Re: [RFC][PATCH 00/21] tracing: Inter-event (e.g. latency) support

Steven Rostedt
2017-02-09T02:24:18Z

On Wed, 08 Feb 2017 17:28:50 -0600
Tom Zanussi <tom.zanussi@linux.intel.com> wrote:

> On Wed, 2017-02-08 at 15:01 -0500, Steven Rostedt wrote:
> > On Wed, 8 Feb 2017 11:24:56 -0600
> > Tom Zanussi <tom.zanussi@linux.intel.com> wrote:
> >
> > > # echo 'wakeup_latency lat=sched_switch:wakeup_lat \
> > > pid=sched_switch:woken_pid \
> > > prio=sched_switch:woken_prio' >> \
> > > /sys/kernel/debug/tracing/synthetic_events
> >
> > I applied all your patches, did the above and then:
> >
> > BUG: unable to handle kernel NULL pointer dereference at 0000000000000034
> > IP: free_synthetic_event+0x46/0xb0
> > PGD 0
> >
>
> OK, well, the problem is actually the '\' 'continuation' characters in
> the above string. I'll fix that properly, but in the meantime, removing
> those chars in the documentation strings will let you try it out i.e.
>
> # echo 'wakeup_latency lat=sched_switch:wakeup_lat pid=sched_switch:woken_pid prio=sched_switch:woken_prio' >> /sys/kernel/debug/tracing/synthetic_events

Ah, OK. Yeah, I did a cut and paste when entering it.

-- Steve