Re: [LTP] [PATCH] Fix disable set_ftrace_pid in ftrace_set_ftrace_pid.sh

[Han Pingtian <phan@redhat.com>]

On Mon, Feb 21, 2011 at 03:44:11PM +0800, Li Zefan wrote:
> Han Pingtian wrote:
> > It seems we need echo -1 to set_ftrace_pid to disable in. Or we'll get
> > these error message when running ftrace_stress:
> > 
> 
> kernel version?
2.6.32-114.0.1.el6.x86_64 , RHEL6.1.
> 
> This is the result from latest kernel:
> 
> # echo > set_ftrace_pid
> # echo -1 > set_ftrace_pid
> bash: echo: write error: Invalid argument
> 
Looks like latest kernel changed the behaviour. But the
Documentation/trace/ftrace.txt hasn't been updated:

     yum-updatesd-3111  [003]  1637.254683: lock_hrtimer_base <-hrtimer_try_to_cancel
     yum-updatesd-3111  [003]  1637.254685: fget_light <-do_sys_poll
     yum-updatesd-3111  [003]  1637.254686: pipe_poll <-do_sys_poll
# echo -1 > set_ftrace_pid
# cat trace |head
 # tracer: function
 #
 #           TASK-PID    CPU#    TIMESTAMP  FUNCTION
 

Thanks.
> > ...
> > ftrace_stress_test/ftrace_stress/ftrace_set_ftrace_pid.sh: line 39: echo: write error: Invalid argument
> > ...
> > ---
> >  .../ftrace_stress/ftrace_set_ftrace_pid.sh         |    2 +-
> >  1 files changed, 1 insertions(+), 1 deletions(-)
> > 
> > diff --git a/testcases/kernel/tracing/ftrace_stress_test/ftrace_stress/ftrace_set_ftrace_pid.sh b/testcases/kernel/tracing/ftrace_stress_test/ftrace_stress/ftrace_set_ftrace_pid.sh
> > index 541215c..bd08f04 100755
> > --- a/testcases/kernel/tracing/ftrace_stress_test/ftrace_stress/ftrace_set_ftrace_pid.sh
> > +++ b/testcases/kernel/tracing/ftrace_stress_test/ftrace_stress/ftrace_set_ftrace_pid.sh
> > @@ -36,7 +36,7 @@ for ((; ; ))
> >  			eval echo $str >> "$TRACING_PATH"/set_ftrace_pid
> >  		}
> >  
> > -		echo > "$TRACING_PATH"/set_ftrace_pid
> > +		echo -1 > "$TRACING_PATH"/set_ftrace_pid
> >  	}
> >  
> >  	sleep 1

-- 
Han Pingtian
Quality Engineer
hpt @ #kernel-qe
Red Hat, Inc
Freedom ... courage ... Commitment ... ACCOUNTABILITY

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