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, 125 insertions, 0 deletions

diff --git a/drivers/edac/edac_module.h b/drivers/edac/edac_module.h
new file mode 100644
index 000000000..47593afdc
--- /dev/null
+++ b/drivers/edac/edac_module.h
@@ -0,0 +1,125 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/*
+ * edac_module.h
+ *
+ * For defining functions/data for within the EDAC_CORE module only
+ *
+ * written by doug thompson <norsk5@xmission.h>
+ */
+
+#ifndef	__EDAC_MODULE_H__
+#define	__EDAC_MODULE_H__
+
+#include <acpi/ghes.h>
+#include "edac_mc.h"
+#include "edac_pci.h"
+#include "edac_device.h"
+
+/*
+ * INTERNAL EDAC MODULE:
+ * EDAC memory controller sysfs create/remove functions
+ * and setup/teardown functions
+ *
+ * edac_mc objects
+ */
+	/* on edac_mc_sysfs.c */
+int edac_mc_sysfs_init(void);
+void edac_mc_sysfs_exit(void);
+extern int edac_create_sysfs_mci_device(struct mem_ctl_info *mci,
+					const struct attribute_group **groups);
+extern void edac_remove_sysfs_mci_device(struct mem_ctl_info *mci);
+extern int edac_mc_get_log_ue(void);
+extern int edac_mc_get_log_ce(void);
+extern int edac_mc_get_panic_on_ue(void);
+extern unsigned int edac_mc_get_poll_msec(void);
+
+unsigned edac_dimm_info_location(struct dimm_info *dimm, char *buf,
+				 unsigned len);
+
+	/* on edac_device.c */
+extern int edac_device_register_sysfs_main_kobj(
+				struct edac_device_ctl_info *edac_dev);
+extern void edac_device_unregister_sysfs_main_kobj(
+				struct edac_device_ctl_info *edac_dev);
+extern int edac_device_create_sysfs(struct edac_device_ctl_info *edac_dev);
+extern void edac_device_remove_sysfs(struct edac_device_ctl_info *edac_dev);
+
+/* edac core workqueue: single CPU mode */
+int edac_workqueue_setup(void);
+void edac_workqueue_teardown(void);
+bool edac_queue_work(struct delayed_work *work, unsigned long delay);
+bool edac_stop_work(struct delayed_work *work);
+bool edac_mod_work(struct delayed_work *work, unsigned long delay);
+
+extern void edac_device_reset_delay_period(struct edac_device_ctl_info
+					   *edac_dev, unsigned long msec);
+extern void edac_mc_reset_delay_period(unsigned long value);
+
+/*
+ * EDAC debugfs functions
+ */
+
+#define edac_debugfs_remove_recursive debugfs_remove_recursive
+#define edac_debugfs_remove debugfs_remove
+#ifdef CONFIG_EDAC_DEBUG
+void edac_debugfs_init(void);
+void edac_debugfs_exit(void);
+void edac_create_debugfs_nodes(struct mem_ctl_info *mci);
+struct dentry *edac_debugfs_create_dir(const char *dirname);
+struct dentry *
+edac_debugfs_create_dir_at(const char *dirname, struct dentry *parent);
+struct dentry *
+edac_debugfs_create_file(const char *name, umode_t mode, struct dentry *parent,
+			 void *data, const struct file_operations *fops);
+void edac_debugfs_create_x8(const char *name, umode_t mode,
+			    struct dentry *parent, u8 *value);
+void edac_debugfs_create_x16(const char *name, umode_t mode,
+			     struct dentry *parent, u16 *value);
+void edac_debugfs_create_x32(const char *name, umode_t mode,
+			     struct dentry *parent, u32 *value);
+#else
+static inline void edac_debugfs_init(void)					{ }
+static inline void edac_debugfs_exit(void)					{ }
+static inline void edac_create_debugfs_nodes(struct mem_ctl_info *mci)		{ }
+static inline struct dentry *edac_debugfs_create_dir(const char *dirname)	{ return NULL; }
+static inline struct dentry *
+edac_debugfs_create_dir_at(const char *dirname, struct dentry *parent)		{ return NULL; }
+static inline struct dentry *
+edac_debugfs_create_file(const char *name, umode_t mode, struct dentry *parent,
+			 void *data, const struct file_operations *fops)	{ return NULL; }
+static inline void edac_debugfs_create_x8(const char *name, umode_t mode,
+					  struct dentry *parent, u8 *value)	{ }
+static inline void edac_debugfs_create_x16(const char *name, umode_t mode,
+					   struct dentry *parent, u16 *value)	{ }
+static inline void edac_debugfs_create_x32(const char *name, umode_t mode,
+		       struct dentry *parent, u32 *value)			{ }
+#endif
+
+/*
+ * EDAC PCI functions
+ */
+#ifdef	CONFIG_PCI
+extern void edac_pci_do_parity_check(void);
+extern void edac_pci_clear_parity_errors(void);
+extern int edac_sysfs_pci_setup(void);
+extern void edac_sysfs_pci_teardown(void);
+extern int edac_pci_get_check_errors(void);
+extern int edac_pci_get_poll_msec(void);
+extern void edac_pci_remove_sysfs(struct edac_pci_ctl_info *pci);
+extern void edac_pci_handle_pe(struct edac_pci_ctl_info *pci, const char *msg);
+extern void edac_pci_handle_npe(struct edac_pci_ctl_info *pci,
+				const char *msg);
+#else				/* CONFIG_PCI */
+/* pre-process these away */
+#define edac_pci_do_parity_check()
+#define edac_pci_clear_parity_errors()
+#define edac_sysfs_pci_setup()  (0)
+#define edac_sysfs_pci_teardown()
+#define edac_pci_get_check_errors()
+#define edac_pci_get_poll_msec()
+#define edac_pci_handle_pe()
+#define edac_pci_handle_npe()
+#endif				/* CONFIG_PCI */
+
+#endif				/* __EDAC_MODULE_H__ */