Subject: [PATCHv2 02/16] iommu/omap: omap_iommu_attach() should return ENODEV, not NULL

From: [email-masked] (Suman Anna)
Date: Tue, 25 Feb 2014 16:32:03 -0600

Hi Laurent,

On 02/25/2014 03:13 PM, Laurent Pinchart wrote:
> Hi Suman,
>
> Thank you for the patch.
>
> On Thursday 13 February 2014 12:15:33 Suman Anna wrote:
>> From: Florian Vaussard <[email-masked]>
>>
>> omap_iommu_attach() returns NULL or ERR_PTR in case of error, but
>> omap_iommu_attach_dev() only checks for IS_ERR. Thus a NULL return value (in
>> case driver_find_device fails) will cause the kernel to panic when
>> omap_iommu_attach_dev() dereferences the pointer.
>>
>> In such case, omap_iommu_attach() should return ENODEV, not NULL.
>>
>> Signed-off-by: Florian Vaussard <[email-masked]>
>> Acked-by: Suman Anna <[email-masked]>
>> ---
>>   drivers/iommu/omap-iommu.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/iommu/omap-iommu.c b/drivers/iommu/omap-iommu.c
>> index fff2ffd..6272c36 100644
>> --- a/drivers/iommu/omap-iommu.c
>> +++ b/drivers/iommu/omap-iommu.c
>> @@ -863,7 +863,7 @@ static int device_match_by_alias(struct device *dev,
>> void *data) **/
>>   static struct omap_iommu *omap_iommu_attach(const char *name, u32 *iopgd)
>>   {
>> -	int err = -ENOMEM;
>> +	int err = -ENODEV;
>>   	struct device *dev;
>>   	struct omap_iommu *obj;
>>
>> @@ -871,7 +871,7 @@ static struct omap_iommu *omap_iommu_attach(const char
>> *name, u32 *iopgd) (void *)name,
>>   				device_match_by_alias);
>>   	if (!dev)
>> -		return NULL;
>> +		return ERR_PTR(err);
>
> I would return ERR_PTR(-ENODEV) here, and remove the initialization at
> declaration of err above.

The initialization at the beginning is also serving one another exit 
path (a check for try_module_get), where err is not being set. If the 
initialization is removed, then the err has to be set explicitly at the 
other place. Let me know if you still want this changed.

regards
Suman

>>   	obj = to_iommu(dev);