ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 281 insertions, 0 deletions

diff --git a/rust/zerocopy/src/deprecated.rs b/rust/zerocopy/src/deprecated.rs
new file mode 100644
index 000000000..59ddd35c7
--- /dev/null
+++ b/rust/zerocopy/src/deprecated.rs
@@ -0,0 +1,281 @@
+// SPDX-License-Identifier: (BSD-2-Clause OR Apache-2.0) OR MIT
+//
+// Copyright 2024 The Fuchsia Authors
+//
+// Licensed under the 2-Clause BSD License <LICENSE-BSD or
+// https://opensource.org/license/bsd-2-clause>, Apache License, Version 2.0
+// <LICENSE-APACHE or https://www.apache.org/licenses/LICENSE-2.0>, or the MIT
+// license <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your option.
+// This file may not be copied, modified, or distributed except according to
+// those terms.
+
+//! Deprecated items. These are kept separate so that they don't clutter up
+//! other modules.
+
+use super::*;
+
+impl<B, T> Ref<B, T>
+where
+    B: ByteSlice,
+    T: KnownLayout + Immutable + ?Sized,
+{
+    #[deprecated(since = "0.8.0", note = "renamed to `Ref::from_bytes`")]
+    #[doc(hidden)]
+    #[must_use = "has no side effects"]
+    #[inline(always)]
+    pub fn new(bytes: B) -> Option<Ref<B, T>> {
+        Self::from_bytes(bytes).ok()
+    }
+}
+
+impl<B, T> Ref<B, T>
+where
+    B: SplitByteSlice,
+    T: KnownLayout + Immutable + ?Sized,
+{
+    #[deprecated(since = "0.8.0", note = "renamed to `Ref::from_prefix`")]
+    #[doc(hidden)]
+    #[must_use = "has no side effects"]
+    #[inline(always)]
+    pub fn new_from_prefix(bytes: B) -> Option<(Ref<B, T>, B)> {
+        Self::from_prefix(bytes).ok()
+    }
+}
+
+impl<B, T> Ref<B, T>
+where
+    B: SplitByteSlice,
+    T: KnownLayout + Immutable + ?Sized,
+{
+    #[deprecated(since = "0.8.0", note = "renamed to `Ref::from_suffix`")]
+    #[doc(hidden)]
+    #[must_use = "has no side effects"]
+    #[inline(always)]
+    pub fn new_from_suffix(bytes: B) -> Option<(B, Ref<B, T>)> {
+        Self::from_suffix(bytes).ok()
+    }
+}
+
+impl<B, T> Ref<B, T>
+where
+    B: ByteSlice,
+    T: Unaligned + KnownLayout + Immutable + ?Sized,
+{
+    #[deprecated(
+        since = "0.8.0",
+        note = "use `Ref::from_bytes`; for `T: Unaligned`, the returned `CastError` implements `Into<SizeError>`"
+    )]
+    #[doc(hidden)]
+    #[must_use = "has no side effects"]
+    #[inline(always)]
+    pub fn new_unaligned(bytes: B) -> Option<Ref<B, T>> {
+        Self::from_bytes(bytes).ok()
+    }
+}
+
+impl<B, T> Ref<B, T>
+where
+    B: SplitByteSlice,
+    T: Unaligned + KnownLayout + Immutable + ?Sized,
+{
+    #[deprecated(
+        since = "0.8.0",
+        note = "use `Ref::from_prefix`; for `T: Unaligned`, the returned `CastError` implements `Into<SizeError>`"
+    )]
+    #[doc(hidden)]
+    #[must_use = "has no side effects"]
+    #[inline(always)]
+    pub fn new_unaligned_from_prefix(bytes: B) -> Option<(Ref<B, T>, B)> {
+        Self::from_prefix(bytes).ok()
+    }
+}
+
+impl<B, T> Ref<B, T>
+where
+    B: SplitByteSlice,
+    T: Unaligned + KnownLayout + Immutable + ?Sized,
+{
+    #[deprecated(
+        since = "0.8.0",
+        note = "use `Ref::from_suffix`; for `T: Unaligned`, the returned `CastError` implements `Into<SizeError>`"
+    )]
+    #[doc(hidden)]
+    #[must_use = "has no side effects"]
+    #[inline(always)]
+    pub fn new_unaligned_from_suffix(bytes: B) -> Option<(B, Ref<B, T>)> {
+        Self::from_suffix(bytes).ok()
+    }
+}
+
+impl<B, T> Ref<B, [T]>
+where
+    B: ByteSlice,
+    T: Immutable,
+{
+    #[deprecated(since = "0.8.0", note = "`Ref::from_bytes` now supports slices")]
+    #[doc(hidden)]
+    #[inline(always)]
+    pub fn new_slice(bytes: B) -> Option<Ref<B, [T]>> {
+        Self::from_bytes(bytes).ok()
+    }
+}
+
+impl<B, T> Ref<B, [T]>
+where
+    B: ByteSlice,
+    T: Unaligned + Immutable,
+{
+    #[deprecated(
+        since = "0.8.0",
+        note = "`Ref::from_bytes` now supports slices; for `T: Unaligned`, the returned `CastError` implements `Into<SizeError>`"
+    )]
+    #[doc(hidden)]
+    #[inline(always)]
+    pub fn new_slice_unaligned(bytes: B) -> Option<Ref<B, [T]>> {
+        Ref::from_bytes(bytes).ok()
+    }
+}
+
+impl<'a, B, T> Ref<B, [T]>
+where
+    B: 'a + IntoByteSlice<'a>,
+    T: FromBytes + Immutable,
+{
+    #[deprecated(since = "0.8.0", note = "`Ref::into_ref` now supports slices")]
