Re: [for-next][PATCH 00/18] function_graph: Add separate depth counter to prevent trace corruption

[Joe Lawrence]

On Wed, Nov 21, 2018 at 07:28:01PM -0500, Steven Rostedt wrote:
>
> [ ... snip ... ]
>
> Feel free to test this! I'll be pushing this to linux-next and let it
> sit there a week or so before pushing it to Linus.
>
>   git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
> ftrace/urgent

Hi Steve,

With your ftrace/urgent branch linked above, if I try a quick
function_graph test like the following:

  SYSFS=/sys/kernel/debug/tracing

  echo 0 > "$SYSFS/tracing_on"
  echo cmdline_proc_show > "$SYSFS/set_graph_function"
  echo function_graph > "$SYSFS/current_tracer"
  echo 1 > "$SYSFS/tracing_on"

I see a bunch of scheduler interrupt functions in the trace/trace_pipe
without even invoking cmdline_proc_show().

This tests works as expected with Linux 4.20-rc3 though:

  % cat /sys/kernel/debug/tracing/trace_pipe
   2)               |  cmdline_proc_show() {
   2)   0.320 us    |    seq_puts();
   2)   0.030 us    |    seq_putc();
   2)   1.352 us    |  }

Operator error, or did the patchset break something?

Regards,

-- Joe