[PATCH v6 0/6] rust: add improved version of `ForeignOwnable::borrow_mut`

[Tamir Duberstein <tamird@gmail.com>]

This is a re-submission of Alice's patch[0]. The leading commits are
intended to improve the consistency and ergonomics of `ForeignOwnable`,
and to split out the code movement originally included in the patch.

`ForeignOwnable::borrow_mut` is a dependency of the memory backing
feature of `rnull`, the Rust null block driver.

Link: https://lore.kernel.org/all/20230710074642.683831-1-aliceryhl@google.com/T/#u [0]

Signed-off-by: Tamir Duberstein <tamird@gmail.com>
---
Changes in v6:
- Rebase on linux-next, resolve conflict with f893691e7426 ("rust: miscdevice: add base miscdevice abstraction") [1]
- Link: https://lore.kernel.org/all/20241001-b4-miscdevice-v2-2-330d760041fa@google.com/ [1]
- Link to v5: https://lore.kernel.org/r/20241115-borrow-mut-v5-0-86204b249667@gmail.com

Changes in v5:
- Rebase on d072acda4862 ("rust: use custom FFI integer types") [0]
- Link: https://lore.kernel.org/all/20240913213041.395655-4-gary@garyguo.net/ [0]
- Link to v4: https://lore.kernel.org/r/20241110-borrow-mut-v4-0-053976068215@gmail.com

Changes in v4:
- Remove (another) superfluous `cast_const()`. (Alice Ryhl)
- Link to v3: https://lore.kernel.org/r/20241108-borrow-mut-v3-0-b7144945714e@gmail.com

Changes in v3:
- Remove superfluous `cast_const()`. (Alice Ryhl)
- Correct SoB placement. (Alice Ryhl)
- Mention `as` cast removal. (Miguel Ojeda)
- Link to v2: https://lore.kernel.org/r/20241104-borrow-mut-v2-0-de650678648d@gmail.com

Changes in v2:
- Call out ordering inconsistency in commit message.
- Restore pointer type ascriptionin Arc. (Andreas Hindborg)
- Remove most reduction of unsafe blocks. (Andreas Hindborg)
- Lift splitting of unsafe block into separate patch.
- Link to v1: https://lore.kernel.org/r/20241030-borrow-mut-v1-0-8f0ceaf78eaf@gmail.com

---
Alice Ryhl (1):
      rust: add improved version of `ForeignOwnable::borrow_mut`

Tamir Duberstein (5):
      rust: arc: use `NonNull::new_unchecked`
      rust: types: avoid `as` casts
      rust: arc: split unsafe block, add missing comment
      rust: change `ForeignOwnable` pointer to mut
      rust: reorder `ForeignOwnable` items

 rust/kernel/alloc/kbox.rs | 41 ++++++++++++++++-----
 rust/kernel/miscdevice.rs |  2 +-
 rust/kernel/sync/arc.rs   | 42 ++++++++++++++-------
 rust/kernel/types.rs      | 93 +++++++++++++++++++++++++++++++++++------------
 4 files changed, 130 insertions(+), 48 deletions(-)
---
base-commit: 7510705aa41f7891c84dbb37965f492f09ae2077
change-id: 20241030-borrow-mut-75f181feef4c

Best regards,
-- 
Tamir Duberstein <tamird@gmail.com>