Re: [for-next][PATCH 1/5] tracepoint: Give priority to probes of tracepoints

From: Steven Rostedt
Date: Fri Oct 30 2015 - 16:25:44 EST

On Thu, 29 Oct 2015 17:52:16 +0000 (UTC)
Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx> wrote:

> ----- On Oct 29, 2015, at 3:07 AM, rostedt rostedt@xxxxxxxxxxx wrote:
> > From: "Steven Rostedt (Red Hat)" <rostedt@xxxxxxxxxxx>
> >
> > In order to guarantee that a probe will be called before other probes that
> > are attached to a tracepoint, there needs to be a mechanism to provide
> > priority of one probe over the others.
> >
> > Adding a prio field to the struct tracepoint_func, which lets the probes be
> > sorted by the priority set in the structure. If no priority is specified,
> > then a priority of 10 is given (this is a macro, and perhaps may be changed
> > in the future).
> >
> > Now probes may be added to affect other probes that are attached to a
> > tracepoint with a guaranteed order.
> >
> > One use case would be to allow tracing of tracepoints be able to filter by
> > pid. A special (higher priority probe) may be added to the sched_switch
> > tracepoint and set the necessary flags of the other tracepoints to notify
> > them if they should be traced or not. In case a tracepoint is enabled at the
> > sched_switch tracepoint too, the order of the two are not random.
> >
> > Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
> > Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
> Sounds good to me,
> Acked-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>


Unfortunately I already pushed it out to linux-next (had a deadline),
otherwise I could have added your ack. I'm guessing you missed the RFC
version I posted a week ago.

-- Steve

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