Re: [PATCH 0/1] rust: block: mq: make GenDisk Send impl sound

[Andreas Hindborg <a.hindborg@kernel.org>]

Hi,

Yuan Tan <ytan089@ucr.edu> writes:

> Hi Linux kernel maintainers,
>
> We are developing a tool called FerroLens to detect potential unsound
> behavior in Rust code in the Linux kernel. FerroLens reported the following
> bug in rust/kernel/gendisk.rs.
>
> Gendisk is marked as Send although the fields it contains may not be.
> Specifically, the QueueData held in the raw gendisk pointer may not be safe
> to send across threads. Therefore, sending the Gendisk from one thread to
> another and dropping on a different thread may cause unsound behavior.
>
> Additionally, Gendisk contains an Arc<TagSet<T>>. This Arc would be Send
> and Sync if the underlying TagSet<T> were Send and Sync. But this is not
> explicitly derived, although it can be, since the API does not modify the
> TagSet.

Thanks for the patch. The `GenDisk` `Send` fix looks correct to me.

The implementation of `Send` and `Sync` for `TagSet` is not a fix, and
it was already sent to list [1]. It does however suffer the same issue
that you described for `GenDisk`, so I will address this when I send v2.

FYI, I did not receive your email in my inbox, I saw it on list. It
might be rejected by Proton for some reason.

Best regards,
Andreas Hindborg

[1] https://lore.kernel.org/rust-for-linux/20260216-rnull-v6-19-rc5-send-v1-42-de9a7af4b469@kernel.org/