linux-kernel - Re: [PATCH v4 3/3] kexec: Introduce sysctl parameters kexec_load_limit

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Date:   Wed, 21 Dec 2022 09:14:35 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Ricardo Ribalda <ribalda@...omium.org>
Cc:     Jonathan Corbet <corbet@....net>, Philipp Rudo <prudo@...hat.com>,
        Eric Biederman <ebiederm@...ssion.com>,
        "Guilherme G. Piccoli" <gpiccoli@...lia.com>,
        kexec@...ts.infradead.org, Ross Zwisler <zwisler@...nel.org>,
        "Joel Fernandes (Google)" <joel@...lfernandes.org>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org
Subject: Re: [PATCH v4 3/3] kexec: Introduce sysctl parameters
 kexec_load_limit_*

On Wed, 21 Dec 2022 13:50:03 +0100
Ricardo Ribalda <ribalda@...omium.org> wrote:

> @@ -941,6 +995,20 @@ static struct ctl_table kexec_core_sysctls[] = {
>  		.extra1		= SYSCTL_ONE,
>  		.extra2		= SYSCTL_ONE,
>  	},
> +	{
> +		.procname	= "kexec_load_limit_panic",
> +		.data		= &load_limit_panic,
> +		.maxlen		= sizeof(load_limit_panic),

If I understand the sysctl logic correctly, the .maxlen is the maxlen of
the input to the sysctl, and not the data. Usually set to sizeof(data)
because most proc_handlers write to data directly.

In this case, I believe it's not even used (you override it with the
struct ctl_table tmp). I guess it doesn't really matter what it's set to.
Perhaps just set it to zero and leave it out?

> +		.mode		= 0644,
> +		.proc_handler	= kexec_limit_handler,
> +	},
> +	{
> +		.procname	= "kexec_load_limit_reboot",
> +		.data		= &load_limit_reboot,
> +		.maxlen		= sizeof(load_limit_reboot),

Same here.

-- Steve

> +		.mode		= 0644,
> +		.proc_handler	= kexec_limit_handler,
> +	},
>  	{ }
>  };
>