Re: [PATCH v1 03/28] rust: print: add `pr_cont!` macro

Sergio González Collado
2022-11-14T20:12:17Z

On Thu, 10 Nov 2022 at 11:43, Miguel Ojeda <ojeda@kernel.org> wrote:
>
> This level is a bit different from the rest since it does not
> pass the module name to the `_printk()` call.
>
> Thus add a new parameter to the general `print_macro!` to
> handle it differently.
>
> Co-developed-by: Adam Bratschi-Kaye <ark.email@gmail.com>
> Signed-off-by: Adam Bratschi-Kaye <ark.email@gmail.com>
> Co-developed-by: Wedson Almeida Filho <wedsonaf@gmail.com>
> Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com>
> Co-developed-by: Gary Guo <gary@garyguo.net>
> Signed-off-by: Gary Guo <gary@garyguo.net>
> Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
> ---
> rust/kernel/print.rs | 72 ++++++++++++++++++++++++++++++++++++++------
> 1 file changed, 63 insertions(+), 9 deletions(-)
>
> diff --git a/rust/kernel/print.rs b/rust/kernel/print.rs
> index 694f51c6da5c..29bf9c2e8aee 100644
> --- a/rust/kernel/print.rs
> +++ b/rust/kernel/print.rs
> @@ -81,6 +81,7 @@ pub mod format_strings {
> pub static NOTICE: [u8; LENGTH] = generate(false, bindings::KERN_NOTICE);
> pub static INFO: [u8; LENGTH] = generate(false, bindings::KERN_INFO);
> pub static DEBUG: [u8; LENGTH] = generate(false, bindings::KERN_DEBUG);
> + pub static CONT: [u8; LENGTH] = generate(true, bindings::KERN_CONT);
> }
>
> /// Prints a message via the kernel's [`_printk`].
> @@ -111,6 +112,26 @@ pub unsafe fn call_printk(
> }
> }
>
> +/// Prints a message via the kernel's [`_printk`] for the `CONT` level.
> +///
> +/// Public but hidden since it should only be used from public macros.
> +///
> +/// [`_printk`]: ../../../../include/linux/printk.h
> +#[doc(hidden)]
> +#[cfg_attr(not(CONFIG_PRINTK), allow(unused_variables))]
> +pub fn call_printk_cont(args: fmt::Arguments<'_>) {
> + // `_printk` does not seem to fail in any path.
> + //
> + // SAFETY: The format string is fixed.
> + #[cfg(CONFIG_PRINTK)]
> + unsafe {
> + bindings::_printk(
> + format_strings::CONT.as_ptr() as _,
> + &args as *const _ as *const c_void,
> + );
> + }
> +}
> +
> /// Performs formatting and forwards the string to [`call_printk`].
> ///
> /// Public but hidden since it should only be used from public macros.
> @@ -120,7 +141,7 @@ pub unsafe fn call_printk(
> #[allow(clippy::crate_in_macro_def)]
> macro_rules! print_macro (
> // The non-continuation cases (most of them, e.g. `INFO`).
> - ($format_string:path, $($arg:tt)+) => (
> + ($format_string:path, false, $($arg:tt)+) => (
> // SAFETY: This hidden macro should only be called by the documented
> // printing macros which ensure the format string is one of the fixed
> // ones. All `__LOG_PREFIX`s are null-terminated as they are generated
> @@ -134,6 +155,13 @@ macro_rules! print_macro (
> );
> }
> );
> +
> + // The `CONT` case.
