linux-kernel - Re: [RFC][PATCH] module: Propagate MODULE_STATE

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Message-ID: <20190619113508.GP3463@hirez.programming.kicks-ass.net>
Date:   Wed, 19 Jun 2019 13:35:08 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Miroslav Benes <mbenes@...e.cz>
Cc:     Jessica Yu <jeyu@...nel.org>, linux-kernel@...r.kernel.org,
        jpoimboe@...hat.com, jikos@...nel.org, pmladek@...e.com,
        rostedt@...dmis.org, ast@...nel.org, daniel@...earbox.net
Subject: Re: [RFC][PATCH] module: Propagate MODULE_STATE_COMING notifier
 errors

On Wed, Jun 19, 2019 at 01:33:24PM +0200, Peter Zijlstra wrote:
> How's something like so:
> 
> diff --git a/kernel/module.c b/kernel/module.c
> index 80c7c09584cf..eba6560c89da 100644
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -3631,16 +3631,28 @@ static int complete_formation(struct module *mod, struct load_info *info)
>  
>  static int prepare_coming_module(struct module *mod)
>  {
> -	int err;
> +	struct blocking_notifier_head *nh = &module_notify_list;
> +	int err, nr;
>  
>  	ftrace_module_enable(mod);
>  	err = klp_module_coming(mod);
>  	if (err)
>  		return err;
>  
> -	blocking_notifier_call_chain(&module_notify_list,
> -				     MODULE_STATE_COMING, mod);
> -	return 0;
> +	if (!rcu_access_pointer(nh->head))
> +		return 0;
> +
> +	down_read(&nh->rwsem);
> +	ret = notifier_call_chain(&nh->head, MODULE_STATE_COMING, mod, -1, &nr);
> +	if (ret & NOTIFIER_STOP_MASK)

It compiles _lots_ better with s/ret/err/ on.

> +		notifier_call_chain(&nh->head, MODULE_STATE_GOING, mod, nr, NULL);
> +	up_read(&nh->rwsem);
> +
> +	err = notifier_to_err(err);
> +	if (err)
> +		klp_module_going(mod);
> +
> +	return err;
>  }
>  
>  static int unknown_module_param_cb(char *param, char *val, const char *modname,