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* Re: [PATCH v2] NFC: pn544_hci: move the dereference below the NULL test
@ 2012-09-08  3:34 Wei Yongjun
  2012-09-08 12:37 ` Larry Finger
  2012-09-10 13:10 ` Kalle Valo
  0 siblings, 2 replies; 5+ messages in thread
From: Wei Yongjun @ 2012-09-08  3:34 UTC (permalink / raw)
  To: Larry.Finger
  Cc: lauro.venancio, aloisio.almeida, sameo, yongjun_wei, linux-wireless

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)




^ permalink raw reply related	[flat|nested] 5+ messages in thread
* Re: [PATCH v2] NFC: pn544_hci: move the dereference below the NULL test
  2012-09-08  3:34 [PATCH v2] NFC: pn544_hci: move the dereference below the NULL test Wei Yongjun
@ 2012-09-08 12:37 ` Larry Finger
  2012-09-10 13:10 ` Kalle Valo
  1 sibling, 0 replies; 5+ messages in thread
From: Larry Finger @ 2012-09-08 12:37 UTC (permalink / raw)
  To: Wei Yongjun
  Cc: lauro.venancio, aloisio.almeida, sameo, yongjun_wei, linux-wireless

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



^ permalink raw reply	[flat|nested] 5+ messages in thread
* Re: [PATCH v2] NFC: pn544_hci: move the dereference below the NULL test
  2012-09-08  3:34 [PATCH v2] NFC: pn544_hci: move the dereference below the NULL test Wei Yongjun
  2012-09-08 12:37 ` Larry Finger
@ 2012-09-10 13:10 ` Kalle Valo
  1 sibling, 0 replies; 5+ messages in thread
From: Kalle Valo @ 2012-09-10 13:10 UTC (permalink / raw)
  To: Wei Yongjun
  Cc: Larry.Finger, lauro.venancio, aloisio.almeida, sameo,
	yongjun_wei, linux-wireless

Wei Yongjun <weiyj.lk@gmail.com> writes:

> -	BUG_ON(!info);
> -	BUG_ON(irq != info->i2c_dev->irq);
> +	if (!info || irq != info->i2c_dev->irq) {
> +		WARN_ON_ONCE(1);
> +		return IRQ_NONE;
> +	}

You can even simplify it to this:

if (WARN_ON_ONCE(!info || irq != info->i2c_dev->irq))
	return IRQ_NONE;

I don't know if it matters here but if it's important to know which test
is failing having two different tests makes that easier, as the line
number will be different:

if (WARN_ON_ONCE(!info))
	return IRQ_NONE;

if (WARN_ON_ONCE(irq != info->i2c_dev->irq))
	return IRQ_NONE;

-- 
Kalle Valo

^ permalink raw reply	[flat|nested] 5+ messages in thread
* Re: [PATCH v2] NFC: pn544_hci: move the dereference below the NULL test
  2012-09-08  1:53 Wei Yongjun
@ 2012-09-08  2:03 ` Larry Finger
  0 siblings, 0 replies; 5+ messages in thread
From: Larry Finger @ 2012-09-08  2:03 UTC (permalink / raw)
  To: Wei Yongjun
  Cc: lauro.venancio, aloisio.almeida, sameo, yongjun_wei, linux-wireless

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>
> ---
>   drivers/nfc/pn544_hci.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/nfc/pn544_hci.c b/drivers/nfc/pn544_hci.c
> index aa71807..7b20f2d 100644
> --- a/drivers/nfc/pn544_hci.c
> +++ b/drivers/nfc/pn544_hci.c
> @@ -341,13 +341,14 @@ 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);
>
> +	client = info->i2c_dev;

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.

Larry

>   	dev_dbg(&client->dev, "IRQ\n");
>
>   	if (info->hard_fault != 0)
>
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-wireless" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>


^ permalink raw reply	[flat|nested] 5+ messages in thread
* [PATCH v2] NFC: pn544_hci: move the dereference below the NULL test
@ 2012-09-08  1:53 Wei Yongjun
  2012-09-08  2:03 ` Larry Finger
  0 siblings, 1 reply; 5+ messages in thread
From: Wei Yongjun @ 2012-09-08  1:53 UTC (permalink / raw)
  To: lauro.venancio, aloisio.almeida, sameo; +Cc: yongjun_wei, linux-wireless

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>
---
 drivers/nfc/pn544_hci.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/nfc/pn544_hci.c b/drivers/nfc/pn544_hci.c
index aa71807..7b20f2d 100644
--- a/drivers/nfc/pn544_hci.c
+++ b/drivers/nfc/pn544_hci.c
@@ -341,13 +341,14 @@ 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);
 
+	client = info->i2c_dev;
 	dev_dbg(&client->dev, "IRQ\n");
 
 	if (info->hard_fault != 0)



^ permalink raw reply related	[flat|nested] 5+ messages in thread
end of thread, other threads:[~2012-09-10 13:10 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2012-09-08  3:34 [PATCH v2] NFC: pn544_hci: move the dereference below the NULL test Wei Yongjun
2012-09-08 12:37 ` Larry Finger
2012-09-10 13:10 ` Kalle Valo
  -- strict thread matches above, loose matches on Subject: below --
2012-09-08  1:53 Wei Yongjun
2012-09-08  2:03 ` Larry Finger

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