Currently there is no good way to pass arbitrary data from the driver to
a `miscdevice` or to share data between individual handles to a
`miscdevice` in rust.
This series adds additional (generic) data to the MiscDeviceRegistration
for this purpose.
The first patch originally comes from my `UnsafePinned` patch series [0].
The second patch implements the changes and fixes the build of the sample
without changing any functionality (this is currently the only in tree
user).
The third patch changes the `rust_misc_device` sample to use this to
share the same data between multiple handles to the `miscdevice`.
I have tested the sample with qemu and the C userspace example
from the doc comments.
Some discussion on Zulip about the motivation and approach [1].
Thanks a lot to everyone helping me out with this.
This patch series is based on the rust-next branch.
Link: https://lore.kernel.org/rust-for-linux/20250511-rust_unsafe_pinned-v4-2-a86c32e47e3d@gmail.com/ [0]
Link: https://rust-for-linux.zulipchat.com/#narrow/channel/288089-General/topic/Passing.20a.20DevRes.20to.20a.20miscdev/near/494553814 [1]
Signed-off-by: Christian Schrefl <chrisi.schrefl@gmail.com>
---
Changes in v4:
- Rework to use Opaque instead of `UnsafePinned`.
- Include `impl Wrapper for Opaque` patch.
- Link to v3: https://lore.kernel.org/r/20250517-b4-rust_miscdevice_registrationdata-v3-0-cdb33e228d37@gmail.com
Changes in v3:
- Rebased on top of my `UnsafePinned` series.
- Link to v2: https://lore.kernel.org/r/20250131-b4-rust_miscdevice_registrationdata-v2-0-588f1e6cfabe@gmail.com
Changes in v2:
- Don't use associated_type_bounds since the MSRV does not support
that on stable yet (Kernel test robot)
- Doc changes and add intra-doc links (Miguel)
- Use container_of macro instead of pointer cast in `fops_open` (Greg)
- Rename `Aliased` to `UnsafePinned` (Boqun)
- Make sure Data is initialized before `misc_register` is called
- Rework the example to use an additional shared value instead of
replacing the unique one
- Expanded the c code for the example to use the new ioctls
- Link to v1: https://lore.kernel.org/r/20250119-b4-rust_miscdevice_registrationdata-v1-0-edbf18dde5fc@gmail.com
---
Christian Schrefl (3):
rust: implement `Wrapper<T>` for `Opaque<T>`
rust: miscdevice: add additional data to MiscDeviceRegistration
rust: miscdevice: adjust the rust_misc_device sample to use RegistrationData.
rust/kernel/miscdevice.rs | 79 +++++++++++++++++++-------
rust/kernel/revocable.rs | 2 +
rust/kernel/types.rs | 25 ++++----
samples/rust/rust_misc_device.rs | 120 ++++++++++++++++++++++++++++++++++++---
4 files changed, 185 insertions(+), 41 deletions(-)
---
base-commit: a3b2347343e077e81d3c169f32c9b2cb1364f4cc
change-id: 20250119-b4-rust_miscdevice_registrationdata-a11d88dcb284
Best regards,
--
Christian Schrefl <chrisi.schrefl@gmail.com>