Hi all. Please forgive my lenghty message due to my poor knowledge of the English language that prevents me from being more straightforward and brief. In hacking Linux code often we have to access data structures and variables embedded in them. We all know that most of these objects need some special attention when manipulating them, like previous verifying of some particular condition, acquiring locks, atomically r/w and so on. This is why developers of core structure usually provide some standardized controlled data access method as macros and as other function interfaces. As an example (maybe it is not the most appropriate), "set_task_state(task, state)" not only sets the given task the given state, it also provide a memory barrier() when needed (SMP). If I am not missing something, only on UP it is a simpler "task->state = state". The problem is that any client code handling the variable "task->state" could change its value without being forced to only use the set_task_state() macro. This may well be a bug. Obviously the example can be extended to any data variable that needs particular care in dealing with. Someone hacking kernel code might not even know that a special interface has been created and should be used. Those interfaces are disseminated in headers so that overlooking them might be not so exceptional. Sometimes it also happens to me to miss the existence of an interface and so I write code that directly manipulate that data which only by chance, often either from reading code developed by others or when debugging something that doesn't work, I eventually find the proper way to access. Now I have three question: 1) Is what I discuss here a perceived problem? Am I missing something that makes this a no problem? 2) Is it possible to enforce, in client's code, the use of the proper interfaces to core kernel structures? (I mean something like the object oriented language as C++ do with "private" objects embedded data that can only be initialised, accessed and finalized by public interfaces). 3) If both C language and GCC extension couldn't help, is there any idea for practical solutions within Linux kernel? Thank you for your kind attention. fabio -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
