[PATCH 01/90] staging: comedi: comedidev.h: introduce comedi_to_pci_dev() helper

[PATCH 01/90] staging: comedi: comedidev.h: introduce comedi_to_pci_dev() helper

[H Hartley Sweeten]

Introduce a wrapper for to_pci_dev() to allow the comedi pci drivers
to store the pci_dev pointer in the comedi_device hw_dev variable and
retrieve it easily.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/staging/comedi/comedidev.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/staging/comedi/comedidev.h b/drivers/staging/comedi/comedidev.h
index de8c99c..620222d 100644
--- a/drivers/staging/comedi/comedidev.h
+++ b/drivers/staging/comedi/comedidev.h
@@ -446,6 +446,11 @@ static inline void comedi_set_hw_dev(struct comedi_device *dev,
 	}
 }
 
+static inline struct pci_dev *comedi_to_pci_dev(struct comedi_device *dev)
+{
+	return to_pci_dev(dev->hw_dev);
+}
+
 int comedi_buf_put(struct comedi_async *async, short x);
 int comedi_buf_get(struct comedi_async *async, short *x);
 
-- 
1.7.11

Re: [PATCH 01/90] staging: comedi: comedidev.h: introduce comedi_to_pci_dev() helper

[Ian Abbott]

On 2012-07-19 02:24, H Hartley Sweeten wrote:
> Introduce a wrapper for to_pci_dev() to allow the comedi pci drivers
> to store the pci_dev pointer in the comedi_device hw_dev variable and
> retrieve it easily.
>
> Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
> Cc: Ian Abbott <abbotti@mev.co.uk>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
>   drivers/staging/comedi/comedidev.h | 5 +++++
>   1 file changed, 5 insertions(+)
>
> diff --git a/drivers/staging/comedi/comedidev.h b/drivers/staging/comedi/comedidev.h
> index de8c99c..620222d 100644
> --- a/drivers/staging/comedi/comedidev.h
> +++ b/drivers/staging/comedi/comedidev.h
> @@ -446,6 +446,11 @@ static inline void comedi_set_hw_dev(struct comedi_device *dev,
>   	}
>   }
>
> +static inline struct pci_dev *comedi_to_pci_dev(struct comedi_device *dev)
> +{
> +	return to_pci_dev(dev->hw_dev);
> +}
> +

That needs to be something like:

	return dev->hw_dev ? to_pci_dev(dev->hw_dev) : NULL;

-- 
-=( Ian Abbott @ MEV Ltd.    E-mail: <abbotti@mev.co.uk>        )=-
-=( Tel: +44 (0)161 477 1898   FAX: +44 (0)161 718 3587         )=-

RE: [PATCH 01/90] staging: comedi: comedidev.h: introduce comedi_to_pci_dev() helper

[H Hartley Sweeten]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain; charset="utf-8", Size: 1539 bytes --]

On Thursday, July 19, 2012 2:23 AM, Ian Abbott wrote:
> On 2012-07-19 02:24, H Hartley Sweeten wrote:
>> Introduce a wrapper for to_pci_dev() to allow the comedi pci drivers
>> to store the pci_dev pointer in the comedi_device hw_dev variable and
>> retrieve it easily.
>>
>> Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
>> Cc: Ian Abbott <abbotti@mev.co.uk>
>> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>> ---
>>   drivers/staging/comedi/comedidev.h | 5 +++++
>>   1 file changed, 5 insertions(+)
>>
>> diff --git a/drivers/staging/comedi/comedidev.h b/drivers/staging/comedi/comedidev.h
>> index de8c99c..620222d 100644
>> --- a/drivers/staging/comedi/comedidev.h
>> +++ b/drivers/staging/comedi/comedidev.h
>> @@ -446,6 +446,11 @@ static inline void comedi_set_hw_dev(struct comedi_device *dev,
>>   	}
>>   }
>>
>> +static inline struct pci_dev *comedi_to_pci_dev(struct comedi_device *dev)
>> +{
>> +	return to_pci_dev(dev->hw_dev);
>> +}
>> +
>
> That needs to be something like:
>
>	return dev->hw_dev ? to_pci_dev(dev->hw_dev) : NULL;

Hmm.. I'm not really sure.

