Re: [RFC][PATCH] tracing: Replace '-' with '_' in event system names

From: Cornelia Huck
Date: Wed Apr 01 2015 - 06:37:14 EST

On Tue, 31 Mar 2015 23:18:02 -0400
Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:

> There's a change I want to make to the tracing infrastructure that may
> require TRACE_SYSTEM be a valid variable name. As '-' can not be used
> in a variable, and I found only three cases that it is a TRACE_SYSTEM
> name, I want to ask those that are responsible if it is OK to change
> them?
> The three systems are:
> #define TRACE_SYSTEM kvm-s390
> #define TRACE_SYSTEM xhci-hcd
> #define TRACE_SYSTEM intel-sst
> I want to replace the '-' with '_'. But this will have a user space
> visible affect, which is why I'm inquiring with you. If this will break
> any scripts or annoy any users that you know of, I'll need to make a
> work around (which would not be hard to do). But if I don't need to do
> that, I prefer to just use TRACE_SYSTEM as is.
> I'll just do the work around if there is any user space tool that you
> know of that will break with this change.
> The effect is that the directories in /sys/kernel/debug/tracing/events/
> will be different. That is,
> /sys/kernel/debug/tracing/events/kvm-s390/
> will become
> /sys/kernel/debug/tracing/events/kvm_s390/
> And the same for the other two. Is this a problem?

The only direct dependency for kvm-s390 I'm aware of is in
perf/tests/parse-events.c, added because parsing an event with '-' in
the name was broken.

Otherwise, I'm not aware of things that should break, excluding local
scripts and so on of course.

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