Merge tag 'rust-rustfmt' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux

Pull rustfmt fixes from Miguel Ojeda: "Rust 'rustfmt' cleanup 'rustfmt', by default, formats imports in a way that is prone to conflicts while merging and rebasing, since in some cases it condenses several items into the same line. Document in our guidelines that we will handle this for the moment with the trailing empty comment workaround and make the tree 'rustfmt'-clean again" * tag 'rust-rustfmt' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux: rust: bitmap: fix formatting rust: cpufreq: fix formatting rust: alloc: employ a trailing comment to keep vertical layout docs: rust: add section on imports formatting

Linus Torvalds committed 1 year ago

Commit 1c64efc2 parents 648937f 1f1d3e14 files · +83 −5Browse files

Unified · Split

4 files

Documentation/rust/coding-guidelines.rst +75 −0
rust/kernel/alloc/kvec.rs +1 −1
rust/kernel/bitmap.rs +6 −2
rust/kernel/cpufreq.rs +1 −2

Documentation/rust/coding-guidelines.rst+75−0

@@ -38,6 +38,81 @@ Like ``clang-format`` for the rest of the kernel, ``rustfmt`` works on · 37 unmodified lines
38	38	individual files, and does not require a kernel configuration. Sometimes it may
39	39	even work with broken code.
40	40
	41	+Imports
	42	+~~~~~~~
	43	+
	44	+``rustfmt``, by default, formats imports in a way that is prone to conflicts
	45	+while merging and rebasing, since in some cases it condenses several items into
	46	+the same line. For instance:
	47	+
	48	+.. code-block:: rust
	49	+
	50	+ // Do not use this style.
	51	+ use crate::{
	52	+ example1,
	53	+ example2::{example3, example4, example5},
	54	+ example6, example7,
	55	+ example8::example9,
	56	+ };
	57	+
	58	+Instead, the kernel uses a vertical layout that looks like this:
	59	+
	60	+.. code-block:: rust
	61	+
	62	+ use crate::{
	63	+ example1,
	64	+ example2::{
	65	+ example3,
	66	+ example4,
	67	+ example5, //
	68	+ },
	69	+ example6,
	70	+ example7,
	71	+ example8::example9, //
	72	+ };
	73	+
	74	+That is, each item goes into its own line, and braces are used as soon as there
	75	+is more than one item in a list.
	76	+
	77	+The trailing empty comment allows to preserve this formatting. Not only that,
	78	+``rustfmt`` will actually reformat imports vertically when the empty comment is
	79	+added. That is, it is possible to easily reformat the original example into the
	80	+expected style by running ``rustfmt`` on an input like:
	81	+
	82	+.. code-block:: rust
	83	+
	84	+ // Do not use this style.
	85	+ use crate::{
	86	+ example1,
	87	+ example2::{example3, example4, example5, //
	88	+ },
	89	+ example6, example7,
	90	+ example8::example9, //
	91	+ };
	92	+
	93	+The trailing empty comment works for nested imports, as shown above, as well as
	94	+for single item imports -- this can be useful to minimize diffs within patch
	95	+series:
	96	+
	97	+.. code-block:: rust
	98	+
	99	+ use crate::{
	100	+ example1, //
	101	+ };
	102	+
	103	+The trailing empty comment works in any of the lines within the braces, but it
	104	+is preferred to keep it in the last item, since it is reminiscent of the
	105	+trailing comma in other formatters. Sometimes it may be simpler to avoid moving
	106	+the comment several times within a patch series due to changes in the list.
	107	+
	108	+There may be cases where exceptions may need to be made, i.e. none of this is
	109	+a hard rule. There is also code that is not migrated to this style yet, but
	110	+please do not introduce code in other styles.
	111	+
	112	+Eventually, the goal is to get ``rustfmt`` to support this formatting style (or
	113	+a similar one) automatically in a stable release without requiring the trailing
	114	+empty comment. Thus, at some point, the goal is to remove those comments.
	115	+
41	116
42	117	Comments
43	118	--------

rust/kernel/alloc/kvec.rs+1−1

@@ -9,7 +9,7 @@ use super::{ · 8 unmodified lines
9	9	};
10	10	use crate::{
11	11	fmt,
12		− page::AsPageIter,
	12	+ page::AsPageIter, //
13	13	};
14	14	use core::{
15	15	borrow::{Borrow, BorrowMut},

rust/kernel/bitmap.rs+6−2

@@ -167,7 +167,9 @@ impl core::ops::Deref for BitmapVec { · 166 unmodified lines
167	167	let ptr = if self.nbits <= BITS_PER_LONG {
168	168	// SAFETY: Bitmap is represented inline.
169	169	#[allow(unused_unsafe, reason = "Safe since Rust 1.92.0")]
170		− unsafe { core::ptr::addr_of!(self.repr.bitmap) }
	170	+ unsafe {
	171	+ core::ptr::addr_of!(self.repr.bitmap)
	172	+ }
171	173	} else {
172	174	// SAFETY: Bitmap is represented as array of `unsigned long`.
173	175	unsafe { self.repr.ptr.as_ptr() }
@@ -184,7 +186,9 @@ impl core::ops::DerefMut for BitmapVec { · 10 unmodified lines
184	186	let ptr = if self.nbits <= BITS_PER_LONG {
185	187	// SAFETY: Bitmap is represented inline.
186	188	#[allow(unused_unsafe, reason = "Safe since Rust 1.92.0")]
187		− unsafe { core::ptr::addr_of_mut!(self.repr.bitmap) }
	189	+ unsafe {
	190	+ core::ptr::addr_of_mut!(self.repr.bitmap)
	191	+ }
188	192	} else {
189	193	// SAFETY: Bitmap is represented as array of `unsigned long`.
190	194	unsafe { self.repr.ptr.as_ptr() }

rust/kernel/cpufreq.rs+1−2

@@ -38,8 +38,7 @@ use macros::vtable; · 37 unmodified lines
38	38	const CPUFREQ_NAME_LEN: usize = bindings::CPUFREQ_NAME_LEN as usize;
39	39
40	40	/// Default transition latency value in nanoseconds.
41		−pub const DEFAULT_TRANSITION_LATENCY_NS: u32 =
42		− bindings::CPUFREQ_DEFAULT_TRANSITION_LATENCY_NS;
	41	+pub const DEFAULT_TRANSITION_LATENCY_NS: u32 = bindings::CPUFREQ_DEFAULT_TRANSITION_LATENCY_NS;
43	42
44	43	/// CPU frequency driver flags.
45	44	pub mod flags {