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

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Message-ID: <20140522084242.GN6679@lee--X1>
Date:	Thu, 22 May 2014 09:42:42 +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

> >> 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.
> 
> But I cannot find any calling code. At least thats what linux cross reference has to say.

Okay, thanks.

I've applied this patch and removed the other.

> Change from V2 -> V3:
> 	Change abx500_dump_all_banks to return int so as to account for error handling.
> 
> Change from V1 -> V2: 
> 	Fix a potential null pointer dereference as reported by kbuild test robot <fengguang.wu@...el.com>.
> 
> From 19d34af7240498b2e624e94b2d003f3d9928dee8 Mon Sep 17 00:00:00 2001
> From: Aurabindo J <mail@...abindo.in>
> Date: Wed, 21 May 2014 22:27:30 +0530
> Subject: [PATCH] mfd: abx500-core: Fix compiler warning larger stack frame
> MIME-Version: 1.0
> Content-Type: text/plain; charset=UTF-8
> Content-Transfer-Encoding: 8bit
> 
> 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. Also change the caller's return type to int so as to
> account for error handling.
> 
> drivers/mfd/abx500-core.c: In function ‘abx500_dump_all_banks’:
> drivers/mfd/abx500-core.c:167:1: warning: the frame size of 1032 bytes
> is larger than 1024 bytes [-Wframe-larger-than=]
> 
> Signed-off-by: Aurabindo J <mail@...abindo.in>
> ---
>  drivers/mfd/abx500-core.c  | 12 ++++++++----
>  include/linux/mfd/abx500.h |  2 +-
>  2 files changed, 9 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/mfd/abx500-core.c b/drivers/mfd/abx500-core.c
> index f3a15aa..d6d0ec4 100644
> --- a/drivers/mfd/abx500-core.c
> +++ b/drivers/mfd/abx500-core.c
> @@ -151,19 +151,23 @@ int abx500_startup_irq_enabled(struct device *dev, unsigned int irq)
>  }
>  EXPORT_SYMBOL(abx500_startup_irq_enabled);
>  
> -void abx500_dump_all_banks(void)
> +int abx500_dump_all_banks(void)
>  {
>  	struct abx500_ops *ops;
> -	struct device dummy_child = {NULL};
> +	struct device *dummy_child;
>  	struct abx500_device_entry *dev_entry;
>  
> +	dummy_child = kzalloc(sizeof(struct device), GFP_KERNEL);
> +	if (!dummy_child)
> +		return -ENOMEM;
>  	list_for_each_entry(dev_entry, &abx500_list, list) {
> -		dummy_child.parent = dev_entry->dev;
> +		dummy_child->parent = dev_entry->dev;
>  		ops = &dev_entry->ops;
>  
>  		if ((ops != NULL) && (ops->dump_all_banks != NULL))
> -			ops->dump_all_banks(&dummy_child);
> +			ops->dump_all_banks(dummy_child);
>  	}
> +	kfree(dummy_child);
>  }
>  EXPORT_SYMBOL(abx500_dump_all_banks);
>  
> diff --git a/include/linux/mfd/abx500.h b/include/linux/mfd/abx500.h
> index 3301b20..df2508f 100644
> --- a/include/linux/mfd/abx500.h
> +++ b/include/linux/mfd/abx500.h
> @@ -330,7 +330,7 @@ int abx500_mask_and_set_register_interruptible(struct device *dev, u8 bank,
>  int abx500_get_chip_id(struct device *dev);
>  int abx500_event_registers_startup_state_get(struct device *dev, u8 *event);
>  int abx500_startup_irq_enabled(struct device *dev, unsigned int irq);
> -void abx500_dump_all_banks(void);
> +int abx500_dump_all_banks(void);
>  
>  struct abx500_ops {
>  	int (*get_chip_id) (struct device *);



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