Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 429 insertions, 0 deletions

diff --git a/rust/syn/meta.rs b/rust/syn/meta.rs
new file mode 100644
index 000000000..2dd138e6d
--- /dev/null
+++ b/rust/syn/meta.rs
@@ -0,0 +1,429 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+//! Facility for interpreting structured content inside of an `Attribute`.
+
+use crate::error::{Error, Result};
+use crate::ext::IdentExt as _;
+use crate::lit::Lit;
+use crate::parse::{ParseStream, Parser};
+use crate::path::{Path, PathSegment};
+use crate::punctuated::Punctuated;
+use proc_macro2::Ident;
+use std::fmt::Display;
+
+/// Make a parser that is usable with `parse_macro_input!` in a
+/// `#[proc_macro_attribute]` macro.
+///
+/// *Warning:* When parsing attribute args **other than** the
+/// `proc_macro::TokenStream` input of a `proc_macro_attribute`, you do **not**
+/// need this function. In several cases your callers will get worse error
+/// messages if you use this function, because the surrounding delimiter's span
+/// is concealed from attribute macros by rustc. Use
+/// [`Attribute::parse_nested_meta`] instead.
+///
+/// [`Attribute::parse_nested_meta`]: crate::Attribute::parse_nested_meta
+///
+/// # Example
+///
+/// This example implements an attribute macro whose invocations look like this:
+///
+/// ```
+/// # const IGNORE: &str = stringify! {
+/// #[tea(kind = "EarlGrey", hot)]
+/// struct Picard {...}
+/// # };
+/// ```
+///
+/// The "parameters" supported by the attribute are:
+///
+/// - `kind = "..."`
+/// - `hot`
+/// - `with(sugar, milk, ...)`, a comma-separated list of ingredients
+///
+/// ```
+/// # extern crate proc_macro;
+/// #
+/// use proc_macro::TokenStream;
+/// use syn::{parse_macro_input, LitStr, Path};
+///
+/// # const IGNORE: &str = stringify! {
+/// #[proc_macro_attribute]
+/// # };
+/// pub fn tea(args: TokenStream, input: TokenStream) -> TokenStream {
+///     let mut kind: Option<LitStr> = None;
+///     let mut hot: bool = false;
+///     let mut with: Vec<Path> = Vec::new();
+///     let tea_parser = syn::meta::parser(|meta| {
+///         if meta.path.is_ident("kind") {
+///             kind = Some(meta.value()?.parse()?);
+///             Ok(())
+///         } else if meta.path.is_ident("hot") {
+///             hot = true;
+///             Ok(())
+///         } else if meta.path.is_ident("with") {
+///             meta.parse_nested_meta(|meta| {
+///                 with.push(meta.path);
+///                 Ok(())
+///             })
+///         } else {
+///             Err(meta.error("unsupported tea property"))
+///         }
+///     });
+///
+///     parse_macro_input!(args with tea_parser);
+///     eprintln!("kind={kind:?} hot={hot} with={with:?}");
+///
+///     /* ... */
+/// #   TokenStream::new()
+/// }
+/// ```
+///
+/// The `syn::meta` library will take care of dealing with the commas including
+/// trailing commas, and producing sensible error messages on unexpected input.
+///
+/// ```console
+/// error: expected `,`
+///  --> src/main.rs:3:37
+///   |
+/// 3 | #[tea(kind = "EarlGrey", with(sugar = "lol", milk))]
+///   |                                     ^
+/// ```
+///
+/// # Example
+///
+/// Same as above but we factor out most of the logic into a separate function.
