Re: [PATCH v2] NFC: pn544_hci: move the dereference below the NULL test

[Larry Finger <Larry.Finger@lwfinger.net>]

On 09/07/2012 10:34 PM, Wei Yongjun wrote:
> On 09/08/2012 10:03 AM, Larry Finger wrote:
>> On 09/07/2012 08:53 PM, Wei Yongjun wrote:
>>> From: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
>>>
>>> The dereference should be moved below the NULL test.
>>>
>>> spatch with a semantic match is used to found this.
>>> (http://coccinelle.lip6.fr/)
>>>
>>> Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
>>> ---
>>>
>>
>> As long as you are reworking this section, doesn't BUG_ON seem a little harsh? I do not think the kernel should ever be crashed because a non-essential driver is messed up. As the patch would be a totally different change, it should be a new submission, but I think each of these conditions should trigger a WARN_ON_ONCE, and return IRQ_NONE when they occur.
>>
> You means the should be like this?
>
> diff --git a/drivers/nfc/pn544_hci.c b/drivers/nfc/pn544_hci.c
> index aa71807..e42b100 100644
> --- a/drivers/nfc/pn544_hci.c
> +++ b/drivers/nfc/pn544_hci.c
> @@ -341,13 +341,16 @@ flush:
>   static irqreturn_t pn544_hci_irq_thread_fn(int irq, void *dev_id)
>   {
>   	struct pn544_hci_info *info = dev_id;
> -	struct i2c_client *client = info->i2c_dev;
> +	struct i2c_client *client;
>   	struct sk_buff *skb = NULL;
>   	int r;
>
> -	BUG_ON(!info);
> -	BUG_ON(irq != info->i2c_dev->irq);
> +	if (!info || irq != info->i2c_dev->irq) {
> +		WARN_ON_ONCE(1);
> +		return IRQ_NONE;
> +	}
>
> +	client = info->i2c_dev;
>   	dev_dbg(&client->dev, "IRQ\n");
>
>   	if (info->hard_fault != 0)

Yes, that looks better to me.

Larry