Hi Hans, I think the memory allocated with kzalloc is properly freed by calling kobject_put.
I can give a simple explanation. 1) when we call kobject_init, the parameter portio_attr_type is passed in. portio_attr_type includes a function pointer to portio_release, which releases the memory of portio. 2) when we call kobject_put, kref_put is called with the pointer of function kobject_release. 3) kref_put calls kref_sub, with the same pointer of function kobject_release. 4) and kref_put calls the function kboject_release if atomic_sub_and_test returns true 5) let's look at what kobject_release is. it calls kobject_cleanup, and kobject_cleanup calls t->release(kobj) where t->release is exactly the function we passed in through portio_init at step (1). so function portio_release is called, and the memory allocated with kzalloc is freed. If there are anything wrong in my analysis, please feel free to let me know. Personally, I suggest to add a function to create and release uio_portio, which is similar as kobject_create and kobject_put in file lib/kobject.c. In this way, it avoid other readers thinking the memory is not freed (and we should add some comments here). For example, uio_portio_create call kzalloc and kboject_init, and returns uio_portio, which is similar as function kobject_create; and uio_portio_release calls kobject_put to release the memory. And we do same thing for uio_map. The usage here is quite strange, but it works. If I write this function from zero, I will use a pointer to kobject in uio_portio struct instead of kobject struct itself. In this case I can call kobject_create instead of kobject_init, and then we do both kzalloc(uio_portio) and kfree(uio_portio) in the file uio.c. Best, Cong On Fri, Nov 30, 2012 at 1:13 AM, Hans J. Koch <h...@hansjkoch.de> wrote: > There's still another bug: The memory allocated with kzalloc is > never freed. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
