x86/amd_node: Fix PCI device reference counting in amd_smn_init()grafted

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

1 files changed, 82 insertions, 0 deletions

diff --git a/fs/tracefs/internal.h b/fs/tracefs/internal.h
new file mode 100644
index 000000000..c61481d04
--- /dev/null
+++ b/fs/tracefs/internal.h
@@ -0,0 +1,82 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _TRACEFS_INTERNAL_H
+#define _TRACEFS_INTERNAL_H
+
+enum {
+	TRACEFS_EVENT_INODE		= BIT(1),
+	TRACEFS_GID_PERM_SET		= BIT(2),
+	TRACEFS_UID_PERM_SET		= BIT(3),
+	TRACEFS_INSTANCE_INODE		= BIT(4),
+};
+
+struct tracefs_inode {
+	struct inode            vfs_inode;
+	/* The below gets initialized with memset_after(ti, 0, vfs_inode) */
+	struct list_head	list;
+	unsigned long           flags;
+	void                    *private;
+};
+
+/*
+ * struct eventfs_attr - cache the mode and ownership of a eventfs entry
+ * @mode:	saved mode plus flags of what is saved
+ * @uid:	saved uid if changed
+ * @gid:	saved gid if changed
+ */
+struct eventfs_attr {
+	int				mode;
+	kuid_t				uid;
+	kgid_t				gid;
+};
+
+/*
+ * struct eventfs_inode - hold the properties of the eventfs directories.
+ * @list:	link list into the parent directory
+ * @rcu:	Union with @list for freeing
+ * @children:	link list into the child eventfs_inode
+ * @entries:	the array of entries representing the files in the directory
+ * @name:	the name of the directory to create
+ * @entry_attrs: Saved mode and ownership of the @d_children
+ * @data:	The private data to pass to the callbacks
+ * @attr:	Saved mode and ownership of eventfs_inode itself
+ * @is_freed:	Flag set if the eventfs is on its way to be freed
+ *                Note if is_freed is set, then dentry is corrupted.
+ * @is_events:	Flag set for only the top level "events" directory
+ * @nr_entries: The number of items in @entries
+ * @ino:	The saved inode number
+ */
+struct eventfs_inode {
+	struct list_head	list;
+	union {
+		struct list_head	children;
+		struct rcu_head		rcu;
+	};
+	const struct eventfs_entry	*entries;
+	const char			*name;
+	struct eventfs_attr		*entry_attrs;
+	void				*data;
+	struct eventfs_attr		attr;
+	struct kref			kref;
+	unsigned int			is_freed:1;
+	unsigned int			is_events:1;
+	unsigned int			nr_entries:30;
+	unsigned int			ino;
+};
+
+static inline struct tracefs_inode *get_tracefs(const struct inode *inode)
+{
+	return container_of(inode, struct tracefs_inode, vfs_inode);
+}
+
+struct dentry *tracefs_start_creating(const char *name, struct dentry *parent);
+struct dentry *tracefs_end_creating(struct dentry *dentry);
+struct dentry *tracefs_failed_creating(struct dentry *dentry);
+struct inode *tracefs_get_inode(struct super_block *sb);
+
+void eventfs_remount(struct tracefs_inode *ti, bool update_uid, bool update_gid);
+void eventfs_d_release(struct dentry *dentry);
+
+int eventfs_remount_lock(void);
+void eventfs_remount_unlock(int srcu_idx);
+
+#endif /* _TRACEFS_INTERNAL_H */