Merge tag 'rust-6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux

Pull Rust updates from Miguel Ojeda:
 "Toolchain and infrastructure:

   - Enable a set of Clippy lints: 'ptr_as_ptr', 'ptr_cast_constness',
     'as_ptr_cast_mut', 'as_underscore', 'cast_lossless' and
     'ref_as_ptr'

     These are intended to avoid type casts with the 'as' operator,
     which are quite powerful, into restricted variants that are less
     powerful and thus should help to avoid mistakes

   - Remove the 'author' key now that most instances were moved to the
     plural one in the previous cycle

  'kernel' crate:

   - New 'bug' module: add 'warn_on!' macro which reuses the existing
     'BUG'/'WARN' infrastructure, i.e. it respects the usual sysctls and
     kernel parameters:

         warn_on!(value == 42);

     To avoid duplicating the assembly code, the same strategy is
     followed as for the static branch code in order to share the
     assembly between both C and Rust

     This required a few rearrangements on C arch headers -- the
     existing C macros should still generate the same outputs, thus no
     functional change expected there

   - 'workqueue' module: add delayed work items, including a
     'DelayedWork' struct, a 'impl_has_delayed_work!' macro and an
     'enqueue_delayed' method, e.g.:

         /// Enqueue the struct for execution on the system workqueue,
         /// where its value will be printed 42 jiffies later.
         fn print_later(value: Arc<MyStruct>) {
             let _ = workqueue::system().enqueue_delayed(value, 42);
         }

   - New 'bits' module: add support for 'bit' and 'genmask' functions,
     with runtime- and compile-time variants, e.g.:

         static_assert!(0b00010000 == bit_u8(4));
         static_assert!(0b00011110 == genmask_u8(1..=4));

         assert!(checked_bit_u32(u32::BITS).is_none());

   - 'uaccess' module: add 'UserSliceReader::strcpy_into_buf', which
     reads NUL-terminated strings from userspace into a '&CStr'

     Introduce 'UserPtr' newtype, similar in purpose to '__user' in C,
     to minimize mistakes handling userspace pointers, including mixing
     them up with integers and leaking them via the 'Debug' trait. Add
     it to the prelude, too

   - Start preparations for the replacement of our custom 'CStr' type
     with the analogous type in the 'core' standard library. This will
     take place across several cycles to make it easier. For this one,
     it includes a new 'fmt' module, using upstream method names and
     some other cleanups

     Replace 'fmt!' with a re-export, which helps Clippy lint properly,
     and clean up the found 'uninlined-format-args' instances

   - 'dma' module:

      - Clarify wording and be consistent in 'coherent' nomenclature

      - Convert the 'read!()' and 'write!()' macros to return a 'Result'

      - Add 'as_slice()', 'write()' methods in 'CoherentAllocation'

      - Expose 'count()' and 'size()' in 'CoherentAllocation' and add
        the corresponding type invariants

      - Implement 'CoherentAllocation::dma_handle_with_offset()'

   - 'time' module:

      - Make 'Instant' generic over clock source. This allows the
        compiler to assert that arithmetic expressions involving the
        'Instant' use 'Instants' based on the same clock source

      - Make 'HrTimer' generic over the timer mode. 'HrTimer' timers
        take a 'Duration' or an 'Instant' when setting the expiry time,
        depending on the timer mode. With this change, the compiler can
        check the type matches the timer mode

      - Add an abstraction for 'fsleep'. 'fsleep' is a flexible sleep
        function that will select an appropriate sleep method depending
        on the requested sleep time

      - Avoid 64-bit divisions on 32-bit hardware when calculating
        timestamps

      - Seal the 'HrTimerMode' trait. This prevents users of the
        'HrTimerMode' from implementing the trait on their own types

      - Pass the correct timer mode ID to 'hrtimer_start_range_ns()'

   - 'list' module: remove 'OFFSET' constants, allowing to remove
     pointer arithmetic; now 'impl_list_item!' invokes
     'impl_has_list_links!' or 'impl_has_list_links_self_ptr!'. Other
     simplifications too

   - 'types' module: remove 'ForeignOwnable::PointedTo' in favor of a
     constant, which avoids exposing the type of the opaque pointer, and
     require 'into_foreign' to return non-null

