linux-kernel - Re: [PATCH v4] livepatch/module: Correctly handle coming and going modules

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Message-ID: <alpine.LNX.2.00.1503162011530.25438@pobox.suse.cz>
Date:	Mon, 16 Mar 2015 20:15:43 +0100 (CET)
From:	Jiri Kosina <jkosina@...e.cz>
To:	Petr Mladek <pmladek@...e.cz>,
	Rusty Russell <rusty@...tcorp.com.au>
cc:	Seth Jennings <sjenning@...hat.com>,
	Josh Poimboeuf <jpoimboe@...hat.com>,
	Miroslav Benes <mbenes@...e.cz>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	mingo@...nel.org, mathieu.desnoyers@...icios.com, oleg@...hat.com,
	paulmck@...ux.vnet.ibm.com, live-patching@...r.kernel.org,
	linux-kernel@...r.kernel.org, andi@...stfloor.org,
	rostedt@...dmis.org, Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH v4] livepatch/module: Correctly handle coming and going
 modules

On Thu, 12 Mar 2015, Petr Mladek wrote:

> There is a notifier that handles live patches for coming and going modules.
> It takes klp_mutex lock to avoid races with coming and going patches but
> it does not keep the lock all the time. Therefore the following races are
> possible:
[ ... snip ... ]
> diff --git a/include/linux/module.h b/include/linux/module.h
> index b653d7c0a05a..7232fde6a991 100644
> --- a/include/linux/module.h
> +++ b/include/linux/module.h
> @@ -344,6 +344,10 @@ struct module {
>  	unsigned long *ftrace_callsites;
>  #endif
>  
> +#ifdef CONFIG_LIVEPATCH
> +	bool klp_alive;
> +#endif
> +

Rusty, are you okay with this please? I'd like to have the race fixed in 
4.0 still, but don't want to be making changes to struct module without 
your ack.

Thanks,

-- 
Jiri Kosina
SUSE Labs
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