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rust: block: fix Send bound for GenDisk

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The `Send` implementation for `GenDisk<T>` was conditioned on `T: Send`.
This constrains the wrong type. `T` is the `Operations` implementation,
which is typically a zero-sized marker type that carries no data, so `T:
Send` says nothing about whether the data a `GenDisk` actually owns can be
moved to another thread.

A `GenDisk<T>` owns the queue data `T::QueueData` (stored as the
`gendisk`'s `queuedata` and dropped when the `GenDisk` is dropped) and an
`Arc<TagSet<T>>`. These are the values transferred when a `GenDisk` is sent
across a thread boundary, so the `Send` bound must constrain exactly them.
Bound `T::QueueData: Send` and `Arc<TagSet<T>>: Send` instead.

Fixes: 3253aba340 ("rust: block: introduce `kernel::block::mq` module")
Cc: stable@vger.kernel.org
Reported-by: Priya Bala Govindasamy <pgovind2@uci.edu>, Dylan Zueck <dzueck@uci.edu>, Yuan Tan <ytan089@ucr.edu>
Closes: https://lore.kernel.org/all/cover.1780633578.git.ytan089@ucr.edu
Signed-off-by: Yuan Tan <ytan089@ucr.edu>
Link: https://msgid.link/20260709100100.604252-1-yuantan098@gmail.com
[ Andreas: Fix tags to make checkpatch happy. Change summary line. ]
Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>
Link: https://patch.msgid.link/20260929-rust-block-for-v7-4-rc1-b4-v1-4-642a4c1aebd7@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Andreas Hindborg 2026-09-29 11:34:02 +02:00 committed by Jens Axboe
parent a463f71c49
commit e502b667ee
1 changed files with 8 additions and 2 deletions
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10
rust/kernel/block/mq/gen_disk.rs
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@ -224,8 +224,14 @@ pub struct GenDisk<T: Operations> {
}
// SAFETY: `GenDisk` is an owned pointer to a `struct gendisk` and an `Arc` to a
// `TagSet` It is safe to send this to other threads as long as T is Send.
unsafe impl<T: Operations + Send> Send for GenDisk<T> {}
// `TagSet`. It is safe to send this to other threads as long as these two are `Send`.
unsafe impl<T> Send for GenDisk<T>
where
T: Operations,
T::QueueData: Send,
Arc<TagSet<T>>: Send,
{
}
impl<T: Operations> Drop for GenDisk<T> {
fn drop(&mut self) {