Re: [PATCH v10 1/8] rust: types: add `NotThreadSafe`

[Gary Guo]

On Sun, 15 Sep 2024 14:31:27 +0000
Alice Ryhl <aliceryhl@xxxxxxxxxx> wrote:

> This introduces a new marker type for types that shouldn't be thread
> safe. By adding a field of this type to a struct, it becomes non-Send
> and non-Sync, which means that it cannot be accessed in any way from
> threads other than the one it was created on.
> 
> This is useful for APIs that require globals such as `current` to remain
> constant while the value exists.
> 
> We update two existing users in the Kernel to use this helper:
> 
>  * `Task::current()` - moving the return type of this value to a
>    different thread would not be safe as you can no longer be guaranteed
>    that the `current` pointer remains valid.
>  * Lock guards. Mutexes and spinlocks should be unlocked on the same
>    thread as where they were locked, so we enforce this using the Send
>    trait.
> 
> There are also additional users in later patches of this patchset. See
> [1] and [2] for the discussion that led to the introduction of this
> patch.
> 
> Link: https://lore.kernel.org/all/nFDPJFnzE9Q5cqY7FwSMByRH2OAn_BpI4H53NQfWIlN6I2qfmAqnkp2wRqn0XjMO65OyZY4h6P4K2nAGKJpAOSzksYXaiAK_FoH_8QbgBI4=@proton.me/ [1]
> Link: https://lore.kernel.org/all/nFDPJFnzE9Q5cqY7FwSMByRH2OAn_BpI4H53NQfWIlN6I2qfmAqnkp2wRqn0XjMO65OyZY4h6P4K2nAGKJpAOSzksYXaiAK_FoH_8QbgBI4=@proton.me/ [2]
> Suggested-by: Benno Lossin <benno.lossin@xxxxxxxxx>
> Reviewed-by: Benno Lossin <benno.lossin@xxxxxxxxx>
> Reviewed-by: Trevor Gross <tmgross@xxxxxxxxx>
> Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@xxxxxxxxx>
> Reviewed-by: Björn Roy Baron <bjorn3_gh@xxxxxxxxxxxxxx>
> Reviewed-by: Gary Guo <gary@xxxxxxxxxxx>
> Signed-off-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>

Miguel, can we apply this patch now without having it wait on the rest
of file abstractions because it'll be useful to other?

Best,
Gary

> ---
>  rust/kernel/sync/lock.rs | 13 +++++++++----
>  rust/kernel/task.rs      | 10 ++++++----
>  rust/kernel/types.rs     | 21 +++++++++++++++++++++
>  3 files changed, 36 insertions(+), 8 deletions(-)