[PATCH] ARM: ftrace: Trace function entry before updating index

[Steven Rostedt]

On Mon, 2012-07-16 at 19:03 -0700, Colin Cross wrote:
> Commit 722b3c74695377d11d18a52f3da08114d37f3f37 modified x86 ftrace to
> avoid tracing all functions called from irqs when function graph was
> used with a filter.  Port the same fix to ARM.
> 
> Cc: Steven Rostedt <rostedt at goodmis.org>

Acked-by: Steven Rostedt <rostedt at goodmis.org>

Someone on the ARM side needs to pull this in.

I'll look into fixing this for PPC.

Thanks!

-- Steve

> Signed-off-by: Colin Cross <ccross at android.com>
> ---
> 
> It looks like the same issue affects blackfin, microblaze, mips,
> parisc, powerpc, s390, sh, and sparc, but I don't have patches to
> fix those.
> 
>  arch/arm/kernel/ftrace.c |   17 +++++++++--------
>  1 files changed, 9 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c
> index df0bf0c..34e5664 100644
> --- a/arch/arm/kernel/ftrace.c
> +++ b/arch/arm/kernel/ftrace.c
> @@ -179,19 +179,20 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
>  	old = *parent;
>  	*parent = return_hooker;
>  
> -	err = ftrace_push_return_trace(old, self_addr, &trace.depth,
> -				       frame_pointer);
> -	if (err == -EBUSY) {
> -		*parent = old;
> -		return;
> -	}
> -
>  	trace.func = self_addr;
> +	trace.depth = current->curr_ret_stack + 1;
>  
>  	/* Only trace if the calling function expects to */
>  	if (!ftrace_graph_entry(&trace)) {
> -		current->curr_ret_stack--;
>  		*parent = old;
> +		return;
> +	}
> +
> +	err = ftrace_push_return_trace(old, self_addr, &trace.depth,
> +				       frame_pointer);
> +	if (err == -EBUSY) {
> +		*parent = old;
> +		return;
>  	}
>  }
>