linux/rust/kernel/miscdevice.rs, branch v6.14

Merge tag 'driver-core-6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

2025-01-28T20:25:12Z

Pull driver core and debugfs updates from Greg KH: "Here is the big set of driver core and debugfs updates for 6.14-rc1. Included in here is a bunch of driver core, PCI, OF, and platform rust bindings (all acked by the different subsystem maintainers), hence the merge conflict with the rust tree, and some driver core api updates to mark things as const, which will also require some fixups due to new stuff coming in through other trees in this merge window. There are also a bunch of debugfs updates from Al, and there is at least one user that does have a regression with these, but Al is working on tracking down the fix for it. In my use (and everyone else's linux-next use), it does not seem like a big issue at the moment. Here's a short list of the things in here: - driver core rust bindings for PCI, platform, OF, and some i/o functions. We are almost at the "write a real driver in rust" stage now, depending on what you want to do. - misc device rust bindings and a sample driver to show how to use them - debugfs cleanups in the fs as well as the users of the fs api for places where drivers got it wrong or were unnecessarily doing things in complex ways. - driver core const work, making more of the api take const * for different parameters to make the rust bindings easier overall. - other small fixes and updates All of these have been in linux-next with all of the aforementioned merge conflicts, and the one debugfs issue, which looks to be resolved "soon"" * tag 'driver-core-6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (95 commits) rust: device: Use as_char_ptr() to avoid explicit cast rust: device: Replace CString with CStr in property_present() devcoredump: Constify 'struct bin_attribute' devcoredump: Define 'struct bin_attribute' through macro rust: device: Add property_present() saner replacement for debugfs_rename() orangefs-debugfs: don't mess with ->d_name octeontx2: don't mess with ->d_parent or ->d_parent->d_name arm_scmi: don't mess with ->d_parent->d_name slub: don't mess with ->d_name sof-client-ipc-flood-test: don't mess with ->d_name qat: don't mess with ->d_name xhci: don't mess with ->d_iname mtu3: don't mess wiht ->d_iname greybus/camera - stop messing with ->d_iname mediatek: stop messing with ->d_iname netdevsim: don't embed file_operations into your structs b43legacy: make use of debugfs_get_aux() b43: stop embedding struct file_operations into their objects carl9170: stop embedding file_operations into their objects ...

rust: kernel: change `ForeignOwnable` pointer to mut

2025-01-13T22:45:31Z

It is slightly more convenient to operate on mut pointers, and this also properly conveys the desired ownership semantics of the trait. Reviewed-by: Alice Ryhl Reviewed-by: Andreas Hindborg Signed-off-by: Tamir Duberstein Acked-by: Danilo Krummrich Link: https://lore.kernel.org/r/20241120-borrow-mut-v6-4-80dbadd00951@gmail.com [ Reworded title slightly. - Miguel ] Signed-off-by: Miguel Ojeda

miscdevice: rust: use build_error! macro instead of function

2025-01-10T12:23:57Z

The function called build_error is an implementation detail of the macro of the same name. Thus, update miscdevice to use the macro rather than the function. See [1] for more information on this. These use the macro with the kernel:: prefix as it has not yet been added to the prelude. Reported-by: Stephen Rothwell Link: https://lore.kernel.org/r/20250110162828.38614c1b@canb.auug.org.au Link: https://lore.kernel.org/all/20241123222849.350287-2-ojeda@kernel.org/ [1] Signed-off-by: Alice Ryhl Acked-by: Miguel Ojeda Link: https://lore.kernel.org/r/20250110101459.536726-1-aliceryhl@google.com Signed-off-by: Greg Kroah-Hartman

rust: add `build_error!` to the prelude

2025-01-09T23:19:09Z

The sibling `build_assert!` is already in the prelude, it makes sense that a "core"/"language" facility like this is part of the prelude and users should not be defining their own one (thus there should be no risk of future name collisions and we would want to be aware of them anyway). Thus add `build_error!` into the prelude. Reviewed-by: Alice Ryhl Link: https://lore.kernel.org/r/20241123222849.350287-3-ojeda@kernel.org [ Applied the change to the new miscdevice cases. - Miguel ] Signed-off-by: Miguel Ojeda

