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

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Message-ID: <20220816101445.184ebb7c@gandalf.local.home>
Date:   Tue, 16 Aug 2022 10:14:45 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     "Guilherme G. Piccoli" <gpiccoli@...lia.com>
Cc:     akpm@...ux-foundation.org, bhe@...hat.com, pmladek@...e.com,
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        Sergei Shtylyov <sergei.shtylyov@...il.com>
Subject: Re: [PATCH v2 08/13] tracing: Improve panic/die notifiers

On Tue, 19 Jul 2022 16:53:21 -0300
"Guilherme G. Piccoli" <gpiccoli@...lia.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;
}


Thanks,

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

-- Steve