Re: [PATCH v4 1/3] tracing: eprobe: remove duplicate is_good_name() operation

[Linyu Yuan]

hi Tom,

On 6/21/2022 2:38 AM, Tom Zanussi wrote:
> Hi Linyu,
>
> On Tue, 2022-06-14 at 08:48 +0800, Linyu Yuan wrote:
> > hi Tom,
> >
> > On 6/14/2022 5:01 AM, Tom Zanussi wrote:
> > > Hi Linhu,
> > >
> > > On Thu, 2022-06-02 at 20:10 +0800, Linyu Yuan wrote:
> > > > traceprobe_parse_event_name() already validate group and event
> > > > name,
> > > > there is no need to call is_good_name() after it.
> > > >
> > > > Signed-off-by: Linyu Yuan <quic_linyyuan@xxxxxxxxxxx>
> > > > ---
> > > > v2: drop v1 change as it is NACK.
> > > >       add it to remove duplicate is_good_name().
> > > > v3: move it as first patch.
> > > > v4: no change
> > > >
> > > >    kernel/trace/trace_eprobe.c | 4 ----
> > > >    1 file changed, 4 deletions(-)
> > > >
> > > > diff --git a/kernel/trace/trace_eprobe.c
> > > > b/kernel/trace/trace_eprobe.c
> > > > index 7d44785..17d64e3 100644
> > > > --- a/kernel/trace/trace_eprobe.c
> > > > +++ b/kernel/trace/trace_eprobe.c
> > > > @@ -878,16 +878,12 @@ static int __trace_eprobe_create(int argc,
> > > > const char *argv[])
> > > >                   sanitize_event_name(buf1);
> > > >                   event = buf1;
> > > >           }
> > > > -       if (!is_good_name(event) || !is_good_name(group))
> > > > -               goto parse_error;
> > > traceprobe_parse_event_name() is only called if (event).  In the
> > > !event case, wouldn't the is_good_name() checks still be needed
> > > (since
> > > in that case buf1 is assigned to event)?
> > when user input no  event name, it will generate event name from
> > second
> > SYSTEM.EVENT,
> >
> > and it will validate with following traceprobe_parse_event_name().
> Right, but that happens in your second patch '[PATCH v5 2/3] tracing:
> auto generate event name when create a group of events', not this one.
>   
> So if you apply only this patch, the !event case will assign event but
> it will remain unchecked when used later in this function.
>
> It would make more sense to remove this check in patch 2/3 along with
> the code that does the generating...
thanks, will do like this.
> > (
> >
> > if you agree, i will send a new version to update a minor issue in
> > second patch,
> >
> >
> >           sys_event = argv[1];
> > -       ret = traceprobe_parse_event_name(&sys_event, &sys_name,
> > buf2,
> > -                                         sys_event - argv[1]);
> > -       if (ret || !sys_name)
> > +       ret = traceprobe_parse_event_name(&sys_event, &sys_name,
> > buf2, 0);
> > +       if (!sys_event || !sys_name)
> >                   goto parse_error;
> >
> > )
> >
> > > >    
> > > >           sys_event = argv[1];
> > > >           ret = traceprobe_parse_event_name(&sys_event, &sys_name,
> > > > buf2,
> > > >                                             sys_event - argv[1]);
> > > >           if (ret || !sys_name)
> > > >                   goto parse_error;
> > > > -       if (!is_good_name(sys_event) || !is_good_name(sys_name))
> > > > -               goto parse_error;
> > > I agree this one isn't needed.
> But keep this one in this patch, since it's useful on its own as a
> standalone cleanup regardless of whether or not patch 2/3 gets merged.
>
> Tom
>
> > > Thanks,
> > >
> > > Tom
> > >
> > > >    
> > > >           mutex_lock(&event_mutex);
> > > >           event_call = find_and_get_event(sys_name, sys_event);