Merge pull request torvalds#669 from ojeda/printk

rust: kernel: support `!CONFIG_PRINTK`

Author: ojeda

rust/kernel/device.rs

@@ -8,7 +8,7 @@
 use crate::{clk::Clk, error::from_kernel_err_ptr};
 
 use crate::{
-    bindings, c_str, c_types,
+    bindings,
     revocable::{Revocable, RevocableGuard},
     str::CStr,
     sync::{NeedsLockClass, RevocableMutex, RevocableMutexGuard, UniqueRef},
@@ -20,6 +20,9 @@ use core::{
     pin::Pin,
 };
 
+#[cfg(CONFIG_PRINTK)]
+use crate::{c_str, c_types};
+
 /// A raw device.
 ///
 /// # Safety
@@ -138,10 +141,12 @@ pub unsafe trait RawDevice {
     ///
     /// Callers must ensure that `klevel` is null-terminated; in particular, one of the
     /// `KERN_*`constants, for example, `KERN_CRIT`, `KERN_ALERT`, etc.
+    #[cfg_attr(not(CONFIG_PRINTK), allow(unused_variables))]
     unsafe fn printk(&self, klevel: &[u8], msg: fmt::Arguments<'_>) {
         // SAFETY: `klevel` is null-terminated and one of the kernel constants. `self.raw_device`
         // is valid because `self` is valid. The "%pA" format string expects a pointer to
         // `fmt::Arguments`, which is what we're passing as the last argument.
+        #[cfg(CONFIG_PRINTK)]
         unsafe {
             bindings::_dev_printk(
                 klevel as *const _ as *const c_types::c_char,

rust/kernel/print.rs

@@ -8,8 +8,13 @@
 
 use core::fmt;
 
-use crate::c_types::{c_char, c_void};
-use crate::{bindings, str::Formatter};
+use crate::{
+    c_types::{c_char, c_void},
+    str::Formatter,
+};
+
+#[cfg(CONFIG_PRINTK)]
+use crate::bindings;
 
 // Called from `vsprintf` with format specifier `%pA`.
 #[no_mangle]
@@ -93,12 +98,14 @@ pub mod format_strings {
 ///
 /// [`_printk`]: ../../../../include/linux/_printk.h
 #[doc(hidden)]
+#[cfg_attr(not(CONFIG_PRINTK), allow(unused_variables))]
 pub unsafe fn call_printk(
     format_string: &[u8; format_strings::LENGTH],
     module_name: &[u8],
     args: fmt::Arguments<'_>,
 ) {
     // `_printk` does not seem to fail in any path.
+    #[cfg(CONFIG_PRINTK)]
     unsafe {
         bindings::_printk(
             format_string.as_ptr() as _,
@@ -114,10 +121,12 @@ pub unsafe fn call_printk(
 ///
 /// [`_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 _,