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Message-Id: <20250325-feat-add-bitmask-macro-v2-1-d3beabdad90f@gmail.com>
Date: Tue, 25 Mar 2025 10:10:25 -0300
From: Filipe Xavier <felipeaggger@...il.com>
To: Miguel Ojeda <ojeda@...nel.org>, Alex Gaynor <alex.gaynor@...il.com>,
Boqun Feng <boqun.feng@...il.com>, Gary Guo <gary@...yguo.net>,
Björn Roy Baron <bjorn3_gh@...tonmail.com>,
Benno Lossin <benno.lossin@...ton.me>,
Andreas Hindborg <a.hindborg@...nel.org>, Alice Ryhl <aliceryhl@...gle.com>,
Trevor Gross <tmgross@...ch.edu>, Danilo Krummrich <dakr@...nel.org>
Cc: daniel.almeida@...labora.com, rust-for-linux@...r.kernel.org,
felipe_life@...e.com, linux-kernel@...r.kernel.org,
Filipe Xavier <felipeaggger@...il.com>, Lyude Paul <lyude@...hat.com>
Subject: [PATCH v2] rust: add new macro for common bitmap operations
We have seen a proliferation of mod_whatever::foo::Flags
being defined with essentially the same implementation
for BitAnd, BitOr, contains and etc.
This macro aims to bring a solution for this,
allowing to generate these methods for user-defined structs.
With some use cases in KMS and VideoCodecs.
Small use sample:
`
const READ: Permission = Permission(1 << 0);
const WRITE: Permission = Permission(1 << 1);
impl_flags!(Permissions, Permission, u32);
let read_write = Permissions::from(READ) | WRITE;
let read_only = read_write & READ;
`
Link: https://rust-for-linux.zulipchat.com/#narrow/channel/288089-General/topic/We.20really.20need.20a.20common.20.60Flags.60.20type
Signed-off-by: Filipe Xavier <felipeaggger@...il.com>
Suggested-by: Daniel Almeida <daniel.almeida@...labora.com>
Suggested-by: Lyude Paul <lyude@...hat.com>
---
Changes in v2:
- rename: change macro and file name to impl_flags.
- negation sign: change char for negation to `!`.
- transpose docs: add support to transpose user provided docs.
- visibility: add support to use user defined visibility.
- operations: add new operations for flag,
to support use between bit and bitmap, eg: flag & flags.
- code style: small fixes to remove warnings.
- Link to v1: https://lore.kernel.org/r/20250304-feat-add-bitmask-macro-v1-1-1c2d2bcb476b@gmail.com
---
rust/kernel/impl_flags.rs | 214 ++++++++++++++++++++++++++++++++++++++++++++++
rust/kernel/lib.rs | 1 +
rust/kernel/prelude.rs | 1 +
3 files changed, 216 insertions(+)
diff --git a/rust/kernel/impl_flags.rs b/rust/kernel/impl_flags.rs
new file mode 100644
index 0000000000000000000000000000000000000000..e7cf00e14bdcd2acea47b8c158a984ac0206568b
--- /dev/null
+++ b/rust/kernel/impl_flags.rs
@@ -0,0 +1,214 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! impl_flags utilities for working with flags.
+
+/// Declares a impl_flags type with its corresponding flag type.
+///
+/// This macro generates:
+/// - Implementations of common bitmask operations ([`BitOr`], [`BitAnd`], etc.).
+/// - Utility methods such as `.contains()` to check flags.
+///
+/// # Examples
+///
+/// Defining and using impl_flags:
+///
+/// ```
+/// impl_flags!(
+/// /// Represents multiple permissions.
+/// pub Permissions,
+/// /// Represents a single permission.
+/// pub Permission,
+/// u32
+/// );
+///
+/// // Define some individual permissions.
+/// const READ: Permission = Permission(1 << 0);
+/// const WRITE: Permission = Permission(1 << 1);
+/// const EXECUTE: Permission = Permission(1 << 2);
+///
+/// // Combine multiple permissions using operation OR (`|`).
+/// let read_write = Permissions::from(READ) | WRITE;
+///
+/// assert!(read_write.contains(READ));
+/// assert!(read_write.contains(WRITE));
+/// assert!(!read_write.contains(EXECUTE));
+///
+/// // Removing a permission with operation AND (`&`).
+/// let read_only = read_write & READ;
+/// assert!(read_only.contains(READ));
+/// assert!(!read_only.contains(WRITE));
+///
+/// // Toggling permissions with XOR (`^`).
+/// let toggled = read_only ^ Permissions::from(READ);
+/// assert!(!toggled.contains(READ));
+///
+/// // Inverting permissions with negation (`!`).
