Messages in this thread | | | Subject | [QUESTION/sysfs] strange refcounting | From | "Artem B. Bityutskiy" <> | Date | Sat, 04 Feb 2006 11:13:41 +0300 |
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Hello folks,
I'm writing a simple device driver and want to expose some of its attributes to userspace via sysfs.
As usually, I have main device description structure "struct mydev_info". I've embedded a struct device object there. What I do is:
struct mydev_info mydev { struct device *dev; ... bla bla bla ... } mydev;
mydev->dev=kzalloc(sizeof(struct device), GFP_KERNEL); mydev->dev->bus_id = "mydev"; mydev->dev->release = mydev_release; err = device_register(&mydev->dev);
Then, I see /sys/devices/mydev/ in sysfs. I open pre-defined /sys/devices/mydev/power/state in userspace and don't close it.
Then I run lsmod, and see zero refcount to my module. Well, I run rmmod mymod, module is unloaded.
Then I close /sys/devices/mydev/power/state, and enjoy segfault.
I thought sysfs subsystem have to increase module refcount when one opens its sysfs files. Well, there is a release function, but it is also unloaded with the module.
May be there is a problem because of I have mydev->dev->parent == NULL, mydev->dev->bus == NULL, mydev->dev->driver == NULL? But I really don't have any bus, any parent and I don't want to introduce struct device_driver ...
Kernel is 2.6.15.1.
Although this is my first meet with sysfs, this looks strange.
Thanks.
-- Best Regards, Artem B. Bityuckiy, St.-Petersburg, Russia.
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