[PATCH v1] rust: Add pr_*_once macros

[FUJITA Tomonori <fujita.tomonori@gmail.com>]

Add Rust version of pr_[emerg|alert|crit|err|warn|notic|info]_once
functions, which print a message only once.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
---
 rust/kernel/print.rs | 92 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 92 insertions(+)

diff --git a/rust/kernel/print.rs b/rust/kernel/print.rs
index a28077a7cb30..57dbb45ba5c0 100644
--- a/rust/kernel/print.rs
+++ b/rust/kernel/print.rs
@@ -414,3 +414,95 @@ macro_rules! pr_cont (
         $crate::print_macro!($crate::print::format_strings::CONT, true, $($arg)*)
     )
 );
+
+/// Executes code only once if the condition is true.
+///
+/// Public but hidden since it should only be used from public macros.
+#[doc(hidden)]
+#[macro_export]
+macro_rules! do_once_lite_if (
+    ($condition:expr, $e:expr) => (
+        {
+            #[link_section = ".data.once"]
+            static ALREADY_DONE: core::sync::atomic::AtomicBool =
+                core::sync::atomic::AtomicBool::new(false);
+            let mut ret = false;
+
+            if $condition && !ALREADY_DONE.swap(true, core::sync::atomic::Ordering::Relaxed) {
+                $e;
+                ret = true;
+            }
+            ret
+        }
+    )
+);
+
+/// Prints an emergency-level message (level 0) only once.
+///
+/// Equivalent to the kernel's [`pr_emerg_once`] macro.
+#[macro_export]
+macro_rules! pr_emerg_once (
+    ($($arg:tt)*) => (
+        $crate::do_once_lite_if!(true, $crate::pr_emerg!($($arg)*))
+    )
+);
+
+/// Prints an alert-level message (level 1) only once.
+///
+/// Equivalent to the kernel's [`pr_alert_once`] macro.
+#[macro_export]
+macro_rules! pr_alert_once (
+    ($($arg:tt)*) => (
+        $crate::do_once_lite_if!(true, $crate::pr_alert!($($arg)*))
+    )
+);
+
+/// Prints a critical-level message (level 2) only once.
+///
+/// Equivalent to the kernel's [`pr_crit_once`] macro.
+#[macro_export]
+macro_rules! pr_crit_once (
+    ($($arg:tt)*) => (
+        $crate::do_once_lite_if!(true, $crate::pr_crit!($($arg)*))
+    )
+);
+
+/// Prints an error-level message (level 3) only once.
+///
+/// Equivalent to the kernel's [`pr_err_once`] macro.
+#[macro_export]
+macro_rules! pr_err_once (
+    ($($arg:tt)*) => (
+        $crate::do_once_lite_if!(true, $crate::pr_err!($($arg)*))
+    )
+);
+
+/// Prints a warning-level message (level 4) only once.
+///
+/// Equivalent to the kernel's [`pr_warn_once`] macro.
+#[macro_export]
+macro_rules! pr_warn_once (
+    ($($arg:tt)*) => (
+        $crate::do_once_lite_if!(true, $crate::pr_warn!($($arg)*))
+    )
+);
+
+/// Prints a notice-level message (level 5) only once.
+///
+/// Equivalent to the kernel's [`pr_notice_once`] macro.
+#[macro_export]
+macro_rules! pr_notice_once (
+    ($($arg:tt)*) => (
+        $crate::do_once_lite_if!(true, $crate::pr_notice!($($arg)*))
+    )
+);
+
+/// Prints an info-level message (level 6) only once.
+///
+/// Equivalent to the kernel's [`pr_info_once`] macro.
+#[macro_export]
+macro_rules! pr_info_once (
+    ($($arg:tt)*) => (
+        $crate::do_once_lite_if!(true, $crate::pr_info!($($arg)*))
+    )
+);

base-commit: ae7851c29747fa3765ecb722fe722117a346f988
-- 
2.43.0