I assumed that the container_of() macro would return NULL if the ptr passed to
it was NULL. But, I'm not sure how this actually unwinds for that case.

Greg, do you know if the NULL check is needed? It's is possible that the dev->hw_dev
pointer could be NULL.

Thanks,
Hartley

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Re: [PATCH 01/90] staging: comedi: comedidev.h: introduce comedi_to_pci_dev() helper

[Dan Carpenter]

On Thu, Jul 19, 2012 at 11:20:52AM -0500, H Hartley Sweeten wrote:
> On Thursday, July 19, 2012 2:23 AM, Ian Abbott wrote:
> > On 2012-07-19 02:24, H Hartley Sweeten wrote:
> >> Introduce a wrapper for to_pci_dev() to allow the comedi pci drivers
> >> to store the pci_dev pointer in the comedi_device hw_dev variable and
> >> retrieve it easily.
> >>
> >> Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
> >> Cc: Ian Abbott <abbotti@mev.co.uk>
> >> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> >> ---
> >>   drivers/staging/comedi/comedidev.h | 5 +++++
> >>   1 file changed, 5 insertions(+)
> >>
> >> diff --git a/drivers/staging/comedi/comedidev.h b/drivers/staging/comedi/comedidev.h
> >> index de8c99c..620222d 100644
> >> --- a/drivers/staging/comedi/comedidev.h
> >> +++ b/drivers/staging/comedi/comedidev.h
> >> @@ -446,6 +446,11 @@ static inline void comedi_set_hw_dev(struct comedi_device *dev,
> >>   	}
> >>   }
> >>
> >> +static inline struct pci_dev *comedi_to_pci_dev(struct comedi_device *dev)
> >> +{
> >> +	return to_pci_dev(dev->hw_dev);
> >> +}
> >> +
> >
> > That needs to be something like:
> >
> >	return dev->hw_dev ? to_pci_dev(dev->hw_dev) : NULL;
> 
> Hmm.. I'm not really sure.
> 
> I assumed that the container_of() macro would return NULL if the ptr passed to
> it was NULL. But, I'm not sure how this actually unwinds for that case.
> 
> Greg, do you know if the NULL check is needed? It's is possible that the dev->hw_dev
> pointer could be NULL.
> 

container_of() just does pointer math with the offset.  Since
->hw_dev is not the first member of the pci_dev struct then
to_pci_dev() never returns NULL.  If you give it a NULL pointer it
returns a bogus pointer back.

regards,
dan carpenter

RE: [PATCH 01/90] staging: comedi: comedidev.h: introduce comedi_to_pci_dev() helper

[H Hartley Sweeten]

On Thursday, July 19, 2012 9:32 AM, Dan Carpenter wrote:
> On Thu, Jul 19, 2012 at 11:20:52AM -0500, H Hartley Sweeten wrote:
>> On Thursday, July 19, 2012 2:23 AM, Ian Abbott wrote:
>>> That needs to be something like:
>>>
>>>	return dev->hw_dev ? to_pci_dev(dev->hw_dev) : NULL;
>> 
>> Hmm.. I'm not really sure.
>> 
>> I assumed that the container_of() macro would return NULL if the ptr passed to
>> it was NULL. But, I'm not sure how this actually unwinds for that case.
>> 
>> Greg, do you know if the NULL check is needed? It's is possible that the dev->hw_dev
>> pointer could be NULL.
>> 
>
> container_of() just does pointer math with the offset.  Since
> ->hw_dev is not the first member of the pci_dev struct then
> to_pci_dev() never returns NULL.  If you give it a NULL pointer it
> returns a bogus pointer back.

Thanks for the information.

I'll update PATCH 01/90 and repost it as v2.

Thanks,
Hartley