Re: [PATCH v4 12/22] iommu: introduce device fault report API

[Jacob Pan]

On Mon, 30 Apr 2018 17:53:52 +0100
Jean-Philippe Brucker <jean-philippe.bruc...@arm.com> wrote:

> Hi,
> 
> I noticed a couple issues when testing
> 
> On 16/04/18 22:49, Jacob Pan wrote:
> > +int iommu_register_device_fault_handler(struct device *dev,
> > +                                   iommu_dev_fault_handler_t
> > handler,
> > +                                   void *data)
> > +{
> > +   struct iommu_param *param = dev->iommu_param;
> > +
> > +   /*
> > +    * Device iommu_param should have been allocated when
> > device is
> > +    * added to its iommu_group.
> > +    */
> > +   if (!param)
> > +           return -EINVAL;
> > +
> > +   /* Only allow one fault handler registered for each device
> > */
> > +   if (param->fault_param)
> > +           return -EBUSY;  
> 
> Should this be inside the param lock? We probably don't expect
> concurrent register/unregister but it seems cleaner
agreed, same as corrections below. Thanks!
> 
>  [...]  
> 
> We should return EINVAL here, if fault_param is NULL. That way users
> can call unregister_fault_handler unconditionally in their cleanup
> paths
> 
> > +   /* we cannot unregister handler if there are pending
> > faults */
> > +   if (list_empty(&param->fault_param->faults)) {  
> 
> if (!list_empty(...))
> 
> > +           ret = -EBUSY;
> > +           goto unlock;
> > +   }
> > +
> > +   list_del(&param->fault_param->faults);  
> 
> faults is the list head, no need for list_del
> 
> > +   kfree(param->fault_param);
> > +   param->fault_param = NULL;
> > +   put_device(dev);
> > +
> > +unlock:
> > +   mutex_unlock(&param->lock);
> > +
> > +   return 0;  
> 
> return ret
> 
> Thanks,
> Jean

[Jacob Pan]
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