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vfio/mtty: Enforce available_instances

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The sample mtty mdev driver doesn't actually enforce the number of
device instances it claims are available.  Implement this properly.

Link: https://lore.kernel.org/r/162465624894.3338367.12935940647049917981.stgit@omen
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed by: Kirti Wankhede <kwankhede@nvidia.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This commit is contained in:
Alex Williamson 2021-06-25 15:20:06 -06:00
parent 0dd1b7fc3e
commit 97d0a68744
1 changed files with 16 additions and 6 deletions
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22
samples/vfio-mdev/mtty.c
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@ -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);