The subject line is missing the loop: prefix.
This approach looks very reasonable, but a few comments below:
> - lo->workqueue = alloc_workqueue("loop%d",
> - WQ_UNBOUND | WQ_FREEZABLE,
> - 0,
> - lo->lo_number);
> + if (!lo->workqueue)
> + lo->workqueue = alloc_workqueue("loop%d",
> + WQ_UNBOUND | WQ_FREEZABLE,
> + 0, lo->lo_number);
Instead of having to deal with sometimes present workqueues, why
not move the workqueue allocation to loop_add?
> + /* This is safe: open() is still holding a reference. */
> + module_put(THIS_MODULE);
Any reason to move the module_put here insted of keeping it at the
end of the function as the old code did?