+///
+/// ```
+/// # extern crate proc_macro;
+/// #
+/// use proc_macro::TokenStream;
+/// use syn::meta::ParseNestedMeta;
+/// use syn::parse::{Parser, Result};
+/// use syn::{parse_macro_input, LitStr, Path};
+///
+/// # const IGNORE: &str = stringify! {
+/// #[proc_macro_attribute]
+/// # };
+/// pub fn tea(args: TokenStream, input: TokenStream) -> TokenStream {
+///     let mut attrs = TeaAttributes::default();
+///     let tea_parser = syn::meta::parser(|meta| attrs.parse(meta));
+///     parse_macro_input!(args with tea_parser);
+///
+///     /* ... */
+/// #   TokenStream::new()
+/// }
+///
+/// #[derive(Default)]
+/// struct TeaAttributes {
+///     kind: Option<LitStr>,
+///     hot: bool,
+///     with: Vec<Path>,
+/// }
+///
+/// impl TeaAttributes {
+///     fn parse(&mut self, meta: ParseNestedMeta) -> Result<()> {
+///         if meta.path.is_ident("kind") {
+///             self.kind = Some(meta.value()?.parse()?);
+///             Ok(())
+///         } else /* just like in last example */
+/// #           { unimplemented!() }
+///
+///     }
+/// }
+/// ```
+pub fn parser(logic: impl FnMut(ParseNestedMeta) -> Result<()>) -> impl Parser<Output = ()> {
+    |input: ParseStream| {
+        if input.is_empty() {
+            Ok(())
+        } else {
+            parse_nested_meta(input, logic)
+        }
+    }
+}
+
+/// Context for parsing a single property in the conventional syntax for
+/// structured attributes.
+///
+/// # Examples
+///
+/// Refer to usage examples on the following two entry-points:
+///
+/// - [`Attribute::parse_nested_meta`] if you have an entire `Attribute` to
+///   parse. Always use this if possible. Generally this is able to produce
+///   better error messages because `Attribute` holds span information for all
+///   of the delimiters therein.
+///
+/// - [`syn::meta::parser`] if you are implementing a `proc_macro_attribute`
+///   macro and parsing the arguments to the attribute macro, i.e. the ones
+///   written in the same attribute that dispatched the macro invocation. Rustc
+///   does not pass span information for the surrounding delimiters into the
+///   attribute macro invocation in this situation, so error messages might be
+///   less precise.
+///
+/// [`Attribute::parse_nested_meta`]: crate::Attribute::parse_nested_meta
+/// [`syn::meta::parser`]: crate::meta::parser
+#[non_exhaustive]
+pub struct ParseNestedMeta<'a> {
+    pub path: Path,
+    pub input: ParseStream<'a>,
+}
+
+impl<'a> ParseNestedMeta<'a> {
+    /// Used when parsing `key = "value"` syntax.
+    ///
+    /// All it does is advance `meta.input` past the `=` sign in the input. You
+    /// could accomplish the same effect by writing
+    /// `meta.parse::<Token![=]>()?`, so at most it is a minor convenience to
+    /// use `meta.value()?`.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use syn::{parse_quote, Attribute, LitStr};
+    ///
+    /// let attr: Attribute = parse_quote! {
+    ///     #[tea(kind = "EarlGrey")]
+    /// };
+    ///                                          // conceptually:
+    /// if attr.path().is_ident("tea") {         // this parses the `tea`
+    ///     attr.parse_nested_meta(|meta| {      // this parses the `(`
+    ///         if meta.path.is_ident("kind") {  // this parses the `kind`
+    ///             let value = meta.value()?;   // this parses the `=`
+    ///             let s: LitStr = value.parse()?;  // this parses `"EarlGrey"`
+    ///             if s.value() == "EarlGrey" {
+    ///                 // ...
