Re: [PATCH v2 08/13] tracing: Improve panic/die notifiers

Alan Stern
2022-08-16T14:57:25Z

On Tue, Aug 16, 2022 at 10:14:45AM -0400, Steven Rostedt wrote:
> On Tue, 19 Jul 2022 16:53:21 -0300
> "Guilherme G. Piccoli" <gpiccoli@igalia.com> wrote:
>
>
> Sorry for the late review, but this fell to the bottom of my queue :-/
>
> > +/*
> > + * The idea is to execute the following die/panic callback early, in order
> > + * to avoid showing irrelevant information in the trace (like other panic
> > + * notifier functions); we are the 2nd to run, after hung_task/rcu_stall
> > + * warnings get disabled (to prevent potential log flooding).
> > + */
> > +static int trace_die_panic_handler(struct notifier_block *self,
> > + unsigned long ev, void *unused)
> > +{
> > + if (!ftrace_dump_on_oops)
> > + goto out;
> > +
> > + if (self == &trace_die_notifier && ev != DIE_OOPS)
> > + goto out;
>
> I really hate gotos that are not for clean ups.
>
> > +
> > + ftrace_dump(ftrace_dump_on_oops);
> > +
> > +out:
> > + return NOTIFY_DONE;
> > +}
> > +
>
> Just do:
>
> static int trace_die_panic_handler(struct notifier_block *self,
> unsigned long ev, void *unused)
> {
> if (!ftrace_dump_on_oops)
> return NOTIFY_DONE;
>
> /* The die notifier requires DIE_OOPS to trigger */
> if (self == &trace_die_notifier && ev != DIE_OOPS)
> return NOTIFY_DONE;
>
> ftrace_dump(ftrace_dump_on_oops);
>
> return NOTIFY_DONE;
> }

Or better yet:

if (ftrace_dump_on_oops) {

/* The die notifier requires DIE_OOPS to trigger */
if (self != &trace_die_notifier || ev == DIE_OOPS)
ftrace_dump(ftrace_dump_on_oops);
}
return NOTIFY_DONE;

Alan Stern

> Thanks,
>
> Other than that, Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
>
> -- Steve