Messages in this thread | | | Date | Wed, 3 Nov 2021 10:25:47 -0300 | From | Jason Gunthorpe <> | Subject | Re: [RFC 02/20] vfio: Add device class for /dev/vfio/devices |
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On Tue, Nov 02, 2021 at 09:53:29AM +0000, Liu, Yi L wrote:
> > vfio_uninit_group_dev(&mdev_state->vdev); > > kfree(mdev_state->pages); > > kfree(mdev_state->vconfig); > > kfree(mdev_state); > > > > pages/vconfig would logically be in a release function > > I see. So the criteria is: the pointer fields pointing to a memory buffer > allocated by the device driver should be logically be free in a release > function. right?
Often yes, that is usually a good idea
>I can see there are such fields in struct vfio_pci_core_device > and mdev_state (both mbochs and mdpy). So we may go with your option #2. > Is it? otherwise, needs to add release callback for all the related drivers.
Yes, that is the approx trade off
> > On the other hand ccw needs to rcu free the vfio_device, so that would > > have to be global overhead with this api design. > > not quite get. why ccw is special here? could you elaborate?
I added a rcu usage to it in order to fix a race
+static inline struct vfio_ccw_private *vfio_ccw_get_priv(struct subchannel *sch) +{ + struct vfio_ccw_private *private; + + rcu_read_lock(); + private = dev_get_drvdata(&sch->dev); + if (private && !vfio_device_try_get(&private->vdev)) + private = NULL; + rcu_read_unlock(); + return private; +}
Jason
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