> -static void __trace_userstack(struct trace_array *tr, unsigned long flags)
> +#else /* CONFIG_USER_STACKTRACE_SUPPORT */
> +static void ftrace_trace_userstack(struct ring_buffer *buffer,
> +				   unsigned long flags, int pc)
>  {
> -	ftrace_trace_userstack(tr, flags, preempt_count());
>  }
> -#endif /* UNUSED */
> +#endif /* !CONFIG_USER_STACKTRACE_SUPPORT */
>  
>  #endif /* CONFIG_STACKTRACE */
>  
> --- a/kernel/trace/trace.h
> +++ b/kernel/trace/trace.h
> @@ -782,17 +782,9 @@ void update_max_tr_single(struct trace_a
>  #endif /* CONFIG_TRACER_MAX_TRACE */
>  
>  #ifdef CONFIG_STACKTRACE
> -void ftrace_trace_userstack(struct ring_buffer *buffer, unsigned long flags,
> -			    int pc);
> -
>  void __trace_stack(struct trace_array *tr, unsigned long flags, int skip,
>  		   int pc);
>  #else
> -static inline void ftrace_trace_userstack(struct ring_buffer *buffer,
> -					  unsigned long flags, int pc)
> -{
> -}
> -
>  static inline void __trace_stack(struct trace_array *tr, unsigned long flags,
>  				 int skip, int pc)
>  {
>