diff options
| -rw-r--r-- | rust/kernel/print.rs | 29 |
1 files changed, 18 insertions, 11 deletions
diff --git a/rust/kernel/print.rs b/rust/kernel/print.rs index 29bf9c2e8aee..30103325696d 100644 --- a/rust/kernel/print.rs +++ b/rust/kernel/print.rs @@ -142,17 +142,24 @@ pub fn call_printk_cont(args: fmt::Arguments<'_>) { macro_rules! print_macro ( // The non-continuation cases (most of them, e.g. `INFO`). ($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 - // by the `module!` proc macro or fixed values defined in a kernel - // crate. - unsafe { - $crate::print::call_printk( - &$format_string, - crate::__LOG_PREFIX, - format_args!($($arg)+), - ); + // To remain sound, `arg`s must be expanded outside the `unsafe` block. + // Typically one would use a `let` binding for that; however, `format_args!` + // takes borrows on the arguments, but does not extend the scope of temporaries. + // Therefore, a `match` expression is used to keep them around, since + // the scrutinee is kept until the end of the `match`. + match format_args!($($arg)+) { + // 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 + // by the `module!` proc macro or fixed values defined in a kernel + // crate. + args => unsafe { + $crate::print::call_printk( + &$format_string, + crate::__LOG_PREFIX, + args, + ); + } } ); |