On Sat, Jan 11, 2020 at 10:48:37AM +0800, Zhangfei Gao wrote:The refcount here is preventing rmmod "parent" module after fd is opened,
+static int uacce_fops_open(struct inode *inode, struct file *filep)Why are you trying to grab the module reference of the parent device?
+{
+ struct uacce_mm *uacce_mm = NULL;
+ struct uacce_device *uacce;
+ struct uacce_queue *q;
+ int ret = 0;
+
+ uacce = xa_load(&uacce_xa, iminor(inode));
+ if (!uacce)
+ return -ENODEV;
+
+ if (!try_module_get(uacce->parent->driver->owner))
+ return -ENODEV;
Why is that needed and what is that going to help with here?
This shouldn't be needed as the module reference of the owner of the
fileops for this module is incremented, and the "parent" module depends
on this module, so how could it be unloaded without this code being
unloaded?
Yes, if you build this code into the kernel and the "parent" driver is a
module, then you will not have a reference, but when you remove that
parent driver the device will be removed as it has to be unregistered
before that parent driver can be removed from the system, right?
Or what am I missing here?
Yes, this is a mistake.
+static void uacce_release(struct device *dev)That line didn't do anything :)
+{
+ struct uacce_device *uacce = to_uacce_device(dev);
+
+ kfree(uacce);
+ uacce = NULL;