From 27600805e62f800bacf990354632eae4e487d34c Mon Sep 17 00:00:00 2001
From: Yazen Ghannam <yazen.ghannam@amd.com>
Date: Thu, 3 Sep 2026 10:43:25 -0500
Subject: x86/amd_node: Fix PCI device reference counting in amd_smn_init()

The local "root" pointer is a temporary variable used during the device
search. Therefore, refcount related to the search iterators should be cleaned
up after the search is complete.

Use the __free() cleanup macro to ensure the refcount is decremented when the
temporary pointer goes out of scope.

Additionally, increment the refcount when caching a root pointer. This ensures
the in-use refcount is separate from the temporary search refcounting.

Finally, drop the redundant "root = NULL" before the second search loop. The
pci_get_class() iterator always decrements the refcount of its "from"
argument, so the first loop can only fall through with "root" already NULL.

Fixes: 0a4b61d9c2e4 ("x86/amd_node: Fix AMD root device caching")
Closes: https://sashiko.dev/#/patchset/20260806160159.230453-1-jason.andryuk%40amd.com
Reported-by: Sashiko <sashiko-bot@kernel.org>
Assisted-by: LLM
Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Cc: <stable@kernel.org>
Link: https://patch.msgid.link/20260903154325.74343-1-yazen.ghannam@amd.com
---
 rust/syn/ident.rs | 110 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 110 insertions(+)
 create mode 100644 rust/syn/ident.rs

(limited to 'rust/syn/ident.rs')

diff --git a/rust/syn/ident.rs b/rust/syn/ident.rs
new file mode 100644
index 000000000..03ccebf9c
--- /dev/null
+++ b/rust/syn/ident.rs
@@ -0,0 +1,110 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+#[cfg(feature = "parsing")]
+use crate::lookahead;
+
+pub use proc_macro2::Ident;
+
+#[cfg(feature = "parsing")]
+pub_if_not_doc! {
+    #[doc(hidden)]
+    #[allow(non_snake_case)]
+    pub fn Ident(marker: lookahead::TokenMarker) -> Ident {
+        match marker {}
+    }
+}
+
+macro_rules! ident_from_token {
+    ($token:ident) => {
+        impl From<Token![$token]> for Ident {
+            fn from(token: Token![$token]) -> Ident {
+                Ident::new(stringify!($token), token.span)
+            }
+        }
+    };
+}
+
+ident_from_token!(self);
+ident_from_token!(Self);
+ident_from_token!(super);
+ident_from_token!(crate);
+ident_from_token!(extern);
+
+impl From<Token![_]> for Ident {
+    fn from(token: Token![_]) -> Ident {
+        Ident::new("_", token.span)
+    }
+}
+
+pub(crate) fn xid_ok(symbol: &str) -> bool {
+    let mut chars = symbol.chars();
+    let first = chars.next().unwrap();
+    if !(first == '_' || first.is_ascii_alphabetic()) {
+        return false;
+    }
+    for ch in chars {
+        if !(ch == '_' || ch.is_ascii_alphanumeric()) {
+            return false;
+        }
+    }
+    true
+}
+
+#[cfg(feature = "parsing")]
+mod parsing {
+    use crate::buffer::Cursor;
+    use crate::error::Result;
+    use crate::parse::{Parse, ParseStream};
+    use crate::token::Token;
+    use proc_macro2::Ident;
+
+    fn accept_as_ident(ident: &Ident) -> bool {
+        match ident.to_string().as_str() {
+            "_" |
+            // Based on https://doc.rust-lang.org/1.65.0/reference/keywords.html
+            "abstract" | "as" | "async" | "await" | "become" | "box" | "break" |
+            "const" | "continue" | "crate" | "do" | "dyn" | "else" | "enum" |
+            "extern" | "false" | "final" | "fn" | "for" | "if" | "impl" | "in" |
+            "let" | "loop" | "macro" | "match" | "mod" | "move" | "mut" |
+            "override" | "priv" | "pub" | "ref" | "return" | "Self" | "self" |
+            "static" | "struct" | "super" | "trait" | "true" | "try" | "type" |
+            "typeof" | "unsafe" | "unsized" | "use" | "virtual" | "where" |
+            "while" | "yield" => false,
+            _ => true,
+        }
+    }
+
+    #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
+    impl Parse for Ident {
+        fn parse(input: ParseStream) -> Result<Self> {
+            input.step(|cursor| {
+                if let Some((ident, rest)) = cursor.ident() {
+                    if accept_as_ident(&ident) {
+                        Ok((ident, rest))
+                    } else {
+                        Err(cursor.error(format_args!(
+                            "expected identifier, found keyword `{}`",
+                            ident,
+                        )))
+                    }
+                } else {
+                    Err(cursor.error("expected identifier"))
+                }
+            })
+        }
+    }
+
+    impl Token for Ident {
+        fn peek(cursor: Cursor) -> bool {
+            if let Some((ident, _rest)) = cursor.ident() {
+                accept_as_ident(&ident)
+            } else {
+                false
+            }
+        }
+
+        fn display() -> &'static str {
+            "identifier"
+        }
+    }
+}
-- 
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