On Fri, Jan 30, 2015 at 10:25:37AM -0500, Steven Rostedt wrote:
> On Mon, Jan 26, 2015 at 06:38:24PM +0800, Wang Nan wrote:
> > (If Steven Rostedt accept the previous patch which introduce a priv
> > field to 'struct format_field', we can use a relative simple method
> > for name conversion. If not , perf must track name conversion by
> > itself.)
>
> Sorry for coming in so late here.
>
> >
> > Some parameters of syscall tracepoints named as 'nr', 'event', etc.
> > When dealing with them, perf convert to ctf meets some problem:
> >
> > 1. If a parameter with name 'nr', it will duplicate syscall's
> > common field 'nr'. One such syscall is io_submit().
> >
> > 2. If a parameter with name 'event', it is denied to be inserted
> > because 'event' is a babeltrace keywork. One such syscall is
> > epoll_ctl.
> >
> > This patch appends '_dupl_X' suffix to avoid problem 1, prepend a '_'
> > prefix to avoid problem 2.
>
> Actually, I don't like this approach. That is, to have this private
> data structure. Why not just add an "alias" to format_field. In other
> words, instead of hiding this interaction behind a void pointer and
> needing to create a function pointer to free it, just add another
> field to format field and be done with it. I think it would make
> the code a hell of a lot simpler and easier to understand.
>
> struct format_field {
> struct format_field *next;
> struct event_format *event;
> char *type;
> char *name;
> + char *alias;
> int offset;
> int size;
> unsigned int arraylen;
> unsigned int elementsize;
> unsigned long flags;
> };
>
> And put the logic in event parse to free alias if need be.
> Heck, you could even add a pevent_*() func to assign the alias
> using strdup, or what not.
ok, sounds good
thanks,
jirka
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