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, 221 insertions, 0 deletions

diff --git a/rust/syn/op.rs b/rust/syn/op.rs
new file mode 100644
index 000000000..73dada3fa
--- /dev/null
+++ b/rust/syn/op.rs
@@ -0,0 +1,221 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+ast_enum! {
+    /// A binary operator: `+`, `+=`, `&`.
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))]
+    #[non_exhaustive]
+    pub enum BinOp {
+        /// The `+` operator (addition)
+        Add(Token![+]),
+        /// The `-` operator (subtraction)
+        Sub(Token![-]),
+        /// The `*` operator (multiplication)
+        Mul(Token![*]),
+        /// The `/` operator (division)
+        Div(Token![/]),
+        /// The `%` operator (modulus)
+        Rem(Token![%]),
+        /// The `&&` operator (logical and)
+        And(Token![&&]),
+        /// The `||` operator (logical or)
+        Or(Token![||]),
+        /// The `^` operator (bitwise xor)
+        BitXor(Token![^]),
+        /// The `&` operator (bitwise and)
+        BitAnd(Token![&]),
+        /// The `|` operator (bitwise or)
+        BitOr(Token![|]),
+        /// The `<<` operator (shift left)
+        Shl(Token![<<]),
+        /// The `>>` operator (shift right)
+        Shr(Token![>>]),
+        /// The `==` operator (equality)
+        Eq(Token![==]),
+        /// The `<` operator (less than)
+        Lt(Token![<]),
+        /// The `<=` operator (less than or equal to)
+        Le(Token![<=]),
+        /// The `!=` operator (not equal to)
+        Ne(Token![!=]),
+        /// The `>=` operator (greater than or equal to)
+        Ge(Token![>=]),
+        /// The `>` operator (greater than)
+        Gt(Token![>]),
+        /// The `+=` operator
+        AddAssign(Token![+=]),
+        /// The `-=` operator
+        SubAssign(Token![-=]),
+        /// The `*=` operator
+        MulAssign(Token![*=]),
+        /// The `/=` operator
+        DivAssign(Token![/=]),
+        /// The `%=` operator
+        RemAssign(Token![%=]),
+        /// The `^=` operator
+        BitXorAssign(Token![^=]),
+        /// The `&=` operator
+        BitAndAssign(Token![&=]),
+        /// The `|=` operator
+        BitOrAssign(Token![|=]),
+        /// The `<<=` operator
+        ShlAssign(Token![<<=]),
+        /// The `>>=` operator
+        ShrAssign(Token![>>=]),
+    }
+}
+
+ast_enum! {
+    /// A unary operator: `*`, `!`, `-`.
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))]
+    #[non_exhaustive]
+    pub enum UnOp {
+        /// The `*` operator for dereferencing
+        Deref(Token![*]),
+        /// The `!` operator for logical inversion
+        Not(Token![!]),
+        /// The `-` operator for negation
+        Neg(Token![-]),
+    }
+}
+
+#[cfg(feature = "parsing")]
+pub(crate) mod parsing {
+    use crate::error::Result;
+    use crate::op::{BinOp, UnOp};
+    use crate::parse::{Parse, ParseStream};
+
+    #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
+    impl Parse for BinOp {
+        fn parse(input: ParseStream) -> Result<Self> {
+            if input.peek(Token![+=]) {
+                input.parse().map(BinOp::AddAssign)
+            } else if input.peek(Token![-=]) {
+                input.parse().map(BinOp::SubAssign)
+            } else if input.peek(Token![*=]) {
+                input.parse().map(BinOp::MulAssign)
+            } else if input.peek(Token![/=]) {
+                input.parse().map(BinOp::DivAssign)
+            } else if input.peek(Token![%=]) {
+                input.parse().map(BinOp::RemAssign)
+            } else if input.peek(Token![^=]) {
+                input.parse().map(BinOp::BitXorAssign)
+            } else if input.peek(Token![&=]) {
+                input.parse().map(BinOp::BitAndAssign)
+            } else if input.peek(Token![|=]) {
+                input.parse().map(BinOp::BitOrAssign)
+            } else if input.peek(Token![<<=]) {
+                input.parse().map(BinOp::ShlAssign)
+            } else if input.peek(Token![>>=]) {
+                input.parse().map(BinOp::ShrAssign)
+            } else if input.peek(Token![&&]) {
+                input.parse().map(BinOp::And)
+            } else if input.peek(Token![||]) {
+                input.parse().map(BinOp::Or)
+            } else if input.peek(Token![<<]) {
+                input.parse().map(BinOp::Shl)
+            } else if input.peek(Token![>>]) {
