On Thu, Feb 14, 2019 at 03:05:20PM -0500, Steven Rostedt wrote:
> On Thu, 14 Feb 2019 16:13:28 +0200
> Slavomir Kaslev <kaslevs@xxxxxxxxxx> wrote:
>
> > Add BUFFER_FL_GUEST and BUFFER_FL_AGENT flags to differentiate when
> > trace-record.c is being called to trace guest or the VM tracing agent.
> >
> > Also disable functions talking to the local tracefs when called in recording
> > guest instances context.
> >
> > Signed-off-by: Slavomir Kaslev <kaslevs@xxxxxxxxxx>
> > ---
> > tracecmd/include/trace-local.h | 2 ++
> > tracecmd/trace-record.c | 55 ++++++++++++++++++++++++++++++++--
> > 2 files changed, 55 insertions(+), 2 deletions(-)
> >
> > diff --git a/tracecmd/include/trace-local.h b/tracecmd/include/trace-local.h
> > index a1a06e9..f19c8bb 100644
> > --- a/tracecmd/include/trace-local.h
> > +++ b/tracecmd/include/trace-local.h
> > @@ -149,6 +149,8 @@ char *strstrip(char *str);
> > enum buffer_instance_flags {
> > BUFFER_FL_KEEP = 1 << 0,
> > BUFFER_FL_PROFILE = 1 << 1,
> > + BUFFER_FL_GUEST = 1 << 2,
> > + BUFFER_FL_AGENT = 1 << 3,
> > };
> >
> > struct func_list {
> > diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
> > index 8beefab..107d3d1 100644
> > --- a/tracecmd/trace-record.c
> > +++ b/tracecmd/trace-record.c
> > @@ -781,6 +781,9 @@ static void __clear_trace(struct buffer_instance *instance)
> > FILE *fp;
> > char *path;
> >
> > + if (instance->flags & BUFFER_FL_GUEST)
> > + return;
> > +
> > /* reset the trace */
> > path = get_instance_file(instance, "trace");
> > fp = fopen(path, "w");
> > @@ -1264,6 +1267,9 @@ set_plugin_instance(struct buffer_instance *instance, const char *name)
> > char *path;
> > char zero = '0';
> >
> > + if (instance->flags & BUFFER_FL_GUEST)
> > + return;
> > +
> > path = get_instance_file(instance, "current_tracer");
> > fp = fopen(path, "w");
> > if (!fp) {
> > @@ -1360,6 +1366,9 @@ static void disable_func_stack_trace_instance(struct buffer_instance *instance)
> > int size;
> > int ret;
> >
> > + if (instance->flags & BUFFER_FL_GUEST)
> > + return;
> > +
> > path = get_instance_file(instance, "current_tracer");
> > ret = stat(path, &st);
> > tracecmd_put_tracing_file(path);
>
>
> I think we should add a:
>
> #define is_guest(instance) ((instance)->flags & BUFFER_FL_GUEST)
>
> Helper macro here, and all these should be turned into:
>
> if (is_guest(instance))
> return;
>
> Less error prone, and looks cleaner.
>
> We could add a is_agent() too in later patches.
Makes sense. I added both is_agent and is_guest for the next iteration of this
patchset.
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