Re: Duplicate fields in event format of `regcache_sync `

[Philippe Duplessis-Guindon]

Sorry Steven I forgot to reply all.
This is the original message:
Perfect,

I can prepare a patch, I think this would be a good learning opportunity 
for me.


Thank you,

Philippe

On 2020-11-20 1:47 p.m., Steven Rostedt wrote:
> On Fri, 20 Nov 2020 12:50:33 -0500
> Philippe Duplessis-Guindon <pduplessis@xxxxxxxxxxxx> wrote:
>
> > Hi,
> >
> > I am doing an ftrace plugin for Babeltrace 2 [1], and while I was
> > parsing the event fields I had an error saying that `regcache_sync` has
> > 2 fields named `type`. The problem seems to come from the
> > drivers/base/regmap/trace.h file [2]. This is the patch where this was
> > added: [3]. The `int field` type is not assigned, so I was wondering if
> > it is normal that the field is there.
> >
> > This is the format of this event:
> >
> > $ sudo cat /sys/kernel/debug/tracing/events/regmap/regcache_sync/format
> > name: regcache_sync
> > ID: 1216
> > format:
> >     field:unsigned short common_type;    offset:0;    size:2;    signed:0;
> >     field:unsigned char common_flags;    offset:2;    size:1;    signed:0;
> >     field:unsigned char common_preempt_count; offset:3; size:1;signed:0;
> >     field:int common_pid;    offset:4;    size:4;    signed:1;
> >
> >     field:__data_loc char[] name;    offset:8;    size:4;    signed:1;
> >     field:__data_loc char[] status;    offset:12;    size:4;    signed:1;
> >     field:__data_loc char[] type;    offset:16;    size:4;    signed:1;
> >     field:int type;    offset:20;    size:4;    signed:1;
> >
> >     print fmt: "%s type=%s status=%s", __get_str(name), __get_str(type),
> > __get_str(status)
>
> It looks like dumb luck that this ever worked. :-/
>
> The correct fix is to nuke that "int type" field. It's not even assigned.
>
> Thanks for pointing this out.
>
> -- Steve
>
>
> > Thank you,
> >
> > Philippe
> >
> >
> > [1] https://babeltrace.org/
> >
> > [2]
> > https://github.com/torvalds/linux/blob/master/drivers/base/regmap/trace.h#L129
> >
> > [3]
> > https://github.com/torvalds/linux/commit/593600890110c02eb471cf844649dee213870416