linux-kernel - Re: [PATCH v2 vfio 0/3] pds/vfio: Fixes for locking bugs

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Date:   Fri, 13 Oct 2023 15:09:40 -0600
From:   Alex Williamson <alex.williamson@...hat.com>
To:     Brett Creeley <brett.creeley@....com>
Cc:     <jgg@...pe.ca>, <yishaih@...dia.com>,
        <shameerali.kolothum.thodi@...wei.com>, <kevin.tian@...el.com>,
        <dan.carpenter@...aro.org>, <kvm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <shannon.nelson@....com>
Subject: Re: [PATCH v2 vfio 0/3] pds/vfio: Fixes for locking bugs

On Wed, 11 Oct 2023 16:01:12 -0700
Brett Creeley <brett.creeley@....com> wrote:

> This series contains fixes for locking bugs in the recently introduced
> pds-vfio-pci driver. There was an initial bug reported by Dan Carpenter
> at:
> 
> https://lore.kernel.org/kvm/1f9bc27b-3de9-4891-9687-ba2820c1b390@moroto.mountain/
> 
> However, more locking bugs were found when looking into the previously
> mentioned issue. So, all fixes are included in this series.
> 
> v2:
> https://lore.kernel.org/kvm/20230914191540.54946-1-brett.creeley@amd.com/
> - Trim the OOPs in the patch commit messages
> - Rework patch 3/3 to only unlock the spinlock once

I thought we determined the spinlock, and thus the atomic context, was
an arbitrary choice.  I would have figured we simply convert it to a
mutex.  Why didn't we take that route?  Thanks,

Alex

> - Destroy the state_mutex in the driver specific vfio_device_ops.release
>   callback
> 
> Brett Creeley (3):
>   pds/vfio: Fix spinlock bad magic BUG
>   pds/vfio: Fix mutex lock->magic != lock warning
>   pds/vfio: Fix possible sleep while in atomic context
> 
>  drivers/vfio/pci/pds/vfio_dev.c | 27 ++++++++++++++++++++-------
>  1 file changed, 20 insertions(+), 7 deletions(-)
>