linux-kernel - Re: [PATCH V2] mfd: abx500-core: Fix compiler warning larger stack frame

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Message-ID: <20140521091751.GC6679@lee--X1>
Date:	Wed, 21 May 2014 10:17:51 +0100
From:	Lee Jones <lee.jones@...aro.org>
To:	Jay Aurabind <mail@...abindo.in>
Cc:	Linus Walleij <linus.walleij@...aro.org>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	kbuild test robot <fengguang.wu@...el.com>
Subject: Re: [PATCH V2] mfd: abx500-core: Fix compiler warning larger stack
 frame

> Change from V1 -> V2: Fix a potential null pointer dereference as reported by kbuild test robot <fengguang.wu@...el.com>.
> 
> Inorder to report the kzalloc failure, I have just used a pr_debug statement. If it looks ugly, should I change the function's return value to int and give out an -ENOMEM ?

Yes, please do that - and obviously add the checks to the calling code.

> From 6615c7a995a6bb4dcf4c1e9ac59bca823ec821a5 Mon Sep 17 00:00:00 2001
> From: Aurabindo J <mail@...abindo.in>
> Date: Wed, 21 May 2014 11:18:10 +0530
> Subject: [PATCH] mfd: abx500-core: Fix compiler warning larger stack frame
> 
> On systems with CONFIG_FRAME_WARN=1024, compiler warns the allocation of
> an object of struct device on stack. Make the allocation dynamically to
> fix the warning.
> 
> Signed-off-by: Aurabindo J <mail@...abindo.in>
> ---
>  drivers/mfd/abx500-core.c | 19 ++++++++++++-------
>  1 file changed, 12 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/mfd/abx500-core.c b/drivers/mfd/abx500-core.c
> index f3a15aa..5e5098d 100644
> --- a/drivers/mfd/abx500-core.c
> +++ b/drivers/mfd/abx500-core.c
> @@ -154,16 +154,21 @@ EXPORT_SYMBOL(abx500_startup_irq_enabled);
>  void abx500_dump_all_banks(void)
>  {
>  	struct abx500_ops *ops;
> -	struct device dummy_child = {NULL};
> +	struct device *dummy_child;
>  	struct abx500_device_entry *dev_entry;
>  
> -	list_for_each_entry(dev_entry, &abx500_list, list) {
> -		dummy_child.parent = dev_entry->dev;
> -		ops = &dev_entry->ops;
> +	dummy_child = kzalloc(sizeof(struct device), GFP_KERNEL);
> +	if (dummy_child != NULL) {
> +		list_for_each_entry(dev_entry, &abx500_list, list) {
> +			dummy_child->parent = dev_entry->dev;
> +			ops = &dev_entry->ops;
>  
> -		if ((ops != NULL) && (ops->dump_all_banks != NULL))
> -			ops->dump_all_banks(&dummy_child);
> -	}
> +			if ((ops != NULL) && (ops->dump_all_banks != NULL))
> +				ops->dump_all_banks(dummy_child);
> +		}
> +		kfree(dummy_child);
> +	} else
> +		pr_debug("kzalloc failure in abx500_dump_all_banks\n");
>  }
>  EXPORT_SYMBOL(abx500_dump_all_banks);
>  



-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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