linux-kernel - Re: [PATCH] block2mtd lockdep_init

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Message-ID: <20080107102025.GA5338@lazybastard.org>
Date:	Mon, 7 Jan 2008 11:20:27 +0100
From:	Jörn Engel <joern@...fs.org>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Erez Zadok <ezk@...sunysb.edu>,
	Jörn Engel <joern@...fs.org>,
	dwmw2@...radead.org, linux-mtd@...ts.infradead.org,
	mingo@...hat.com, linux-kernel@...r.kernel.org,
	Rusty Russell <rusty@...tcorp.com.au>
Subject: Re: [PATCH] block2mtd lockdep_init_map warning

On Mon, 7 January 2008 11:05:26 +0100, Peter Zijlstra wrote:
> 
> Would something like this work for people?

Looks a lot better than what I thought of.  However, does the #ifdef
within is_module_address() make sense when afaict lockdep is the only
caller of that function?  Looks as if the whole function should be made
conditional or none of it.

> Not-Yet-Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
> ---
> Index: linux-2.6/include/linux/sched.h
> ===================================================================
> --- linux-2.6.orig/include/linux/sched.h
> +++ linux-2.6/include/linux/sched.h
> @@ -1160,6 +1160,7 @@ struct task_struct {
>  	int lockdep_depth;
>  	struct held_lock held_locks[MAX_LOCK_DEPTH];
>  	unsigned int lockdep_recursion;
> +	struct module *loading_module;
>  #endif
>  
>  /* journalling filesystem info */
> Index: linux-2.6/kernel/module.c
> ===================================================================
> --- linux-2.6.orig/kernel/module.c
> +++ linux-2.6/kernel/module.c
> @@ -2023,6 +2023,9 @@ static struct module *load_module(void _
>  		printk(KERN_WARNING "%s: Ignoring obsolete parameters\n",
>  		       mod->name);
>  
> +#ifdef CONFIG_LOCKDEP
> +	current->loading_module = mod;
> +#endif
>  	/* Size of section 0 is 0, so this works well if no params */
>  	err = parse_args(mod->name, mod->args,
>  			 (struct kernel_param *)
> @@ -2030,6 +2033,9 @@ static struct module *load_module(void _
>  			 sechdrs[setupindex].sh_size
>  			 / sizeof(struct kernel_param),
>  			 NULL);
> +#ifdef CONFIG_LOCKDEP
> +	current->loading_module = NULL
> +#endif
>  	if (err < 0)
>  		goto arch_cleanup;
>  
> @@ -2454,6 +2460,17 @@ int is_module_address(unsigned long addr
>  		}
>  	}
>  
> +#ifdef CONFIG_LOCKDEP
> +	if (current->loading_module) {
> +		mod = current->loading_module;
> +		if (within(addr, mod->module_init, mod->init_text_size)
> +		    || within(addr, mod->module_core, mod->core_text_size)) {
> +			preempt_enable();
> +			return 1;
> +		}
> +	}
> +#endif
> +
>  	preempt_enable();
>  
>  	return 0;
> 
> 
> 

Jörn

-- 
I don't understand it. Nobody does.
-- Richard P. Feynman
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