linux-kernel - Re: [PATCH] ftrace: Handle TRACE_BPUTS in print_graph

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Date:   Thu, 1 Sep 2016 12:20:56 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Namhyung Kim <namhyung@...nel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...nel.org>
Subject: Re: [PATCH] ftrace: Handle TRACE_BPUTS in print_graph_comment

On Thu,  1 Sep 2016 11:43:54 +0900
Namhyung Kim <namhyung@...nel.org> wrote:

> It missed to handle TRACE_BPUTS so messages recorded by trace_bputs()
> will be shown with symbol info unnecessarily.
> 
> You can see it with the trace_printk sample code:
> 
>   # cd /sys/kernel/tracing/
>   # echo sys_sync > set_graph_function
>   # echo 1 > options/sym-offset
>   # echo function_graph > current_tracer
> 
> Note that the sys_sync filter was there to prevent recording other
> functions and the sym-offset option was needed since the first message
> was called from a module init function so kallsyms doesn't have the
> symbol and omitted in the output.
> 
>   # cd ~/build/kernel
>   # insmod samples/trace_printk/trace-printk.ko
> 
>   # cd -
>   # head trace
> 
> Before:
> 
>   # tracer: function_graph
>   #
>   # CPU  DURATION                  FUNCTION CALLS
>   # |     |   |                     |   |   |   |
>    1)               |  /* 0xffffffffa0002000: This is a static string that will use trace_bputs */
>    1)               |  /* This is a dynamic string that will use trace_puts */
>    1)               |  /* trace_printk_irq_work+0x5/0x7b [trace_printk]: (irq) This is a static string that will use trace_bputs */
>    1)               |  /* (irq) This is a dynamic string that will use trace_puts */
>    1)               |  /* (irq) This is a static string that will use trace_bprintk() */
>    1)               |  /* (irq) This is a dynamic string that will use trace_printk */
> 
> After:
> 
>   # tracer: function_graph
>   #
>   # CPU  DURATION                  FUNCTION CALLS
>   # |     |   |                     |   |   |   |
>    1)               |  /* This is a static string that will use trace_bputs */
>    1)               |  /* This is a dynamic string that will use trace_puts */
>    1)               |  /* (irq) This is a static string that will use trace_bputs */
>    1)               |  /* (irq) This is a dynamic string that will use trace_puts */
>    1)               |  /* (irq) This is a static string that will use trace_bprintk() */
>    1)               |  /* (irq) This is a dynamic string that will use trace_printk */
> 
> Signed-off-by: Namhyung Kim <namhyung@...nel.org>
> ---

Applied, thanks Namhyung!

-- Steve