+    ///             }
+    ///             Ok(())
+    ///         } else {
+    ///             Err(meta.error("unsupported attribute"))
+    ///         }
+    ///     })?;
+    /// }
+    /// # anyhow::Ok(())
+    /// ```
+    pub fn value(&self) -> Result<ParseStream<'a>> {
+        self.input.parse::<Token![=]>()?;
+        Ok(self.input)
+    }
+
+    /// Used when parsing `list(...)` syntax **if** the content inside the
+    /// nested parentheses is also expected to conform to Rust's structured
+    /// attribute convention.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use syn::{parse_quote, Attribute};
+    ///
+    /// let attr: Attribute = parse_quote! {
+    ///     #[tea(with(sugar, milk))]
+    /// };
+    ///
+    /// if attr.path().is_ident("tea") {
+    ///     attr.parse_nested_meta(|meta| {
+    ///         if meta.path.is_ident("with") {
+    ///             meta.parse_nested_meta(|meta| {  // <---
+    ///                 if meta.path.is_ident("sugar") {
+    ///                     // Here we can go even deeper if needed.
+    ///                     Ok(())
+    ///                 } else if meta.path.is_ident("milk") {
+    ///                     Ok(())
+    ///                 } else {
+    ///                     Err(meta.error("unsupported ingredient"))
+    ///                 }
+    ///             })
+    ///         } else {
+    ///             Err(meta.error("unsupported tea property"))
+    ///         }
+    ///     })?;
+    /// }
+    /// # anyhow::Ok(())
+    /// ```
+    ///
+    /// # Counterexample
+    ///
+    /// If you don't need `parse_nested_meta`'s help in parsing the content
+    /// written within the nested parentheses, keep in mind that you can always
+    /// just parse it yourself from the exposed ParseStream. Rust syntax permits
+    /// arbitrary tokens within those parentheses so for the crazier stuff,
+    /// `parse_nested_meta` is not what you want.
+    ///
+    /// ```
+    /// use syn::{parenthesized, parse_quote, Attribute, LitInt};
+    ///
+    /// let attr: Attribute = parse_quote! {
+    ///     #[repr(align(32))]
+    /// };
+    ///
+    /// let mut align: Option<LitInt> = None;
+    /// if attr.path().is_ident("repr") {
+    ///     attr.parse_nested_meta(|meta| {
+    ///         if meta.path.is_ident("align") {
+    ///             let content;
+    ///             parenthesized!(content in meta.input);
+    ///             align = Some(content.parse()?);
+    ///             Ok(())
+    ///         } else {
+    ///             Err(meta.error("unsupported repr"))
+    ///         }
+    ///     })?;
+    /// }
+    /// # anyhow::Ok(())
+    /// ```
+    pub fn parse_nested_meta(
+        &self,
+        logic: impl FnMut(ParseNestedMeta) -> Result<()>,
+    ) -> Result<()> {
+        let content;
+        parenthesized!(content in self.input);
+        parse_nested_meta(&content, logic)
+    }
+
+    /// Report that the attribute's content did not conform to expectations.
+    ///
+    /// The span of the resulting error will cover `meta.path` *and* everything
+    /// that has been parsed so far since it.
+    ///
+    /// There are 2 ways you might call this. First, if `meta.path` is not
+    /// something you recognize:
+    ///
+    /// ```
+    /// # use syn::Attribute;
+    /// #
+    /// # fn example(attr: &Attribute) -> syn::Result<()> {
+    /// attr.parse_nested_meta(|meta| {
+    ///     if meta.path.is_ident("kind") {
+    ///         // ...
+    ///         Ok(())
+    ///     } else {
+    ///         Err(meta.error("unsupported tea property"))
+    ///     }
+    /// })?;
+    /// # Ok(())
+    /// # }
+    /// ```
+    ///
+    /// In this case, it behaves exactly like
+    /// `syn::Error::new_spanned(&meta.path, "message...")`.