+/// let negated = !read_only;
+/// assert!(negated.contains(WRITE));
+/// ```
+#[macro_export]
+macro_rules! impl_flags {
+ (
+ $(#[$outer_flags:meta])* $vis_flags:vis $flags:ident,
+ $(#[$outer_flag:meta])* $vis_flag:vis $flag:ident,
+ $ty:ty
+ ) => {
+ $(#[$outer_flags])*
+ #[repr(transparent)]
+ #[derive(Copy, Clone, Default, PartialEq, Eq)]
+ $vis_flags struct $flags($ty);
+
+ $(#[$outer_flag])*
+ #[derive(Copy, Clone, PartialEq, Eq)]
+ $vis_flag struct $flag($ty);
+
+ impl From<$flag> for $flags {
+ #[inline]
+ fn from(value: $flag) -> Self {
+ Self(value.0)
+ }
+ }
+
+ impl From<$flags> for $ty {
+ #[inline]
+ fn from(value: $flags) -> Self {
+ value.0
+ }
+ }
+
+ impl core::ops::BitOr for $flags {
+ type Output = Self;
+
+ #[inline]
+ fn bitor(self, rhs: Self) -> Self::Output {
+ Self(self.0 | rhs.0)
+ }
+ }
+
+ impl core::ops::BitOrAssign for $flags {
+ #[inline]
+ fn bitor_assign(&mut self, rhs: Self) {
+ *self = *self | rhs;
+ }
+ }
+
+ impl core::ops::BitAnd for $flags {
+ type Output = Self;
+
+ #[inline]
+ fn bitand(self, rhs: Self) -> Self::Output {
+ Self(self.0 & rhs.0)
+ }
+ }
+
+ impl core::ops::BitAndAssign for $flags {
+ #[inline]
+ fn bitand_assign(&mut self, rhs: Self) {
+ *self = *self & rhs;
+ }
+ }
+
+ impl core::ops::BitOr<$flag> for $flags {
+ type Output = Self;
+
+ #[inline]
+ fn bitor(self, rhs: $flag) -> Self::Output {
+ self | Self::from(rhs)
+ }
+ }
+
+ impl core::ops::BitOrAssign<$flag> for $flags {
+ #[inline]
+ fn bitor_assign(&mut self, rhs: $flag) {
+ *self = *self | rhs;
+ }
+ }
+
+ impl core::ops::BitAnd<$flag> for $flags {
+ type Output = Self;
+
+ #[inline]
+ fn bitand(self, rhs: $flag) -> Self::Output {
+ self & Self::from(rhs)
+ }
+ }
+
+ impl core::ops::BitAndAssign<$flag> for $flags {
+ #[inline]
+ fn bitand_assign(&mut self, rhs: $flag) {
+ *self = *self & rhs;
+ }
+ }
+
+ impl core::ops::BitXor for $flags {
+ type Output = Self;
+
+ #[inline]
+ fn bitxor(self, rhs: Self) -> Self::Output {
+ Self(self.0 ^ rhs.0)
+ }
+ }
+
+ impl core::ops::BitXorAssign for $flags {
+ #[inline]
+ fn bitxor_assign(&mut self, rhs: Self) {
+ *self = *self ^ rhs;
+ }
+ }
+
+ impl core::ops::Not for $flags {
+ type Output = Self;
+
+ #[inline]
+ fn not(self) -> Self::Output {
+ Self(!self.0)
+ }
+ }
+
+ impl core::ops::BitOr for $flag {
+ type Output = $flags;
+ #[inline]
+ fn bitor(self, rhs: Self) -> Self::Output {
+ $flags(self.0 | rhs.0)
+ }
+ }
+
+ impl core::ops::BitAnd for $flag {
+ type Output = $flags;
+ #[inline]
+ fn bitand(self, rhs: Self) -> Self::Output {
+ $flags(self.0 & rhs.0)
+ }
+ }
+
+ impl core::ops::BitXor for $flag {
+ type Output = $flags;
+ #[inline]
+ fn bitxor(self, rhs: Self) -> Self::Output {
+ $flags(self.0 ^ rhs.0)
+ }
+ }
+
+ impl core::ops::Not for $flag {
+ type Output = $flags;
+ #[inline]
+ fn not(self) -> Self::Output {
+ $flags(!self.0)
+ }
+ }
+
+ impl $flags {
+ /// Returns an empty instance of `type` where no flags are set.
+ #[inline]
+ pub const fn empty() -> Self {
+ Self(0)
+ }
+
+ /// Checks if a specific flag is set.
+ #[inline]
+ pub fn contains(self, flag: $flag) -> bool {
+ (self.0 & flag.0) == flag.0
+ }
+ }
+ };
+}
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index 496ed32b0911a9fdbce5d26738b9cf7ef910b269..7653485a456ae5aa51becbf04153ea54a7067d9e 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -49,6 +49,7 @@
#[cfg(CONFIG_RUST_FW_LOADER_ABSTRACTIONS)]
pub mod firmware;
pub mod fs;
+pub mod impl_flags;
pub mod init;
pub mod io;
pub mod ioctl;
diff --git a/rust/kernel/prelude.rs b/rust/kernel/prelude.rs
index dde2e0649790ca24e6c347b29465ea0a1c3e503b..0f691dd2df71d821265fae01555ba50e6a76f372 100644
--- a/rust/kernel/prelude.rs
+++ b/rust/kernel/prelude.rs
@@ -25,6 +25,7 @@
#[doc(no_inline)]
pub use super::dbg;
pub use super::fmt;
+pub use super::impl_flags;
pub use super::{dev_alert, dev_crit, dev_dbg, dev_emerg, dev_err, dev_info, dev_notice, dev_warn};
pub use super::{pr_alert, pr_crit, pr_debug, pr_emerg, pr_err, pr_info, pr_notice, pr_warn};
---
base-commit: beeb78d46249cab8b2b8359a2ce8fa5376b5ad2d
change-id: 20250304-feat-add-bitmask-macro-6424b1c317e2
Best regards,
--
Filipe Xavier <felipeaggger@...il.com>
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