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Date:   Fri, 13 Jan 2023 10:50:29 -0400
From:   Jason Gunthorpe <jgg@nvidia.com>
To:     Matthew Rosato <mjrosato@linux.ibm.com>
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Subject: Re: [PATCH v2] vfio: fix potential deadlock on vfio group lock
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On Thu, Jan 12, 2023 at 04:51:36PM -0500, Matthew Rosato wrote:

> Yep, thanks.  I will surround this bit of code with
> 
> mutex_lock(&device->dev_set->lock);
> ..
> mutex_unlock(&device->dev_set->lock);

Don't do it like that, copy the kvm out of the struct device to the
stack and NULL it. Then do the put without holding any locks.

Jason