+                input.parse().map(BinOp::Shr)
+            } else if input.peek(Token![==]) {
+                input.parse().map(BinOp::Eq)
+            } else if input.peek(Token![<=]) {
+                input.parse().map(BinOp::Le)
+            } else if input.peek(Token![!=]) {
+                input.parse().map(BinOp::Ne)
+            } else if input.peek(Token![>=]) {
+                input.parse().map(BinOp::Ge)
+            } else if input.peek(Token![+]) {
+                input.parse().map(BinOp::Add)
+            } else if input.peek(Token![-]) {
+                input.parse().map(BinOp::Sub)
+            } else if input.peek(Token![*]) {
+                input.parse().map(BinOp::Mul)
+            } else if input.peek(Token![/]) {
+                input.parse().map(BinOp::Div)
+            } else if input.peek(Token![%]) {
+                input.parse().map(BinOp::Rem)
+            } else if input.peek(Token![^]) {
+                input.parse().map(BinOp::BitXor)
+            } else if input.peek(Token![&]) {
+                input.parse().map(BinOp::BitAnd)
+            } else if input.peek(Token![|]) {
+                input.parse().map(BinOp::BitOr)
+            } else if input.peek(Token![<]) {
+                input.parse().map(BinOp::Lt)
+            } else if input.peek(Token![>]) {
+                input.parse().map(BinOp::Gt)
+            } else {
+                Err(input.error("expected binary operator"))
+            }
+        }
+    }
+
+    #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
+    impl Parse for UnOp {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let lookahead = input.lookahead1();
+            if lookahead.peek(Token![*]) {
+                input.parse().map(UnOp::Deref)
+            } else if lookahead.peek(Token![!]) {
+                input.parse().map(UnOp::Not)
+            } else if lookahead.peek(Token![-]) {
+                input.parse().map(UnOp::Neg)
+            } else {
+                Err(lookahead.error())
+            }
+        }
+    }
+}
+
+#[cfg(feature = "printing")]
+mod printing {
+    use crate::op::{BinOp, UnOp};
+    use proc_macro2::TokenStream;
+    use quote::ToTokens;
+
+    #[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
+    impl ToTokens for BinOp {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            match self {
+                BinOp::Add(t) => t.to_tokens(tokens),
+                BinOp::Sub(t) => t.to_tokens(tokens),
+                BinOp::Mul(t) => t.to_tokens(tokens),
+                BinOp::Div(t) => t.to_tokens(tokens),
+                BinOp::Rem(t) => t.to_tokens(tokens),
+                BinOp::And(t) => t.to_tokens(tokens),
+                BinOp::Or(t) => t.to_tokens(tokens),
+                BinOp::BitXor(t) => t.to_tokens(tokens),
+                BinOp::BitAnd(t) => t.to_tokens(tokens),
+                BinOp::BitOr(t) => t.to_tokens(tokens),
+                BinOp::Shl(t) => t.to_tokens(tokens),
+                BinOp::Shr(t) => t.to_tokens(tokens),
+                BinOp::Eq(t) => t.to_tokens(tokens),
+                BinOp::Lt(t) => t.to_tokens(tokens),
+                BinOp::Le(t) => t.to_tokens(tokens),
+                BinOp::Ne(t) => t.to_tokens(tokens),
+                BinOp::Ge(t) => t.to_tokens(tokens),
+                BinOp::Gt(t) => t.to_tokens(tokens),
+                BinOp::AddAssign(t) => t.to_tokens(tokens),
+                BinOp::SubAssign(t) => t.to_tokens(tokens),
+                BinOp::MulAssign(t) => t.to_tokens(tokens),
+                BinOp::DivAssign(t) => t.to_tokens(tokens),
+                BinOp::RemAssign(t) => t.to_tokens(tokens),
+                BinOp::BitXorAssign(t) => t.to_tokens(tokens),
+                BinOp::BitAndAssign(t) => t.to_tokens(tokens),
+                BinOp::BitOrAssign(t) => t.to_tokens(tokens),
+                BinOp::ShlAssign(t) => t.to_tokens(tokens),
+                BinOp::ShrAssign(t) => t.to_tokens(tokens),
+            }
+        }
+    }
+
+    #[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
+    impl ToTokens for UnOp {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            match self {
+                UnOp::Deref(t) => t.to_tokens(tokens),
+                UnOp::Not(t) => t.to_tokens(tokens),
+                UnOp::Neg(t) => t.to_tokens(tokens),
+            }
+        }
+    }
+}