Re: [PATCH v2 06/12] tracing: Add synthetic event command generation functions

[Tom Zanussi]

Hi Steve,

On Tue, 2020-01-21 at 11:57 -0500, Steven Rostedt wrote:
> On Fri, 10 Jan 2020 14:35:12 -0600
> Tom Zanussi <zanussi@xxxxxxxxxx> wrote:
> 
> > Add functions used to generate synthetic event commands, built on
> > top
> > of the dynevent_cmd interface.
> > 
> > gen_synth_cmd() is used to create a synthetic event command using a
> > variable arg list and gen_synth_cmd_array() does the same thing but
> > using an array of field descriptors.  add_synth_field() and
> > add_synth_fields() can be used to add single fields one by one or
> > as a
> > group.  Once all desired fields are added, create_dynevent() is
> > used
> > to actually execute the command and create the event.
> > 
> > create_synth_event() does everything, including creating the event,
> > in
> > a single call.
> > 
> > Signed-off-by: Tom Zanussi <zanussi@xxxxxxxxxx>
> > ---
> >  include/linux/trace_events.h     |  30 ++++
> >  kernel/trace/trace_events_hist.c | 325
> > ++++++++++++++++++++++++++++++++++++++-
> >  2 files changed, 352 insertions(+), 3 deletions(-)
> > 
> > diff --git a/include/linux/trace_events.h
> > b/include/linux/trace_events.h
> > index bf4cc2e56125..4228407d4736 100644
> > --- a/include/linux/trace_events.h
> > +++ b/include/linux/trace_events.h
> > @@ -409,6 +409,36 @@ extern int create_dynevent(struct dynevent_cmd
> > *cmd);
> >  
> >  extern int delete_synth_event(const char *name);
> >  
> > +extern void synth_dynevent_cmd_init(struct dynevent_cmd *cmd,
> > +				    char *buf, int maxlen);
> > +
> > +extern int __gen_synth_cmd(struct dynevent_cmd *cmd, const char
> > *name,
> > +			   struct module *mod, ...);
> > +
> > +#define gen_synth_cmd(cmd, name, mod, ...)	\
> > +	__gen_synth_cmd(cmd, name, mod, ## __VA_ARGS__, NULL)
> > +
> > +struct synth_field_desc {
> > +	const char *type;
> > +	const char *name;
> > +};
> > +
> > +extern int gen_synth_cmd_array(struct dynevent_cmd *cmd, const
> > char *name,
> > +			       struct module *mod,
> > +			       struct synth_field_desc *fields,
> > +			       unsigned int n_fields);
> > +extern int create_synth_event(const char *name,
> > +			      struct synth_field_desc *fields,
> > +			      unsigned int n_fields, struct module
> > *mod);
> > +
> > +
> > +extern int add_synth_field(struct dynevent_cmd *cmd,
> > +			   const char *type,
> > +			   const char *name);
> > +extern int add_synth_fields(struct dynevent_cmd *cmd,
> > +			    struct synth_field_desc *fields,
> > +			    unsigned int n_fields);
> 
> As these are in a global header and globally visible, let's rename
> them
> to be more name space aware.
> 
> Have them all start with "synth_event_".
> 
> synth_event_gen_cmd_array()
> synth_event_create()
> synth_event_add_field()
> synth_event_add_fields()
> 
> Makes it easier to grep for synth_event functions too.
> 

OK, will do.

Thanks,

Tom

> -- Steve
> 
> 
> > +
> >  /*
> >   * Event file flags:
> >   *  ENABLED	  - The event is enabled