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, 86 insertions, 0 deletions

diff --git a/drivers/comedi/comedi_internal.h b/drivers/comedi/comedi_internal.h
new file mode 100644
index 000000000..41a3b09f8
--- /dev/null
+++ b/drivers/comedi/comedi_internal.h
@@ -0,0 +1,86 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _COMEDI_INTERNAL_H
+#define _COMEDI_INTERNAL_H
+
+#include <linux/compiler.h>
+#include <linux/types.h>
+
+/*
+ * various internal comedi stuff
+ */
+
+struct comedi_buf_map;
+struct comedi_devconfig;
+struct comedi_device;
+struct comedi_insn;
+struct comedi_rangeinfo;
+struct comedi_subdevice;
+struct device;
+
+int do_rangeinfo_ioctl(struct comedi_device *dev,
+		       struct comedi_rangeinfo *it);
+struct comedi_device *comedi_alloc_board_minor(struct device *hardware_device);
+void comedi_release_hardware_device(struct device *hardware_device);
+int comedi_alloc_subdevice_minor(struct comedi_subdevice *s);
+void comedi_free_subdevice_minor(struct comedi_subdevice *s);
+
+int comedi_buf_alloc(struct comedi_device *dev, struct comedi_subdevice *s,
+		     unsigned long new_size);
+void comedi_buf_reset(struct comedi_subdevice *s);
+bool comedi_buf_is_mmapped(struct comedi_subdevice *s);
+void comedi_buf_map_get(struct comedi_buf_map *bm);
+int comedi_buf_map_put(struct comedi_buf_map *bm);
+int comedi_buf_map_access(struct comedi_buf_map *bm, unsigned long offset,
+			  void *buf, int len, int write);
+struct comedi_buf_map *
+comedi_buf_map_from_subdev_get(struct comedi_subdevice *s);
+unsigned int comedi_buf_write_n_available(struct comedi_subdevice *s);
+unsigned int comedi_buf_write_n_allocated(struct comedi_subdevice *s);
+unsigned int _comedi_buf_write_alloc(struct comedi_subdevice *s,
+				     unsigned int nbytes);
+unsigned int _comedi_buf_write_free(struct comedi_subdevice *s,
+				    unsigned int nbytes);
+unsigned int _comedi_buf_read_n_available(struct comedi_subdevice *s);
+unsigned int _comedi_buf_read_alloc(struct comedi_subdevice *s,
+				    unsigned int nbytes);
+unsigned int _comedi_buf_read_free(struct comedi_subdevice *s,
+				   unsigned int nbytes);
+void _comedi_inc_scan_progress(struct comedi_subdevice *s,
+			       unsigned int num_bytes);
+void _comedi_event(struct comedi_device *dev, struct comedi_subdevice *s);
+void comedi_device_cancel_all(struct comedi_device *dev);
+bool comedi_can_auto_free_spriv(struct comedi_subdevice *s);
+
+extern unsigned int comedi_default_buf_size_kb;
+extern unsigned int comedi_default_buf_maxsize_kb;
+
+/* drivers.c */
+
+extern struct comedi_driver *comedi_drivers;
+extern struct mutex comedi_drivers_list_lock;
+
+int insn_inval(struct comedi_device *dev, struct comedi_subdevice *s,
+	       struct comedi_insn *insn, unsigned int *data);
+
+void comedi_device_detach_locked(struct comedi_device *dev);
+void comedi_device_detach(struct comedi_device *dev);
+int comedi_device_attach(struct comedi_device *dev,
+			 struct comedi_devconfig *it);
+
+#ifdef CONFIG_PROC_FS
+
+/* proc.c */
+
+void comedi_proc_init(void);
+void comedi_proc_cleanup(void);
+#else
+static inline void comedi_proc_init(void)
+{
+}
+
+static inline void comedi_proc_cleanup(void)
+{
+}
+#endif
+
+#endif /* _COMEDI_INTERNAL_H */