> + ($format_string:path, true, $($arg:tt)+) => (
> + $crate::print::call_printk_cont(
> + format_args!($($arg)+),
> + );
> + );
> );
>
> /// Stub for doctests
> @@ -174,7 +202,7 @@ macro_rules! print_macro (
> #[macro_export]
> macro_rules! pr_emerg (
> ($($arg:tt)*) => (
> - $crate::print_macro!($crate::print::format_strings::EMERG, $($arg)*)
> + $crate::print_macro!($crate::print::format_strings::EMERG, false, $($arg)*)
> )
> );
>
> @@ -198,7 +226,7 @@ macro_rules! pr_emerg (
> #[macro_export]
> macro_rules! pr_alert (
> ($($arg:tt)*) => (
> - $crate::print_macro!($crate::print::format_strings::ALERT, $($arg)*)
> + $crate::print_macro!($crate::print::format_strings::ALERT, false, $($arg)*)
> )
> );
>
> @@ -222,7 +250,7 @@ macro_rules! pr_alert (
> #[macro_export]
> macro_rules! pr_crit (
> ($($arg:tt)*) => (
> - $crate::print_macro!($crate::print::format_strings::CRIT, $($arg)*)
> + $crate::print_macro!($crate::print::format_strings::CRIT, false, $($arg)*)
> )
> );
>
> @@ -246,7 +274,7 @@ macro_rules! pr_crit (
> #[macro_export]
> macro_rules! pr_err (
> ($($arg:tt)*) => (
> - $crate::print_macro!($crate::print::format_strings::ERR, $($arg)*)
> + $crate::print_macro!($crate::print::format_strings::ERR, false, $($arg)*)
> )
> );
>
> @@ -270,7 +298,7 @@ macro_rules! pr_err (
> #[macro_export]
> macro_rules! pr_warn (
> ($($arg:tt)*) => (
> - $crate::print_macro!($crate::print::format_strings::WARNING, $($arg)*)
> + $crate::print_macro!($crate::print::format_strings::WARNING, false, $($arg)*)
> )
> );
>
> @@ -294,7 +322,7 @@ macro_rules! pr_warn (
> #[macro_export]
> macro_rules! pr_notice (
> ($($arg:tt)*) => (
> - $crate::print_macro!($crate::print::format_strings::NOTICE, $($arg)*)
> + $crate::print_macro!($crate::print::format_strings::NOTICE, false, $($arg)*)
> )
> );
>
> @@ -319,7 +347,7 @@ macro_rules! pr_notice (
> #[doc(alias = "print")]
> macro_rules! pr_info (
> ($($arg:tt)*) => (
> - $crate::print_macro!($crate::print::format_strings::INFO, $($arg)*)
> + $crate::print_macro!($crate::print::format_strings::INFO, false, $($arg)*)
> )
> );
>
> @@ -346,7 +374,33 @@ macro_rules! pr_info (
> macro_rules! pr_debug (
> ($($arg:tt)*) => (
> if cfg!(debug_assertions) {
> - $crate::print_macro!($crate::print::format_strings::DEBUG, $($arg)*)
> + $crate::print_macro!($crate::print::format_strings::DEBUG, false, $($arg)*)
> }
> )
> );
> +
> +/// Continues a previous log message in the same line.
> +///
> +/// Use only when continuing a previous `pr_*!` macro (e.g. [`pr_info!`]).
> +///
> +/// Equivalent to the kernel's [`pr_cont`] macro.
> +///
> +/// Mimics the interface of [`std::print!`]. See [`core::fmt`] and
> +/// `alloc::format!` for information about the formatting syntax.
> +///
> +/// [`pr_cont`]: https://www.kernel.org/doc/html/latest/core-api/printk-basics.html#c.pr_cont
> +/// [`std::print!`]: https://doc.rust-lang.org/std/macro.print.html
> +///
> +/// # Examples
> +///
> +/// ```
> +/// # use kernel::pr_cont;
> +/// pr_info!("hello");
> +/// pr_cont!(" {}\n", "there");
> +/// ```
> +#[macro_export]
> +macro_rules! pr_cont (
> + ($($arg:tt)*) => (
> + $crate::print_macro!($crate::print::format_strings::CONT, true, $($arg)*)
> + )
> +);
> --
> 2.38.1
>
Reviewed-by: Sergio González Collado <sergio.collado@gmail.com>