+    #[doc(hidden)]
+    #[inline(always)]
+    pub fn into_slice(self) -> &'a [T] {
+        Ref::into_ref(self)
+    }
+}
+
+impl<'a, B, T> Ref<B, [T]>
+where
+    B: 'a + IntoByteSliceMut<'a>,
+    T: FromBytes + IntoBytes + Immutable,
+{
+    #[deprecated(since = "0.8.0", note = "`Ref::into_mut` now supports slices")]
+    #[doc(hidden)]
+    #[inline(always)]
+    pub fn into_mut_slice(self) -> &'a mut [T] {
+        Ref::into_mut(self)
+    }
+}
+
+impl<B, T> Ref<B, [T]>
+where
+    B: SplitByteSlice,
+    T: Immutable,
+{
+    #[deprecated(since = "0.8.0", note = "replaced by `Ref::from_prefix_with_elems`")]
+    #[must_use = "has no side effects"]
+    #[doc(hidden)]
+    #[inline(always)]
+    pub fn new_slice_from_prefix(bytes: B, count: usize) -> Option<(Ref<B, [T]>, B)> {
+        Ref::from_prefix_with_elems(bytes, count).ok()
+    }
+
+    #[deprecated(since = "0.8.0", note = "replaced by `Ref::from_suffix_with_elems`")]
+    #[must_use = "has no side effects"]
+    #[doc(hidden)]
+    #[inline(always)]
+    pub fn new_slice_from_suffix(bytes: B, count: usize) -> Option<(B, Ref<B, [T]>)> {
+        Ref::from_suffix_with_elems(bytes, count).ok()
+    }
+}
+
+impl<B, T> Ref<B, [T]>
+where
+    B: SplitByteSlice,
+    T: Unaligned + Immutable,
+{
+    #[deprecated(
+        since = "0.8.0",
+        note = "use `Ref::from_prefix_with_elems`; for `T: Unaligned`, the returned `CastError` implements `Into<SizeError>`"
+    )]
+    #[doc(hidden)]
+    #[must_use = "has no side effects"]
+    #[inline(always)]
+    pub fn new_slice_unaligned_from_prefix(bytes: B, count: usize) -> Option<(Ref<B, [T]>, B)> {
+        Ref::from_prefix_with_elems(bytes, count).ok()
+    }
+
+    #[deprecated(
+        since = "0.8.0",
+        note = "use `Ref::from_suffix_with_elems`; for `T: Unaligned`, the returned `CastError` implements `Into<SizeError>`"
+    )]
+    #[doc(hidden)]
+    #[must_use = "has no side effects"]
+    #[inline(always)]
+    pub fn new_slice_unaligned_from_suffix(bytes: B, count: usize) -> Option<(B, Ref<B, [T]>)> {
+        Ref::from_suffix_with_elems(bytes, count).ok()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    #[allow(deprecated)]
+    fn test_deprecated_ref_methods() {
+        let bytes = &[0u8; 1][..];
+        let bytes_slice = &[0u8; 4][..];
+
+        let r: Option<Ref<&[u8], u8>> = Ref::new(bytes);
+        assert!(r.is_some());
+
+        let r: Option<(Ref<&[u8], u8>, &[u8])> = Ref::new_from_prefix(bytes);
+        assert!(r.is_some());
+
+        let r: Option<(&[u8], Ref<&[u8], u8>)> = Ref::new_from_suffix(bytes);
+        assert!(r.is_some());
+
+        let r: Option<Ref<&[u8], u8>> = Ref::new_unaligned(bytes);
+        assert!(r.is_some());
+
+        let r: Option<(Ref<&[u8], u8>, &[u8])> = Ref::new_unaligned_from_prefix(bytes);
+        assert!(r.is_some());
+
+        let r: Option<(&[u8], Ref<&[u8], u8>)> = Ref::new_unaligned_from_suffix(bytes);
+        assert!(r.is_some());
+
+        let r: Option<Ref<&[u8], [u8]>> = Ref::new_slice(bytes_slice);
+        assert!(r.is_some());
+
+        let r: Option<Ref<&[u8], [u8]>> = Ref::new_slice_unaligned(bytes_slice);
+        assert!(r.is_some());
+
+        let r: Option<(Ref<&[u8], [u8]>, &[u8])> = Ref::new_slice_from_prefix(bytes_slice, 1);
+        assert!(r.is_some());
+
+        let r: Option<(&[u8], Ref<&[u8], [u8]>)> = Ref::new_slice_from_suffix(bytes_slice, 1);
+        assert!(r.is_some());
+
+        let r: Option<(Ref<&[u8], [u8]>, &[u8])> =
+            Ref::new_slice_unaligned_from_prefix(bytes_slice, 1);
+        assert!(r.is_some());
+
+        let r: Option<(&[u8], Ref<&[u8], [u8]>)> =
+            Ref::new_slice_unaligned_from_suffix(bytes_slice, 1);
+        assert!(r.is_some());
+    }
+
+    #[test]
+    #[allow(deprecated)]
+    fn test_deprecated_into_slice() {
+        let bytes = &[0u8; 4][..];
+        let r: Ref<&[u8], [u8]> = Ref::from_bytes(bytes).unwrap();
+        let slice: &[u8] = r.into_slice();
+        assert_eq!(slice.len(), 4);
+    }
+
+    #[test]
+    #[allow(deprecated)]
+    fn test_deprecated_into_mut_slice() {
+        let mut bytes = [0u8; 4];
+        let r: Ref<&mut [u8], [u8]> = Ref::from_bytes(&mut bytes[..]).unwrap();
+        let slice: &mut [u8] = r.into_mut_slice();
+        assert_eq!(slice.len(), 4);
+    }
+}