This is just a bad driver model. There's no reason for a driver to have any complex data structures or structure lifetimes. Hardware is highly finite and static.
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The OS infrastructure using/interfacing with the drivers should be the component responsible for awareness of connections between hardware/drivers, user or kernel space consumers using the hardware, etc. and driver should have no access to these structures.
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Rust discourages having shared ownership (Rc, Arc), but there end up being use cases for it. It just isn't the normal way to design / implement things. It's painful to use Rust if you don't design things around simple ownership models because it forces it to be verified as safe.
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The code is very clean if you have unique ownership and use lots of lightweight references. If you have complex data structures, like linked data structures with cycles and mutability, you are forced into using Rc / RefCell or a similar approach which really discourages doing it.
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So for example, if you have a nice recursive tree data structure, you can represent that with the nodes as Box<T>, which is a uniquely owned dynamic allocation. If you want to have cycles back from the children to the parent nodes, you need Rc<T> with Weak<T> for parent pointers.
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So when you are actually using the parent pointer, you call upgrade(), which gives you an Option<Rc<T>> (since it might have been deallocated). You can do it, but you're encouraged to do things in a more simple way by the requirement for safety, like avoiding reference cycles.
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Honestly that's very complicated and would discourage me from using those conventions unless it's a project requirement or if the outcome was clearly positive.
I'll think about it more carefully. There's a lot I think I only partially understand here. 1/
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Well it's worth noting these are all library features and in a kernel you are only using libcore rather than libstd which builds on it. You'd want to smart pointers and collections returning Option from methods making them for handling out-of-memory without needing unwinding.
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Low-level library design for a low-level memory safe language is a very active ongoing research project. The ease of use and capabilities are advancing very quickly. I did a lot of work on it a few years ago including implementing iterator objects and a lot of collections, etc.
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Shared ownership / mutability is inherently complicated. It's very difficult to verify as correct, whether you're a compiler or a human. It ventures outside of what Rust can statically verify as correct without runtime overhead like references, Box<T>, Vec<T>, iterators, etc.
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Usually, the rules are all statically checked, such as the lifetime and aliasing rules for references, which compile down to raw pointers without instrumentation. If you want mutability in Rc<T>, that has to be dynamically checked, which is what Rc<RefCell<T>> provides.
So instead of &x, you get a reference with cell.borrow(), and a separate method for mutable references. It provides dynamic checking for the rule of preventing aliasing mutable references. If you avoid shared ownership, you avoid needing more verbose code and runtime checks.
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I think that’s what kernel programmers have elected to do as a best practice. Nearly all I know come from very technical backgrounds already before starting their kernel careers