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From: Jason Gunthorpe <jgg@nvidia.com>
To: "Tian, Kevin" <kevin.tian@intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>,
	David Airlie <airlied@linux.ie>,
	Alex Williamson <alex.williamson@redhat.com>,
	Christian Borntraeger <borntraeger@linux.ibm.com>,
	Cornelia Huck <cohuck@redhat.com>,
	Jonathan Corbet <corbet@lwn.net>, Daniel Vetter <daniel@ffwll.ch>,
	"dri-devel@lists.freedesktop.org"
	<dri-devel@lists.freedesktop.org>,
	Harald Freudenberger <freude@linux.ibm.com>,
	Vasily Gorbik <gor@linux.ibm.com>,
	Heiko Carstens <hca@linux.ibm.com>,
	"intel-gfx@lists.freedesktop.org"
	<intel-gfx@lists.freedesktop.org>,
	"intel-gvt-dev@lists.freedesktop.org" 
	<intel-gvt-dev@lists.freedesktop.org>,
	Jani Nikula <jani.nikula@linux.intel.com>,
	Jason Herne <jjherne@linux.ibm.com>,
	Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	Kirti Wankhede <kwankhede@nvidia.com>,
	"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
	"linux-s390@vger.kernel.org" <linux-s390@vger.kernel.org>,
	Matthew Rosato <mjrosato@linux.ibm.com>,
	Peter Oberparleiter <oberpar@linux.ibm.com>,
	Halil Pasic <pasic@linux.ibm.com>,
	"Vivi, Rodrigo" <rodrigo.vivi@intel.com>,
	Sven Schnelle <svens@linux.ibm.com>,
	Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>,
	Vineeth Vijayan <vneethv@linux.ibm.com>,
	Zhenyu Wang <zhenyuw@linux.intel.com>,
	"Wang, Zhi A" <zhi.a.wang@intel.com>,
	Tony Krowiak <akrowiak@linux.ibm.com>,
	Eric Farman <farman@linux.ibm.com>,
	Christoph Hellwig <hch@lst.de>, "Liu, Yi L" <yi.l.liu@intel.com>
Subject: Re: [PATCH v2 7/7] vfio: Remove calls to vfio_group_add_container_user()
Date: Fri, 22 Apr 2022 17:55:33 -0300	[thread overview]
Message-ID: <20220422205533.GE1951132@nvidia.com> (raw)
In-Reply-To: <BN9PR11MB52760B405E5F68C2155492078CF79@BN9PR11MB5276.namprd11.prod.outlook.com>

On Fri, Apr 22, 2022 at 02:11:27AM +0000, Tian, Kevin wrote:

> >  	mutex_lock(&device->dev_set->lock);
> > -	if (!--device->open_count && device->ops->close_device)
> > +	vfio_assert_device_open(device);
> > +	if (device->open_count == 1 && device->ops->close_device)
> >  		device->ops->close_device(device);
> > +	device->open_count--;
> >  	mutex_unlock(&device->dev_set->lock);
> 
> Is it necessary to add assertion here? This is the only place to
> decrement the counter and no similar assertion in other release()/
> put() functions.

Necessary, no, but since we have it we may as well check it here. It
is common to check that refcounts don't underflow.

Jason

  reply	other threads:[~2022-04-22 22:06 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-21 16:28 [PATCH v2 0/7] Make the rest of the VFIO driver interface use vfio_device Jason Gunthorpe
2022-04-21 16:28 ` [PATCH v2 1/7] vfio: Make vfio_(un)register_notifier accept a vfio_device Jason Gunthorpe
2022-04-22  1:39   ` Tian, Kevin
2022-04-22 17:07     ` Jason Gunthorpe
2022-04-22  6:21   ` Christoph Hellwig
2022-04-21 16:28 ` [PATCH v2 2/7] vfio/ccw: Remove mdev from struct channel_program Jason Gunthorpe
2022-04-21 16:28 ` [PATCH v2 3/7] vfio/mdev: Pass in a struct vfio_device * to vfio_pin/unpin_pages() Jason Gunthorpe
2022-04-22  1:43   ` Tian, Kevin
2022-04-22  6:22   ` Christoph Hellwig
2022-04-22 20:56     ` Jason Gunthorpe
2022-04-23  5:15       ` Christoph Hellwig
2022-04-23 12:49         ` Jason Gunthorpe
2022-04-21 16:28 ` [PATCH v2 4/7] vfio/mdev: Pass in a struct vfio_device * to vfio_dma_rw() Jason Gunthorpe
2022-04-22  1:50   ` Tian, Kevin
2022-04-22 17:59     ` Jason Gunthorpe
2022-04-24  5:52       ` Tian, Kevin
2022-04-21 16:28 ` [PATCH v2 5/7] drm/i915/gvt: Change from vfio_group_(un)pin_pages to vfio_(un)pin_pages Jason Gunthorpe
2022-04-22  1:51   ` Tian, Kevin
2022-04-22  6:22   ` Christoph Hellwig
2022-04-21 16:28 ` [PATCH v2 6/7] vfio: Remove dead code Jason Gunthorpe
2022-04-22  1:52   ` Tian, Kevin
2022-04-21 16:28 ` [PATCH v2 7/7] vfio: Remove calls to vfio_group_add_container_user() Jason Gunthorpe
2022-04-22  2:11   ` Tian, Kevin
2022-04-22 20:55     ` Jason Gunthorpe [this message]
2022-04-29 20:28   ` Alex Williamson
2022-05-02 16:22     ` Jason Gunthorpe
2022-04-29 17:31 ` [PATCH v2 0/7] Make the rest of the VFIO driver interface use vfio_device Jason Gunthorpe
2022-04-29 22:22   ` Alex Williamson

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