     Remove the 'Either<L, R>' type as well. It is unused, and we want
     to encourage the use of custom enums for concrete use cases

   - 'sync' module: implement 'Borrow' and 'BorrowMut' for 'Arc' types
     to allow them to be used in generic APIs

   - 'alloc' module: implement 'Borrow' and 'BorrowMut' for 'Box<T, A>';
     and 'Borrow', 'BorrowMut' and 'Default' for 'Vec<T, A>'

   - 'Opaque' type: add 'cast_from' method to perform a restricted cast
     that cannot change the inner type and use it in callers of
     'container_of!'. Rename 'raw_get' to 'cast_into' to match it

   - 'rbtree' module: add 'is_empty' method

   - 'sync' module: new 'aref' submodule to hold 'AlwaysRefCounted' and
     'ARef', which are moved from the too general 'types' module which
     we want to reduce or eventually remove. Also fix a safety comment
     in 'static_lock_class'

  'pin-init' crate:

   - Add 'impl<T, E> [Pin]Init<T, E> for Result<T, E>', so results are
     now (pin-)initializers

   - Add 'Zeroable::init_zeroed()' that delegates to 'init_zeroed()'

   - New 'zeroed()', a safe version of 'mem::zeroed()' and also provide
     it via 'Zeroable::zeroed()'

   - Implement 'Zeroable' for 'Option<&T>', 'Option<&mut T>' and for
     'Option<[unsafe] [extern "abi"] fn(...args...) -> ret>' for
     '"Rust"' and '"C"' ABIs and up to 20 arguments

   - Changed blanket impls of 'Init' and 'PinInit' from 'impl<T, E>
     [Pin]Init<T, E> for T' to 'impl<T> [Pin]Init<T> for T'

   - Renamed 'zeroed()' to 'init_zeroed()'

   - Upstream dev news: improve CI more to deny warnings, use
     '--all-targets'. Check the synchronization status of the two
     '-next' branches in upstream and the kernel

  MAINTAINERS:

   - Add Vlastimil Babka, Liam R. Howlett, Uladzislau Rezki and Lorenzo
     Stoakes as reviewers (thanks everyone)

  And a few other cleanups and improvements"

* tag 'rust-6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux: (76 commits)
  rust: Add warn_on macro
  arm64/bug: Add ARCH_WARN_ASM macro for BUG/WARN asm code sharing with Rust
  riscv/bug: Add ARCH_WARN_ASM macro for BUG/WARN asm code sharing with Rust
  x86/bug: Add ARCH_WARN_ASM macro for BUG/WARN asm code sharing with Rust
  rust: kernel: move ARef and AlwaysRefCounted to sync::aref
  rust: sync: fix safety comment for `static_lock_class`
  rust: types: remove `Either<L, R>`
  rust: kernel: use `core::ffi::CStr` method names
  rust: str: add `CStr` methods matching `core::ffi::CStr`
  rust: str: remove unnecessary qualification
  rust: use `kernel::{fmt,prelude::fmt!}`
  rust: kernel: add `fmt` module
  rust: kernel: remove `fmt!`, fix clippy::uninlined-format-args
  scripts: rust: emit path candidates in panic message
  scripts: rust: replace length checks with match
  rust: list: remove nonexistent generic parameter in link
  rust: bits: add support for bits/genmask macros
  rust: list: remove OFFSET constants
  rust: list: add `impl_list_item!` examples
  rust: list: use fully qualified path
  ...

1 files changed, 68 insertions, 43 deletions

diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs
index a927db8e079c..6c892550c0ba 100644
--- a/rust/kernel/str.rs
+++ b/rust/kernel/str.rs
@@ -3,7 +3,7 @@
 //! String representations.
 
 use crate::alloc::{flags::*, AllocError, KVec};
-use core::fmt::{self, Write};
+use crate::fmt::{self, Write};
 use core::ops::{self, Deref, DerefMut, Index};
 
 use crate::prelude::*;
@@ -29,7 +29,7 @@ impl BStr {
     #[inline]
     pub const fn from_bytes(bytes: &[u8]) -> &Self {
         // SAFETY: `BStr` is transparent to `[u8]`.
-        unsafe { &*(bytes as *const [u8] as *const BStr) }
+        unsafe { &*(core::ptr::from_ref(bytes) as *const BStr) }
     }
 
