On 2022/6/27 下午9:21, Greg Kroah-Hartman wrote:
On Fri, Jun 24, 2022 at 10:21:21PM +0800, Zhangfei Gao wrote:
Change cdev owner to parent driver owner, which blocks rmmod parent
driver module once fd is opened.
Signed-off-by: Yang Shen <shenyang39@xxxxxxxxxx>
Signed-off-by: Zhangfei Gao <zhangfei.gao@xxxxxxxxxx>
---
drivers/misc/uacce/uacce.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/misc/uacce/uacce.c b/drivers/misc/uacce/uacce.c
index 281c54003edc..f82f2dd30e76 100644
--- a/drivers/misc/uacce/uacce.c
+++ b/drivers/misc/uacce/uacce.c
@@ -484,7 +484,7 @@ int uacce_register(struct uacce_device *uacce)
return -ENOMEM;
uacce->cdev->ops = &uacce_fops;
- uacce->cdev->owner = THIS_MODULE;
+ uacce->cdev->owner = uacce->parent->driver->owner;
What if parent is not set? What if parent does not have a driver set to
it yet? Why would a device's parent module control the lifespan of this
child device's cdev?
Have used try_module_get(uacce->parent->driver->owner) in open, and
module_put in release.
Seems same issue.
This feels wrong and like a layering violation here.
If a parent's module is unloaded, then invalidate the cdev for the
device when you tear it down before the module is unloaded.
Yes, make sense.
Yes, the interaction between the driver model and a cdev is messy, and
always tricky (see the recent ksummit discussion about this again, and
last year's discussion), but that does not mean you should add laying
violations like this to the codebase. Please fix this properly.
Thanks Greg
Yes, I was in hesitation whether adding the patch 1, but it looks very
simple.
In fact, the patch 2 can cover both removing device and rmmod parent
driver module.
We can just keep patch 2.
Thanks
