Dan points out that an error case left things on this list. It is also
missing locking in available_instances_show().
Further study shows the list isn't needed at all, just store the total
ports in use in an atomic and delete the whole thing.
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Fixes: 09177ac91921 ("vfio/mtty: Convert to use vfio_register_group_dev()")
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
---
samples/vfio-mdev/mtty.c | 24 ++++++------------------
1 file changed, 6 insertions(+), 18 deletions(-)
diff --git a/samples/vfio-mdev/mtty.c b/samples/vfio-mdev/mtty.c
index faf9b8e8873a5b..ffbaf07a17eaee 100644
--- a/samples/vfio-mdev/mtty.c
+++ b/samples/vfio-mdev/mtty.c
@@ -144,8 +144,7 @@ struct mdev_state {
int nr_ports;
};
-static struct mutex mdev_list_lock;
-static struct list_head mdev_devices_list;
+static atomic_t mdev_used_ports;
static const struct file_operations vd_fops = {
.owner = THIS_MODULE,
@@ -733,15 +732,13 @@ static int mtty_probe(struct mdev_device *mdev)
mtty_create_config_space(mdev_state);
- mutex_lock(&mdev_list_lock);
- list_add(&mdev_state->next, &mdev_devices_list);
- mutex_unlock(&mdev_list_lock);
-
ret = vfio_register_group_dev(&mdev_state->vdev);
if (ret) {
kfree(mdev_state);
return ret;
}
+ atomic_add(mdev_state->nr_ports, &mdev_used_ports);
+
dev_set_drvdata(&mdev->dev, mdev_state);
return 0;
}
@@ -750,10 +747,8 @@ static void mtty_remove(struct mdev_device *mdev)
{
struct mdev_state *mdev_state = dev_get_drvdata(&mdev->dev);
+ atomic_sub(mdev_state->nr_ports, &mdev_used_ports);
vfio_unregister_group_dev(&mdev_state->vdev);
- mutex_lock(&mdev_list_lock);
- list_del(&mdev_state->next);
- mutex_unlock(&mdev_list_lock);
kfree(mdev_state->vconfig);
kfree(mdev_state);
@@ -1274,14 +1269,10 @@ static ssize_t available_instances_show(struct mdev_type *mtype,
struct mdev_type_attribute *attr,
char *buf)
{
- struct mdev_state *mds;
unsigned int ports = mtype_get_type_group_id(mtype) + 1;
- int used = 0;
- list_for_each_entry(mds, &mdev_devices_list, next)
- used += mds->nr_ports;
-
- return sprintf(buf, "%d\n", (MAX_MTTYS - used)/ports);
+ return sprintf(buf, "%d\n",
+ (MAX_MTTYS - atomic_read(&mdev_used_ports)) / ports);
}
static MDEV_TYPE_ATTR_RO(available_instances);
@@ -1395,9 +1386,6 @@ static int __init mtty_dev_init(void)
ret = mdev_register_device(&mtty_dev.dev, &mdev_fops);
if (ret)
goto err_device;
-
- mutex_init(&mdev_list_lock);
- INIT_LIST_HEAD(&mdev_devices_list);
return 0;
err_device:
--
2.32.0
