Re: [PATCH v3 10/16] iommu: introduce device fault report API

[Jacob Pan]

On Fri, 8 Dec 2017 13:59:09 -0700
Alex Williamson <alex.williamson@xxxxxxxxxx> wrote:

> > > 
> > > Isn't this all rather racy?  I see that we can have multiple
> > > callers to register racing.    
> > I agree, should use a lock here to prevent unregister. For multiple
> > caller race, it won't happen since there is only one caller can
> > register handler.  
> 
> If you have multiple simultaneous callers to
> iommu_register_device_fault_handler, they can all get past the test
> for fault_param (testing and setting is not atomic), then it's
> indeterminate which handler gets installed.  Thanks,
> 
I see, having the mutex would prevent it. Later callers would get
-EBUSY.
Thanks a lot!
> Alex