[PATCH v2] driver core: Fix error handling in driver API device_rename()

[Zijun Hu]

From: Zijun Hu <quic_zijuhu@xxxxxxxxxxx>

For class-device, device_rename() failure maybe cause unexpected link name
within its class folder as explained below:

/sys/class/.../old_name -> /sys/devices/.../old_name
device_rename(..., new_name) and failed
/sys/class/.../new_name -> /sys/devices/.../old_name

Fixed by undoing renaming link if renaming kobject failed.

Fixes: f349cf34731c ("driver core: Implement ns directory support for device classes.")
Signed-off-by: Zijun Hu <quic_zijuhu@xxxxxxxxxxx>
---
Changes in v2:
- Correct commit message and indentation
- Link to v1: https://lore.kernel.org/r/20240717-device_rename_fix-v1-1-54d85024518f@xxxxxxxxxxx
---
 drivers/base/core.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 2b4c0624b704..b335e239a633 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -4512,9 +4512,11 @@ EXPORT_SYMBOL_GPL(device_destroy);
  */
 int device_rename(struct device *dev, const char *new_name)
 {
+	struct subsys_private *sp = NULL;
 	struct kobject *kobj = &dev->kobj;
 	char *old_device_name = NULL;
 	int error;
+	bool is_link_renamed = false;
 
 	dev = get_device(dev);
 	if (!dev)
@@ -4529,7 +4531,7 @@ int device_rename(struct device *dev, const char *new_name)
 	}
 
 	if (dev->class) {
-		struct subsys_private *sp = class_to_subsys(dev->class);
+		sp = class_to_subsys(dev->class);
 
 		if (!sp) {
 			error = -EINVAL;
@@ -4538,16 +4540,19 @@ int device_rename(struct device *dev, const char *new_name)
 
 		error = sysfs_rename_link_ns(&sp->subsys.kobj, kobj, old_device_name,
 					     new_name, kobject_namespace(kobj));
-		subsys_put(sp);
 		if (error)
 			goto out;
+
+		is_link_renamed = true;
 	}
 
 	error = kobject_rename(kobj, new_name);
-	if (error)
-		goto out;
-
 out:
+	if (error && is_link_renamed)
+		sysfs_rename_link_ns(&sp->subsys.kobj, kobj, new_name,
+				     old_device_name, kobject_namespace(kobj));
+	subsys_put(sp);
+
 	put_device(dev);
 
 	kfree(old_device_name);

---
base-commit: 51835949dda3783d4639cfa74ce13a3c9829de00
change-id: 20240717-device_rename_fix-ecef084784e5

Best regards,
-- 
Zijun Hu <quic_zijuhu@xxxxxxxxxxx>