+    ///
+    /// ```console
+    /// error: unsupported tea property
+    ///  --> src/main.rs:3:26
+    ///   |
+    /// 3 | #[tea(kind = "EarlGrey", wat = "foo")]
+    ///   |                          ^^^
+    /// ```
+    ///
+    /// More usefully, the second place is if you've already parsed a value but
+    /// have decided not to accept the value:
+    ///
+    /// ```
+    /// # use syn::Attribute;
+    /// #
+    /// # fn example(attr: &Attribute) -> syn::Result<()> {
+    /// use syn::Expr;
+    ///
+    /// attr.parse_nested_meta(|meta| {
+    ///     if meta.path.is_ident("kind") {
+    ///         let expr: Expr = meta.value()?.parse()?;
+    ///         match expr {
+    ///             Expr::Lit(expr) => /* ... */
+    /// #               unimplemented!(),
+    ///             Expr::Path(expr) => /* ... */
+    /// #               unimplemented!(),
+    ///             Expr::Macro(expr) => /* ... */
+    /// #               unimplemented!(),
+    ///             _ => Err(meta.error("tea kind must be a string literal, path, or macro")),
+    ///         }
+    ///     } else /* as above */
+    /// #       { unimplemented!() }
+    ///
+    /// })?;
+    /// # Ok(())
+    /// # }
+    /// ```
+    ///
+    /// ```console
+    /// error: tea kind must be a string literal, path, or macro
+    ///  --> src/main.rs:3:7
+    ///   |
+    /// 3 | #[tea(kind = async { replicator.await })]
+    ///   |       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+    /// ```
+    ///
+    /// Often you may want to use `syn::Error::new_spanned` even in this
+    /// situation. In the above code, that would be:
+    ///
+    /// ```
+    /// # use syn::{Error, Expr};
+    /// #
+    /// # fn example(expr: Expr) -> syn::Result<()> {
+    ///     match expr {
+    ///         Expr::Lit(expr) => /* ... */
+    /// #           unimplemented!(),
+    ///         Expr::Path(expr) => /* ... */
+    /// #           unimplemented!(),
+    ///         Expr::Macro(expr) => /* ... */
+    /// #           unimplemented!(),
+    ///         _ => Err(Error::new_spanned(expr, "unsupported expression type for `kind`")),
+    ///     }
+    /// # }
+    /// ```
+    ///
+    /// ```console
+    /// error: unsupported expression type for `kind`
+    ///  --> src/main.rs:3:14
+    ///   |
+    /// 3 | #[tea(kind = async { replicator.await })]
+    ///   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^
+    /// ```
+    pub fn error(&self, msg: impl Display) -> Error {
+        let start_span = self.path.segments[0].ident.span();
+        let end_span = self.input.cursor().prev_span();
+        crate::error::new2(start_span, end_span, msg)
+    }
+}
+
+pub(crate) fn parse_nested_meta(
+    input: ParseStream,
+    mut logic: impl FnMut(ParseNestedMeta) -> Result<()>,
+) -> Result<()> {
+    loop {
+        let path = input.call(parse_meta_path)?;
+        logic(ParseNestedMeta { path, input })?;
+        if input.is_empty() {
+            return Ok(());
+        }
+        input.parse::<Token![,]>()?;
+        if input.is_empty() {
+            return Ok(());
+        }
+    }
+}
+
+// Like Path::parse_mod_style, but accepts keywords in the path.
+fn parse_meta_path(input: ParseStream) -> Result<Path> {
+    Ok(Path {
+        leading_colon: input.parse()?,
+        segments: {
+            let mut segments = Punctuated::new();
+            if input.peek(Ident::peek_any) {
+                let ident = Ident::parse_any(input)?;
+                segments.push_value(PathSegment::from(ident));
+            } else if input.is_empty() {
+                return Err(input.error("expected nested attribute"));
+            } else if input.peek(Lit) {
+                return Err(input.error("unexpected literal in nested attribute, expected ident"));
+            } else {
+                return Err(input.error("unexpected token in nested attribute, expected ident"));
+            }
+            while input.peek(Token![::]) {
+                let punct = input.parse()?;
+                segments.push_punct(punct);
+                let ident = Ident::parse_any(input)?;
+                segments.push_value(PathSegment::from(ident));
+            }
+            segments
+        },
+    })
+}