     /// Strip a prefix from `self`. Delegates to [`slice::strip_prefix`].
@@ -54,14 +54,14 @@ impl fmt::Display for BStr {
     /// Formats printable ASCII characters, escaping the rest.
     ///
     /// ```
-    /// # use kernel::{fmt, b_str, str::{BStr, CString}};
+    /// # use kernel::{prelude::fmt, b_str, str::{BStr, CString}};
     /// let ascii = b_str!("Hello, BStr!");
-    /// let s = CString::try_from_fmt(fmt!("{}", ascii))?;
-    /// assert_eq!(s.as_bytes(), "Hello, BStr!".as_bytes());
+    /// let s = CString::try_from_fmt(fmt!("{ascii}"))?;
+    /// assert_eq!(s.to_bytes(), "Hello, BStr!".as_bytes());
     ///
     /// let non_ascii = b_str!("🦀");
-    /// let s = CString::try_from_fmt(fmt!("{}", non_ascii))?;
-    /// assert_eq!(s.as_bytes(), "\\xf0\\x9f\\xa6\\x80".as_bytes());
+    /// let s = CString::try_from_fmt(fmt!("{non_ascii}"))?;
+    /// assert_eq!(s.to_bytes(), "\\xf0\\x9f\\xa6\\x80".as_bytes());
     /// # Ok::<(), kernel::error::Error>(())
     /// ```
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
@@ -85,15 +85,15 @@ impl fmt::Debug for BStr {
     /// escaping the rest.
     ///
     /// ```
-    /// # use kernel::{fmt, b_str, str::{BStr, CString}};
+    /// # use kernel::{prelude::fmt, b_str, str::{BStr, CString}};
     /// // Embedded double quotes are escaped.
     /// let ascii = b_str!("Hello, \"BStr\"!");
-    /// let s = CString::try_from_fmt(fmt!("{:?}", ascii))?;
-    /// assert_eq!(s.as_bytes(), "\"Hello, \\\"BStr\\\"!\"".as_bytes());
+    /// let s = CString::try_from_fmt(fmt!("{ascii:?}"))?;
+    /// assert_eq!(s.to_bytes(), "\"Hello, \\\"BStr\\\"!\"".as_bytes());
     ///
     /// let non_ascii = b_str!("😺");
-    /// let s = CString::try_from_fmt(fmt!("{:?}", non_ascii))?;
-    /// assert_eq!(s.as_bytes(), "\"\\xf0\\x9f\\x98\\xba\"".as_bytes());
+    /// let s = CString::try_from_fmt(fmt!("{non_ascii:?}"))?;
+    /// assert_eq!(s.to_bytes(), "\"\\xf0\\x9f\\x98\\xba\"".as_bytes());
     /// # Ok::<(), kernel::error::Error>(())
     /// ```
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
@@ -175,6 +175,15 @@ macro_rules! b_str {
     }};
 }
 
+/// Returns a C pointer to the string.
+// It is a free function rather than a method on an extension trait because:
+//
+// - error[E0379]: functions in trait impls cannot be declared const
+#[inline]
+pub const fn as_char_ptr_in_const_context(c_str: &CStr) -> *const c_char {
+    c_str.0.as_ptr()
+}
+
 /// Possible errors when using conversion functions in [`CStr`].
 #[derive(Debug, Clone, Copy)]
 pub enum CStrConvertError {
@@ -232,12 +241,12 @@ impl CStr {
     /// last at least `'a`. When `CStr` is alive, the memory pointed by `ptr`
     /// must not be mutated.
     #[inline]
-    pub unsafe fn from_char_ptr<'a>(ptr: *const crate::ffi::c_char) -> &'a Self {
+    pub unsafe fn from_char_ptr<'a>(ptr: *const c_char) -> &'a Self {
         // SAFETY: The safety precondition guarantees `ptr` is a valid pointer
         // to a `NUL`-terminated C string.
         let len = unsafe { bindings::strlen(ptr) } + 1;
         // SAFETY: Lifetime guaranteed by the safety precondition.
-        let bytes = unsafe { core::slice::from_raw_parts(ptr as _, len) };
+        let bytes = unsafe { core::slice::from_raw_parts(ptr.cast(), len) };
         // SAFETY: As `len` is returned by `strlen`, `bytes` does not contain interior `NUL`.
         // As we have added 1 to `len`, the last byte is known to be `NUL`.
         unsafe { Self::from_bytes_with_nul_unchecked(bytes) }
@@ -290,27 +299,49 @@ impl CStr {
     #[inline]
     pub unsafe fn from_bytes_with_nul_unchecked_mut(bytes: &mut [u8]) -> &mut CStr {
         // SAFETY: Properties of `bytes` guaranteed by the safety precondition.
-        unsafe { &mut *(bytes as *mut [u8] as *mut CStr) }
+        unsafe { &mut *(core::ptr::from_mut(bytes) as *mut CStr) }
     }
 
