Messages in this thread | | | Subject | Re: [PATCH] vfio/mtty: Enforce available_instances | From | Kirti Wankhede <> | Date | Mon, 28 Jun 2021 23:19:54 +0530 |
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On 6/26/2021 2:56 AM, Alex Williamson wrote: > The sample mtty mdev driver doesn't actually enforce the number of > device instances it claims are available. Implement this properly. > > Signed-off-by: Alex Williamson <alex.williamson@redhat.com> > --- > > Applies to vfio next branch + Jason's atomic conversion >
Does this need to be on top of Jason's patch? Patch to use mdev_used_ports is reverted here, can it be changed from mdev_devices_list to mdev_avail_ports atomic variable?
Change here to use atomic variable looks good to me.
Reviewed by: Kirti Wankhede <kwankhede@nvidia.com>
> samples/vfio-mdev/mtty.c | 22 ++++++++++++++++------ > 1 file changed, 16 insertions(+), 6 deletions(-) > > diff --git a/samples/vfio-mdev/mtty.c b/samples/vfio-mdev/mtty.c > index ffbaf07a17ea..8b26fecc4afe 100644 > --- a/samples/vfio-mdev/mtty.c > +++ b/samples/vfio-mdev/mtty.c > @@ -144,7 +144,7 @@ struct mdev_state { > int nr_ports; > }; > > -static atomic_t mdev_used_ports; > +static atomic_t mdev_avail_ports = ATOMIC_INIT(MAX_MTTYS); > > static const struct file_operations vd_fops = { > .owner = THIS_MODULE, > @@ -707,11 +707,20 @@ static int mtty_probe(struct mdev_device *mdev) > { > struct mdev_state *mdev_state; > int nr_ports = mdev_get_type_group_id(mdev) + 1; > + int avail_ports = atomic_read(&mdev_avail_ports); > int ret; > > + do { > + if (avail_ports < nr_ports) > + return -ENOSPC; > + } while (!atomic_try_cmpxchg(&mdev_avail_ports, > + &avail_ports, avail_ports - nr_ports)); > + > mdev_state = kzalloc(sizeof(struct mdev_state), GFP_KERNEL); > - if (mdev_state == NULL) > + if (mdev_state == NULL) { > + atomic_add(nr_ports, &mdev_avail_ports); > return -ENOMEM; > + } > > vfio_init_group_dev(&mdev_state->vdev, &mdev->dev, &mtty_dev_ops); > > @@ -724,6 +733,7 @@ static int mtty_probe(struct mdev_device *mdev) > > if (mdev_state->vconfig == NULL) { > kfree(mdev_state); > + atomic_add(nr_ports, &mdev_avail_ports); > return -ENOMEM; > } > > @@ -735,9 +745,9 @@ static int mtty_probe(struct mdev_device *mdev) > ret = vfio_register_group_dev(&mdev_state->vdev); > if (ret) { > kfree(mdev_state); > + atomic_add(nr_ports, &mdev_avail_ports); > return ret; > } > - atomic_add(mdev_state->nr_ports, &mdev_used_ports); > > dev_set_drvdata(&mdev->dev, mdev_state); > return 0; > @@ -746,12 +756,13 @@ static int mtty_probe(struct mdev_device *mdev) > static void mtty_remove(struct mdev_device *mdev) > { > struct mdev_state *mdev_state = dev_get_drvdata(&mdev->dev); > + int nr_ports = mdev_state->nr_ports; > > - atomic_sub(mdev_state->nr_ports, &mdev_used_ports); > vfio_unregister_group_dev(&mdev_state->vdev); > > kfree(mdev_state->vconfig); > kfree(mdev_state); > + atomic_add(nr_ports, &mdev_avail_ports); > } > > static int mtty_reset(struct mdev_state *mdev_state) > @@ -1271,8 +1282,7 @@ static ssize_t available_instances_show(struct mdev_type *mtype, > { > unsigned int ports = mtype_get_type_group_id(mtype) + 1; > > - return sprintf(buf, "%d\n", > - (MAX_MTTYS - atomic_read(&mdev_used_ports)) / ports); > + return sprintf(buf, "%d\n", atomic_read(&mdev_avail_ports) / ports); > } > > static MDEV_TYPE_ATTR_RO(available_instances); > >
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