rust: use the `build_error!` macro, not the hidden function

2025-01-09T23:19:05Z

Code and some examples were using the function, rather than the macro. The macro is what is documented. Thus move users to the macro. Reviewed-by: Alice Ryhl Link: https://lore.kernel.org/r/20241123222849.350287-1-ojeda@kernel.org [ Applied the change to the new miscdevice cases. - Miguel ] Signed-off-by: Miguel Ojeda

rust: map `long` to `isize` and `char` to `u8`

2024-12-16T20:49:33Z

The following FFI types are replaced compared to `core::ffi`: 1. `char` type is now always mapped to `u8`, since kernel uses `-funsigned-char` on the C code. `core::ffi` maps it to platform default ABI, which can be either signed or unsigned. 2. `long` is now always mapped to `isize`. It's very common in the kernel to use `long` to represent a pointer-sized integer, and in fact `intptr_t` is a typedef of `long` in the kernel. Enforce this mapping rather than mapping to `i32/i64` depending on platform can save us a lot of unnecessary casts. Signed-off-by: Gary Guo Reviewed-by: Alice Ryhl Link: https://lore.kernel.org/r/20240913213041.395655-5-gary@garyguo.net [ Moved `uaccess` changes from the next commit, since they were irrefutable patterns that Rust >= 1.82.0 warns about. Reworded slightly and reformatted a few documentation comments. Rebased on top of `rust-next`. Added the removal of two casts to avoid Clippy warnings. - Miguel ] Signed-off-by: Miguel Ojeda

rust: finish using custom FFI integer types

2024-12-16T20:48:45Z

In the last kernel cycle we migrated most of the `core::ffi` cases in commit d072acda4862 ("rust: use custom FFI integer types"): Currently FFI integer types are defined in libcore. This commit creates the `ffi` crate and asks bindgen to use that crate for FFI integer types instead of `core::ffi`. This commit is preparatory and no type changes are made in this commit yet. Finish now the few remaining/new cases so that we perform the actual remapping in the next commit as planned. Acked-by: Jocelyn Falempe # drm Link: https://lore.kernel.org/rust-for-linux/CANiq72m_rg42SvZK=bF2f0yEoBLVA33UBhiAsv8THhVu=G2dPA@mail.gmail.com/ Link: https://lore.kernel.org/all/cc9253fa-9d5f-460b-9841-94948fb6580c@redhat.com/ Signed-off-by: Miguel Ojeda

rust: miscdevice: add fops->show_fdinfo() hook

2024-12-16T15:12:57Z

File descriptors should generally provide a fops->show_fdinfo() hook for debugging purposes. Thus, add such a hook to the miscdevice abstractions. Signed-off-by: Alice Ryhl Link: https://lore.kernel.org/r/20241203-miscdevice-showfdinfo-v1-1-7e990732d430@google.com Signed-off-by: Greg Kroah-Hartman

rust: miscdevice: Provide accessor to pull out miscdevice::this_device

2024-12-16T15:12:34Z

There are situations where a pointer to a `struct device` will become necessary (e.g. for calling into dev_*() functions). This accessor allows callers to pull this out from the `struct miscdevice`. Signed-off-by: Lee Jones Signed-off-by: Alice Ryhl Tested-by: Lee Jones Reviewed-by: Danilo Krummrich Link: https://lore.kernel.org/r/20241210-miscdevice-file-param-v3-3-b2a79b666dc5@google.com Signed-off-by: Greg Kroah-Hartman

rust: miscdevice: access the `struct miscdevice` from fops->open()

2024-12-16T15:12:30Z

Providing access to the underlying `struct miscdevice` is useful for various reasons. For example, this allows you access the miscdevice's internal `struct device` for use with the `dev_*` printing macros. Note that since the underlying `struct miscdevice` could get freed at any point after the fops->open() call (if misc_deregister is called), only the open call is given access to it. To use `dev_*` printing macros from other fops hooks, take a refcount on `miscdevice->this_device` to keep it alive. See the linked thread for further discussion on the lifetime of `struct miscdevice`. Link: https://lore.kernel.org/r/2024120951-botanist-exhale-4845@gregkh Signed-off-by: Alice Ryhl Reviewed-by: Lee Jones Tested-by: Lee Jones Reviewed-by: Danilo Krummrich Link: https://lore.kernel.org/r/20241210-miscdevice-file-param-v3-2-b2a79b666dc5@google.com Signed-off-by: Greg Kroah-Hartman