rust: configfs: replace kernel::c_str! with C-Strings

C-String literals were added in Rust 1.77. Replace instances of
`kernel::c_str!` with C-String literals where possible.

Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Benno Lossin <lossin@kernel.org>
Signed-off-by: Tamir Duberstein <tamird@gmail.com>
Acked-by: Andreas Hindborg <a.hindborg@kernel.org>
Link: https://lore.kernel.org/r/20251222-cstr-configfs-v1-1-cc1665c51c43@gmail.com
Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>

Author: tamird

rust/kernel/configfs.rs

@@ -21,7 +21,6 @@
 //!
 //! ```ignore
 //! use kernel::alloc::flags;
-//! use kernel::c_str;
 //! use kernel::configfs_attrs;
 //! use kernel::configfs;
 //! use kernel::new_mutex;
@@ -50,7 +49,7 @@
 //!
 //!         try_pin_init!(Self {
 //!             config <- configfs::Subsystem::new(
-//!                 c_str!("rust_configfs"), item_type, Configuration::new()
+//!                 c"rust_configfs", item_type, Configuration::new()
 //!             ),
 //!         })
 //!     }
@@ -66,7 +65,7 @@
 //! impl Configuration {
 //!     fn new() -> impl PinInit<Self, Error> {
 //!         try_pin_init!(Self {
-//!             message: c_str!("Hello World\n"),
+//!             message: c"Hello World\n",
 //!             bar <- new_mutex!((KBox::new([0; PAGE_SIZE], flags::GFP_KERNEL)?, 0)),
 //!         })
 //!     }
@@ -1000,7 +999,9 @@ macro_rules! configfs_attrs {
                     static [< $data:upper _ $name:upper _ATTR >]:
                         $crate::configfs::Attribute<$attr, $data, $data> =
                             unsafe {
-                                $crate::configfs::Attribute::new(c_str!(::core::stringify!($name)))
+                                $crate::configfs::Attribute::new(
+                                    $crate::c_str!(::core::stringify!($name)),
+                                )
                             };
                 )*
 

samples/rust/rust_configfs.rs

@@ -3,7 +3,6 @@
 //! Rust configfs sample.
 
 use kernel::alloc::flags;
-use kernel::c_str;
 use kernel::configfs;
 use kernel::configfs::configfs_attrs;
 use kernel::new_mutex;
@@ -35,7 +34,7 @@ struct Configuration {
 impl Configuration {
     fn new() -> impl PinInit<Self, Error> {
         try_pin_init!(Self {
-            message: c_str!("Hello World\n"),
+            message: c"Hello World\n",
             bar <- new_mutex!((KBox::new([0; PAGE_SIZE], flags::GFP_KERNEL)?, 0)),
         })
     }
@@ -61,7 +60,7 @@ impl kernel::InPlaceModule for RustConfigfs {
 
         try_pin_init!(Self {
             config <- configfs::Subsystem::new(
-                c_str!("rust_configfs"), item_type, Configuration::new()
+                c"rust_configfs", item_type, Configuration::new()
             ),
         })
     }