Linux Virtualization - Feb 2017 - [PATCH 2/9] virtio_pci: use shared interrupts for virtqueues

On 2017?01?27? 16:16, Christoph Hellwig wrote:
> +		snprintf(vp_dev->msix_names[i + 1],
> +			 sizeof(*vp_dev->msix_names), "%s-%s",
>   			 dev_name(&vp_dev->vdev.dev), names[i]);
>   		err = request_irq(pci_irq_vector(vp_dev->pci_dev, msix_vec),
> -				  vring_interrupt, 0,
> -				  vp_dev->msix_names[msix_vec],
> -				  vqs[i]);
> +				  vring_interrupt, IRQF_SHARED,
> +				  vp_dev->msix_names[i + 1], vqs[i]);
Do we need to check per_vq_vectors before dereferencing msix_names[i + 1] ?

Thanks

On Fri, Feb 03, 2017 at 03:54:54PM +0800, Jason Wang
wrote:
> On 2017?01?27? 16:16, Christoph Hellwig wrote:
>> +		snprintf(vp_dev->msix_names[i + 1],
>> +			 sizeof(*vp_dev->msix_names), "%s-%s",
>>   			 dev_name(&vp_dev->vdev.dev), names[i]);
>>   		err = request_irq(pci_irq_vector(vp_dev->pci_dev, msix_vec),
>> -				  vring_interrupt, 0,
>> -				  vp_dev->msix_names[msix_vec],
>> -				  vqs[i]);
>> +				  vring_interrupt, IRQF_SHARED,
>> +				  vp_dev->msix_names[i + 1], vqs[i]);
>
> Do we need to check per_vq_vectors before dereferencing msix_names[i + 1] ?
No, we need to allocate the array larger in that case as want proper
names for the interrupts.

On 2017?02?03? 16:26, Christoph Hellwig wrote:
> On Fri, Feb 03, 2017 at 03:54:54PM +0800, Jason Wang wrote:
>> On 2017?01?27? 16:16, Christoph Hellwig wrote:
>>> +		snprintf(vp_dev->msix_names[i + 1],
>>> +			 sizeof(*vp_dev->msix_names), "%s-%s",
>>>    			 dev_name(&vp_dev->vdev.dev), names[i]);
>>>    		err = request_irq(pci_irq_vector(vp_dev->pci_dev,
msix_vec),
>>> -				  vring_interrupt, 0,
>>> -				  vp_dev->msix_names[msix_vec],
>>> -				  vqs[i]);
>>> +				  vring_interrupt, IRQF_SHARED,
>>> +				  vp_dev->msix_names[i + 1], vqs[i]);
>> Do we need to check per_vq_vectors before dereferencing msix_names[i +
1] ?
> No, we need to allocate the array larger in that case as want proper
> names for the interrupts.
Consider the case of !per_vq_vectors, the size of msix_names is 2, but 
snprintf can do out of bound accessing here. (We name the msix shared by 
virtqueues with something like "%s-virtqueues" before the patch).

Thanks