     /// Returns a C pointer to the string.
+    ///
+    /// Using this function in a const context is deprecated in favor of
+    /// [`as_char_ptr_in_const_context`] in preparation for replacing `CStr` with `core::ffi::CStr`
+    /// which does not have this method.
     #[inline]
-    pub const fn as_char_ptr(&self) -> *const crate::ffi::c_char {
-        self.0.as_ptr()
+    pub const fn as_char_ptr(&self) -> *const c_char {
+        as_char_ptr_in_const_context(self)
     }
 
     /// Convert the string to a byte slice without the trailing `NUL` byte.
     #[inline]
-    pub fn as_bytes(&self) -> &[u8] {
+    pub fn to_bytes(&self) -> &[u8] {
         &self.0[..self.len()]
     }
 
+    /// Convert the string to a byte slice without the trailing `NUL` byte.
+    ///
+    /// This function is deprecated in favor of [`Self::to_bytes`] in preparation for replacing
+    /// `CStr` with `core::ffi::CStr` which does not have this method.
+    #[inline]
+    pub fn as_bytes(&self) -> &[u8] {
+        self.to_bytes()
+    }
+
     /// Convert the string to a byte slice containing the trailing `NUL` byte.
     #[inline]
-    pub const fn as_bytes_with_nul(&self) -> &[u8] {
+    pub const fn to_bytes_with_nul(&self) -> &[u8] {
         &self.0
     }
 
+    /// Convert the string to a byte slice containing the trailing `NUL` byte.
+    ///
+    /// This function is deprecated in favor of [`Self::to_bytes_with_nul`] in preparation for
+    /// replacing `CStr` with `core::ffi::CStr` which does not have this method.
+    #[inline]
+    pub const fn as_bytes_with_nul(&self) -> &[u8] {
+        self.to_bytes_with_nul()
+    }
+
     /// Yields a [`&str`] slice if the [`CStr`] contains valid UTF-8.
     ///
     /// If the contents of the [`CStr`] are valid UTF-8 data, this
@@ -429,20 +460,20 @@ impl fmt::Display for CStr {
     ///
     /// ```
     /// # use kernel::c_str;
-    /// # use kernel::fmt;
+    /// # use kernel::prelude::fmt;
     /// # use kernel::str::CStr;
     /// # use kernel::str::CString;
     /// let penguin = c_str!("🐧");
-    /// let s = CString::try_from_fmt(fmt!("{}", penguin))?;
-    /// assert_eq!(s.as_bytes_with_nul(), "\\xf0\\x9f\\x90\\xa7\0".as_bytes());
+    /// let s = CString::try_from_fmt(fmt!("{penguin}"))?;
+    /// assert_eq!(s.to_bytes_with_nul(), "\\xf0\\x9f\\x90\\xa7\0".as_bytes());
     ///
     /// let ascii = c_str!("so \"cool\"");
-    /// let s = CString::try_from_fmt(fmt!("{}", ascii))?;
-    /// assert_eq!(s.as_bytes_with_nul(), "so \"cool\"\0".as_bytes());
+    /// let s = CString::try_from_fmt(fmt!("{ascii}"))?;
+    /// assert_eq!(s.to_bytes_with_nul(), "so \"cool\"\0".as_bytes());
     /// # Ok::<(), kernel::error::Error>(())
     /// ```
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        for &c in self.as_bytes() {
+        for &c in self.to_bytes() {
             if (0x20..0x7f).contains(&c) {
                 // Printable character.
                 f.write_char(c as char)?;
@@ -459,16 +490,16 @@ impl fmt::Debug for CStr {
     ///
     /// ```
     /// # use kernel::c_str;
-    /// # use kernel::fmt;
+    /// # use kernel::prelude::fmt;
     /// # use kernel::str::CStr;
     /// # use kernel::str::CString;
     /// let penguin = c_str!("🐧");
-    /// let s = CString::try_from_fmt(fmt!("{:?}", penguin))?;
+    /// let s = CString::try_from_fmt(fmt!("{penguin:?}"))?;
     /// assert_eq!(s.as_bytes_with_nul(), "\"\\xf0\\x9f\\x90\\xa7\"\0".as_bytes());
     ///
     /// // Embedded double quotes are escaped.
     /// let ascii = c_str!("so \"cool\"");
-    /// let s = CString::try_from_fmt(fmt!("{:?}", ascii))?;
+    /// let s = CString::try_from_fmt(fmt!("{ascii:?}"))?;
     /// assert_eq!(s.as_bytes_with_nul(), "\"so \\\"cool\\\"\"\0".as_bytes());
     /// # Ok::<(), kernel::error::Error>(())
     /// ```
@@ -578,7 +609,7 @@ mod tests {
 
