On 2019-08-28, Petr Mladek <[email protected]> wrote: > I only think that, especially, numlist API is too generic in v4. > It is not selfcontained. The consistency depends on external barriers. > > I believe that it might become fully self-contained and consistent > if we reduce possibilities of the generic usage. In particular, > the numlist should allow only linking of reusable structures > stored in an array.
OK. I will make the numlist the master of the ID-to-node mapping. To implement the getdesc() callback of the dataring, the printk_ringbuffer can call a numlist mapping function. Also, numlist will need to provide a function to bump the descriptor version (as your previous idea already showed). I plan to change the array to be numlist nodes. The ID would move into the numlist node structure and a void-pointer private would be added so that the numlist user can add private data (for printk_ringbuffer that would just be a pointer to the dataring structure). When the printk_ringbuffer gets a never-used numlist node, it can set the private field. This has the added benefit of making it easy to detect accidental never-used descriptor usage when reading dataring garbage. This was non-trivial and I'm still not sure I solved it correctly. (I've already spent a week working on a definitive answer to your email[0] asking about this.) John Ogness [0] https://lkml.kernel.org/r/[email protected]
