[PATCH v3 2/5] mdev: Make mdev alias unique among all mdevs

[Parav Pandit <parav@mellanox.com>]

Mdev alias should be unique among all the mdevs, so that when such alias
is used by the mdev users to derive other objects, there is no
collision in a given system.

Signed-off-by: Parav Pandit <parav@mellanox.com>

---
Changelog:
v2->v3:
 - Changed strcmp() ==0 to !strcmp()
v1->v2:
 - Moved alias NULL check at beginning
v0->v1:
 - Fixed inclusiong of alias for NULL check
 - Added ratelimited debug print for sha1 hash collision error
---
 drivers/vfio/mdev/mdev_core.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
index 3bdff0469607..c8cd40366783 100644
--- a/drivers/vfio/mdev/mdev_core.c
+++ b/drivers/vfio/mdev/mdev_core.c
@@ -388,6 +388,13 @@ int mdev_device_create(struct kobject *kobj, struct device *dev,
 			ret = -EEXIST;
 			goto mdev_fail;
 		}
+		if (alias && tmp->alias && !strcmp(alias, tmp->alias)) {
+			mutex_unlock(&mdev_list_lock);
+			ret = -EEXIST;
+			dev_dbg_ratelimited(dev, "Hash collision in alias creation for UUID %pUl\n",
+					    uuid);
+			goto mdev_fail;
+		}
 	}
 
 	mdev = kzalloc(sizeof(*mdev), GFP_KERNEL);
-- 
2.19.2