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From: Halil Pasic <pasic@linux.ibm.com>
To: Jason Gunthorpe <jgg@nvidia.com>
Cc: Tony Krowiak <akrowiak@linux.ibm.com>,
	linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org,
	borntraeger@de.ibm.com, cohuck@redhat.com,
	pasic@linux.vnet.ibm.com, jjherne@linux.ibm.com,
	alex.williamson@redhat.com, kwankhede@nvidia.com,
	david@redhat.com
Subject: Re: [PATCH 2/2] s390/vfio-ap: replace open coded locks for VFIO_GROUP_NOTIFY_SET_KVM notification
Date: Tue, 27 Jul 2021 00:43:29 +0200	[thread overview]
Message-ID: <20210727004329.3bcc7d4f.pasic@linux.ibm.com> (raw)
In-Reply-To: <20210726220317.GA1721383@nvidia.com>

On Mon, 26 Jul 2021 19:03:17 -0300
Jason Gunthorpe <jgg@nvidia.com> wrote:

> > You may end up with open and close running interleaved. What I'
> > trying to say is, to my best knowledge, normally there is no
> > you have to close it before you open it again rule for files.  
> 
> This is an existing bug in this driver, I've fixed in the reflck series.
> 
> open_device/close_device will not run concurrently, or out of order,
> afer it is fixed.

Well if that is the case then provided your fix precedes this patch:

Acked-by: Halil Pasic <pasic@linux.ibm.com>

I'm not entirely happy with this. I did not thoroughly investigate the
implications of reversing the locking order of the vfio-ap lock (driver
global) and the kvm lock (guest specific). I will trust Tony and hope
our KVM maintainers will scream if this is bad from interference and
delay perspective.

Regards,
Halil

  reply	other threads:[~2021-07-26 22:43 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-19 19:35 [PATCH 0/2] s390/vfio-ap: do not open code locks for VFIO_GROUP_NOTIFY_SET_KVM notification Tony Krowiak
2021-07-19 19:35 ` [PATCH 1/2] s390/vfio-ap: r/w lock for PQAP interception handler function pointer Tony Krowiak
2021-08-18 17:03   ` Christian Borntraeger
2021-08-18 23:25     ` Halil Pasic
2021-08-19  6:56       ` Christian Borntraeger
2021-08-19 13:36       ` Tony Krowiak
2021-08-19 21:42         ` Halil Pasic
2021-08-23 13:08           ` Tony Krowiak
2021-08-19 13:20     ` Tony Krowiak
2021-08-19 17:54       ` Alex Williamson
2021-08-19 17:58         ` Jason Gunthorpe
2021-08-20 15:59           ` Tony Krowiak
2021-08-20 22:05           ` Tony Krowiak
2021-08-20 22:30             ` Jason Gunthorpe
2021-08-23 15:17               ` Tony Krowiak
2021-08-20 22:41             ` Alex Williamson
2021-08-23 20:51               ` Tony Krowiak
2021-07-19 19:35 ` [PATCH 2/2] s390/vfio-ap: replace open coded locks for VFIO_GROUP_NOTIFY_SET_KVM notification Tony Krowiak
2021-07-21 14:45   ` Halil Pasic
2021-07-22 13:09     ` Tony Krowiak
2021-07-23 14:26       ` Halil Pasic
2021-07-23 21:24         ` Tony Krowiak
2021-07-26 20:36           ` Halil Pasic
2021-07-26 22:03             ` Jason Gunthorpe
2021-07-26 22:43               ` Halil Pasic [this message]
2021-07-28 13:43                 ` Tony Krowiak
2021-07-28 19:42                   ` Halil Pasic
2021-07-30 13:33                     ` Tony Krowiak
2021-07-27  6:54               ` Christoph Hellwig
2021-07-21 19:37   ` Jason J. Herne
2021-07-22 13:16     ` Tony Krowiak
2021-08-02 13:10 ` [PATCH 0/2] s390/vfio-ap: do not open code " Tony Krowiak
2021-08-02 13:53   ` Halil Pasic
2021-08-02 16:32     ` Tony Krowiak
2021-08-03 13:08       ` Jason Gunthorpe
2021-08-03 13:34         ` Tony Krowiak
2021-08-18 15:59       ` Christian Borntraeger
2021-08-18 16:39         ` Alex Williamson
2021-08-18 16:50           ` Christian Borntraeger
2021-08-18 22:52             ` Halil Pasic
2021-08-19 15:30           ` Cornelia Huck
2021-08-20 14:24             ` Tony Krowiak

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