From: Jason Gunthorpe <jgg@nvidia.com>
To: Matthew Rosato <mjrosato@linux.ibm.com>
Cc: kvm@vger.kernel.org, linux-doc@vger.kernel.org,
David Airlie <airlied@linux.ie>,
"Tian, Kevin" <kevin.tian@intel.com>,
dri-devel@lists.freedesktop.org,
Kirti Wankhede <kwankhede@nvidia.com>,
Vineeth Vijayan <vneethv@linux.ibm.com>,
Alexander Gordeev <agordeev@linux.ibm.com>,
Christoph Hellwig <hch@lst.de>,
linux-s390@vger.kernel.org, "Liu, Yi L" <yi.l.liu@intel.com>,
Jonathan Corbet <corbet@lwn.net>,
Halil Pasic <pasic@linux.ibm.com>,
Christian Borntraeger <borntraeger@linux.ibm.com>,
intel-gfx@lists.freedesktop.org, Zhi Wang <zhi.a.wang@intel.com>,
Jason Herne <jjherne@linux.ibm.com>,
Eric Farman <farman@linux.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>,
Heiko Carstens <hca@linux.ibm.com>,
Alex Williamson <alex.williamson@redhat.com>,
Harald Freudenberger <freude@linux.ibm.com>,
Rodrigo Vivi <rodrigo.vivi@intel.com>,
intel-gvt-dev@lists.freedesktop.org,
Tony Krowiak <akrowiak@linux.ibm.com>,
Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>,
Cornelia Huck <cohuck@redhat.com>,
Peter Oberparleiter <oberpar@linux.ibm.com>,
Sven Schnelle <svens@linux.ibm.com>
Subject: Re: [PATCH 9/9] vfio: Remove calls to vfio_group_add_container_user()
Date: Thu, 14 Apr 2022 11:22:10 -0300 [thread overview]
Message-ID: <20220414142210.GE2120790@nvidia.com> (raw)
In-Reply-To: <d6e2778a-01e4-6468-2c2b-3b718d924e65@linux.ibm.com>
On Thu, Apr 14, 2022 at 09:51:49AM -0400, Matthew Rosato wrote:
> On 4/12/22 11:53 AM, Jason Gunthorpe wrote:
> > When the open_device() op is called the container_users is incremented and
> > held incremented until close_device(). Thus, so long as drivers call
> > functions within their open_device()/close_device() region they do not
> > need to worry about the container_users.
> >
> > These functions can all only be called between
> > open_device()/close_device():
> >
> > vfio_pin_pages()
> > vfio_unpin_pages()
> > vfio_dma_rw()
> > vfio_register_notifier()
> > vfio_unregister_notifier()
> >
> > So eliminate the calls to vfio_group_add_container_user() and add a simple
> > WARN_ON to detect mis-use by drivers.
> >
>
> vfio_device_fops_release decrements dev->open_count immediately before
> calling dev->ops->close_device, which means we could enter close_device with
> a dev_count of 0.
>
> Maybe vfio_device_fops_release should handle the same way as
> vfio_group_get_device_fd?
>
> if (device->open_count == 1 && device->ops->close_device)
> device->ops->close_device(device);
> device->open_count--;
Yes, thanks alot! I have nothing to test these flows on...
It matches the ordering in the only other place to call close_device.
I folded this into the patch:
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 0f735f9f206002..29761f0cf0a227 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -1551,8 +1551,9 @@ static int vfio_device_fops_release(struct inode *inode, struct file *filep)
mutex_lock(&device->dev_set->lock);
vfio_assert_device_open(device);
- if (!--device->open_count && device->ops->close_device)
+ if (device->open_count == 1 && device->ops->close_device)
device->ops->close_device(device);
+ device->open_count--;
mutex_unlock(&device->dev_set->lock);
module_put(device->dev->driver->owner);
Jason
next prev parent reply other threads:[~2022-04-14 14:22 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-12 15:53 [PATCH 0/9] Make the rest of the VFIO driver interface use vfio_device Jason Gunthorpe
2022-04-12 15:53 ` [PATCH 1/9] vfio: Make vfio_(un)register_notifier accept a vfio_device Jason Gunthorpe
[not found] ` <20220413055524.GB32092@lst.de>
2022-04-13 11:39 ` Jason Gunthorpe
[not found] ` <20220413160601.GA29631@lst.de>
2022-04-13 16:18 ` Jason Gunthorpe
[not found] ` <20220413162946.GB31053@lst.de>
2022-04-13 17:37 ` Jason Gunthorpe
2022-04-13 19:17 ` Wang, Zhi A
2022-04-13 20:04 ` Jason Gunthorpe
2022-04-13 21:08 ` Wang, Zhi A
2022-04-13 23:12 ` Jason Gunthorpe
2022-04-14 2:04 ` Tian, Kevin
2022-04-14 2:15 ` Tian, Kevin
2022-04-14 19:25 ` Eric Farman
2022-04-18 15:28 ` Tony Krowiak
2022-04-18 15:44 ` Jason Gunthorpe
2022-04-18 15:52 ` Tony Krowiak
2022-04-18 15:29 ` Jason J. Herne
2022-04-12 15:53 ` [PATCH 2/9] vfio/ccw: Remove mdev from struct channel_program Jason Gunthorpe
2022-04-14 19:25 ` Eric Farman
2022-04-12 15:53 ` [PATCH 3/9] vfio/mdev: Pass in a struct vfio_device * to vfio_pin/unpin_pages() Jason Gunthorpe
[not found] ` <20220413055717.GC32092@lst.de>
2022-04-13 11:40 ` Jason Gunthorpe
2022-04-14 19:26 ` Eric Farman
2022-04-18 15:25 ` Jason J. Herne
2022-04-19 17:00 ` Jason Gunthorpe
2022-04-18 15:56 ` Tony Krowiak
2022-04-12 15:53 ` [PATCH 4/9] drm/i915/gvt: Change from vfio_group_(un)pin_pages to vfio_(un)pin_pages Jason Gunthorpe
[not found] ` <20220413060110.GF32092@lst.de>
2022-04-13 13:39 ` Jason Gunthorpe
2022-04-12 15:53 ` [PATCH 5/9] vfio: Pass in a struct vfio_device * to vfio_dma_rw() Jason Gunthorpe
[not found] ` <20220413060008.GE32092@lst.de>
2022-04-13 13:39 ` Jason Gunthorpe
2022-04-12 15:53 ` [PATCH 6/9] drm/i915/gvt: Add missing module_put() in error unwind Jason Gunthorpe
2022-04-12 15:53 ` [PATCH 7/9] drm/i915/gvt: Delete kvmgt_vdev::vfio_group Jason Gunthorpe
2022-04-12 15:53 ` [PATCH 8/9] vfio: Remove dead code Jason Gunthorpe
2022-04-12 15:53 ` [PATCH 9/9] vfio: Remove calls to vfio_group_add_container_user() Jason Gunthorpe
[not found] ` <20220413061105.GA32701@lst.de>
2022-04-13 14:03 ` Jason Gunthorpe
2022-04-14 13:51 ` Matthew Rosato
2022-04-14 14:22 ` Jason Gunthorpe [this message]
2022-04-15 2:32 ` Tian, Kevin
2022-04-15 12:07 ` Jason Gunthorpe
2022-04-15 23:45 ` Tian, Kevin
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