     macro_rules! format {
         ($($f:tt)*) => ({
-            CString::try_from_fmt(::kernel::fmt!($($f)*))?.to_str()?
+            CString::try_from_fmt(fmt!($($f)*))?.to_str()?
         })
     }
 
@@ -728,9 +759,9 @@ impl RawFormatter {
     pub(crate) unsafe fn from_ptrs(pos: *mut u8, end: *mut u8) -> Self {
         // INVARIANT: The safety requirements guarantee the type invariants.
         Self {
-            beg: pos as _,
-            pos: pos as _,
-            end: end as _,
+            beg: pos as usize,
+            pos: pos as usize,
+            end: end as usize,
         }
     }
 
@@ -755,7 +786,7 @@ impl RawFormatter {
     ///
     /// N.B. It may point to invalid memory.
     pub(crate) fn pos(&self) -> *mut u8 {
-        self.pos as _
+        self.pos as *mut u8
     }
 
     /// Returns the number of bytes written to the formatter.
@@ -840,14 +871,14 @@ impl fmt::Write for Formatter {
 /// # Examples
 ///
 /// ```
-/// use kernel::{str::CString, fmt};
+/// use kernel::{str::CString, prelude::fmt};
 ///
 /// let s = CString::try_from_fmt(fmt!("{}{}{}", "abc", 10, 20))?;
-/// assert_eq!(s.as_bytes_with_nul(), "abc1020\0".as_bytes());
+/// assert_eq!(s.to_bytes_with_nul(), "abc1020\0".as_bytes());
 ///
 /// let tmp = "testing";
 /// let s = CString::try_from_fmt(fmt!("{tmp}{}", 123))?;
-/// assert_eq!(s.as_bytes_with_nul(), "testing123\0".as_bytes());
+/// assert_eq!(s.to_bytes_with_nul(), "testing123\0".as_bytes());
 ///
 /// // This fails because it has an embedded `NUL` byte.
 /// let s = CString::try_from_fmt(fmt!("a\0b{}", 123));
@@ -917,7 +948,7 @@ impl<'a> TryFrom<&'a CStr> for CString {
     fn try_from(cstr: &'a CStr) -> Result<CString, AllocError> {
         let mut buf = KVec::new();
 
-        buf.extend_from_slice(cstr.as_bytes_with_nul(), GFP_KERNEL)?;
+        buf.extend_from_slice(cstr.to_bytes_with_nul(), GFP_KERNEL)?;
 
         // INVARIANT: The `CStr` and `CString` types have the same invariants for
         // the string data, and we copied it over without changes.
@@ -930,9 +961,3 @@ impl fmt::Debug for CString {
         fmt::Debug::fmt(&**self, f)
     }
 }
-
-/// A convenience alias for [`core::format_args`].
-#[macro_export]
-macro_rules! fmt {
-    ($($f:tt)*) => ( ::core::format_args!($($f)*) )
-}