On Mon, Mar 24, 2025 at 4:16 PM Benno Lossin benno.lossin@proton.me wrote:
On Mon Mar 17, 2025 at 3:23 PM CET, Tamir Duberstein wrote:
This started with a patch that enabled `clippy::ptr_as_ptr`. Benno Lossin suggested I also look into `clippy::ptr_cast_constness` and I discovered `clippy::as_ptr_cast_mut`. This series now enables all 3 lints. It also enables `clippy::as_underscore` which ensures other pointer casts weren't missed. The first commit reduces the need for pointer casts and is shared with another series[1].
The final patch also enables pointer provenance lints and fixes violations. See that commit message for details. The build system portion of that commit is pretty messy but I couldn't find a better way to convincingly ensure that these lints were applied globally. Suggestions would be very welcome.
I applied the patches to v6.14-rc7 and did a quick pass with
rg -nC 3 -t rust ' as ' | bat -l rustto see if there are any cases left that we could fix and I found a couple:
- there are several cases of `number as int_type` (like `num as c_int` or `my_u32 as usize` etc.) not sure what we can do about these, some are probably unavoidable, but since the kernel doesn't support 16 bit systems (that is true, right?), we *could* have a `From<u32> for usize` impl...
Yeah, these are the most difficult ones to get rid of.
- some instances of `'|' as u32` (samples/rust/rust_misc_device.rs:112). There is a `From<char> for u32` impl, so this can just be replaced with `.into()` (or maybe by using a byte literal `b'|'`?).
We can enable https://rust-lang.github.io/rust-clippy/master/index.html?levels=allow#cast_... for this one.
- `shared_ref as *const _` (for example in rust/kernel/uaccess.rs:247, rust/kernel/str.rs:32 and rust/kernel/fs/file.rs:367), these we can replace with `let ptr: *const ... = shared_ref;`. Don't know if there is a clippy lint for this.
I think there's not a focused one. There's a nuclear option: https://rust-lang.github.io/rust-clippy/master/index.html?levels=allow#as_co...
- some pointer casts in rust/kernel/list/impl_list_item_mod.rs:{253,254} not sure if they can be converted though (maybe they are unsizing the pointer?)
I have a local series that gets rid of these by doing similar things to https://lore.kernel.org/all/20250307-no-offset-v1-0-0c728f63b69c@gmail.com/. I can send it later this week but it probably can't land until Alice is back from vacation; she was the author of this code.
Another pointer cast in rust/kernel/driver.rs:81 (I'm pretty sure this one can be replaced by a `.cast()`)
Some clippy lints that we could also enable that share the spirit of this series:
- `char_lit_as_u8` (maybe that also covers the `'|' as u32` case from above?)
It's already enabled, it's warn-by-default.
- `cast_lossless` (maybe this catches some of the `num as int_type` conversions I mentioned above)
Yeah, suggested the same above. I had hoped this would deal with the char as u32 pattern but it did not.
I'll leave it up to you what you want to do with this: add it to this series, make a new one, or let someone else handle it. If you don't want to handle it, let me know, then I'll create a good-first-issue :)
I'll add a patch for `cast_lossless` -- the rest should probably go into an issue.
Tamir Duberstein (6): rust: retain pointer mut-ness in `container_of!` rust: enable `clippy::ptr_as_ptr` lint rust: enable `clippy::ptr_cast_constness` lint rust: enable `clippy::as_ptr_cast_mut` lint rust: enable `clippy::as_underscore` lint rust: use strict provenance APIs
Makefile | 4 ++ init/Kconfig | 3 + rust/bindings/lib.rs | 1 + rust/kernel/alloc.rs | 2 +- rust/kernel/alloc/allocator_test.rs | 2 +- rust/kernel/alloc/kvec.rs | 4 +- rust/kernel/block/mq/operations.rs | 2 +- rust/kernel/block/mq/request.rs | 7 +- rust/kernel/device.rs | 5 +- rust/kernel/device_id.rs | 2 +- rust/kernel/devres.rs | 19 +++--- rust/kernel/error.rs | 2 +- rust/kernel/firmware.rs | 3 +- rust/kernel/fs/file.rs | 2 +- rust/kernel/io.rs | 16 ++--- rust/kernel/kunit.rs | 15 ++--- rust/kernel/lib.rs | 113 ++++++++++++++++++++++++++++++++- rust/kernel/list/impl_list_item_mod.rs | 2 +- rust/kernel/miscdevice.rs | 2 +- rust/kernel/of.rs | 6 +- rust/kernel/pci.rs | 15 +++-- rust/kernel/platform.rs | 6 +- rust/kernel/print.rs | 11 ++-- rust/kernel/rbtree.rs | 23 +++---- rust/kernel/seq_file.rs | 3 +- rust/kernel/str.rs | 18 ++---- rust/kernel/sync/poll.rs | 2 +- rust/kernel/uaccess.rs | 12 ++-- rust/kernel/workqueue.rs | 12 ++-- rust/uapi/lib.rs | 1 + 30 files changed, 218 insertions(+), 97 deletions(-)
base-commit: 498f7ee4773f22924f00630136da8575f38954e8
Btw I didn't find this commit anywhere I usually check, where is it from?
It was probably nowhere, a local frankenstein that included some fixes from rust-fixes.