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    Subject[PATCH v2 03/28] rust: print: add `pr_cont!` macro
    Date
    From: Miguel Ojeda <ojeda@kernel.org>

    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>
    Reviewed-by: Wei Liu <wei.liu@kernel.org>
    Reviewed-by: Sergio González Collado <sergio.collado@gmail.com>
    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
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