netdev - Re: [PATCH 0/5] Rust abstractions for network device drivers

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Message-ID: <809bb749-365f-af06-c575-0c4b1a219035@ryhl.io>
Date: Tue, 20 Jun 2023 18:56:11 +0200
From: Alice Ryhl <alice@...l.io>
To: Jakub Kicinski <kuba@...nel.org>
Cc: Andrew Lunn <andrew@...n.ch>, FUJITA Tomonori
 <fujita.tomonori@...il.com>, netdev@...r.kernel.org,
 rust-for-linux@...r.kernel.org, aliceryhl@...gle.com,
 miguel.ojeda.sandonis@...il.com
Subject: Re: [PATCH 0/5] Rust abstractions for network device drivers

On 6/20/23 17:47, Jakub Kicinski wrote:
> On Sat, 17 Jun 2023 12:08:26 +0200 Alice Ryhl wrote:
>>> The drop reason indicates why the packet was dropped. It should give
>>> some indication of what problem occurred which caused the drop. So
>>> ideally we don't want an anonymous drop. The C code does not enforce
>>> that, but it would be nice if the rust wrapper to dispose of an skb
>>> did enforce it.
>>
>> It sounds like a destructor with WARN_ON is the best approach right now.
>>
>> Unfortunately, I don't think we can enforce that the destructor is not
>> used today. That said, in the future it may be possible to implement a
>> linter that detects it - I know that there have already been experiments
>> with other custom lints for the kernel (e.g., enforcing that you don't
>> sleep while holding a spinlock).
> 
> Can we do something to hide the destructor from the linker?

We could probably have the destructor call some method that the linker 
wont be able to find, then mark the destructor with #[inline] so that 
dead-code elimination removes it if unused.

(At least, in godbolt the inline marker was necessary for the destructor 
to get removed when not used.)