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, 77 insertions, 0 deletions

diff --git a/drivers/scsi/sr.h b/drivers/scsi/sr.h
new file mode 100644
index 000000000..2d92f9cb6
--- /dev/null
+++ b/drivers/scsi/sr.h
@@ -0,0 +1,77 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ *      sr.h by David Giller
+ *      CD-ROM disk driver header file
+ *      
+ *      adapted from:
+ *      sd.h Copyright (C) 1992 Drew Eckhardt 
+ *      SCSI disk driver header file by
+ *              Drew Eckhardt 
+ *
+ *      <drew@colorado.edu>
+ *
+ *       Modified by Eric Youngdale eric@andante.org to
+ *       add scatter-gather, multiple outstanding request, and other
+ *       enhancements.
+ */
+
+#ifndef _SR_H
+#define _SR_H
+
+#include <linux/mutex.h>
+
+#define MAX_RETRIES	3
+#define SR_TIMEOUT	(30 * HZ)
+
+struct scsi_device;
+
+/* The CDROM is fairly slow, so we need a little extra time */
+/* In fact, it is very slow if it has to spin up first */
+#define IOCTL_TIMEOUT 30*HZ
+
+
+typedef struct scsi_cd {
+	unsigned capacity;	/* size in blocks                       */
+	struct scsi_device *device;
+	unsigned int vendor;	/* vendor code, see sr_vendor.c         */
+	unsigned long ms_offset;	/* for reading multisession-CD's        */
+	unsigned use:1;		/* is this device still supportable     */
+	unsigned xa_flag:1;	/* CD has XA sectors ? */
+	unsigned readcd_known:1;	/* drive supports READ_CD (0xbe) */
+	unsigned readcd_cdda:1;	/* reading audio data using READ_CD */
+	unsigned media_present:1;	/* media is present */
+
+	/* GET_EVENT spurious event handling, blk layer guarantees exclusion */
+	int tur_mismatch;		/* nr of get_event TUR mismatches */
+	bool tur_changed:1;		/* changed according to TUR */
+	bool get_event_changed:1;	/* changed according to GET_EVENT */
+	bool ignore_get_event:1;	/* GET_EVENT is unreliable, use TUR */
+
+	struct cdrom_device_info cdi;
+	struct mutex lock;
+	struct gendisk *disk;
+} Scsi_CD;
+
+#define sr_printk(prefix, cd, fmt, a...) \
+	sdev_prefix_printk(prefix, (cd)->device, (cd)->cdi.name, fmt, ##a)
+
+int sr_do_ioctl(Scsi_CD *, struct packet_command *);
+
+int sr_lock_door(struct cdrom_device_info *, int);
+int sr_tray_move(struct cdrom_device_info *, int);
+int sr_drive_status(struct cdrom_device_info *, int);
+int sr_disk_status(struct cdrom_device_info *);
+int sr_get_last_session(struct cdrom_device_info *, struct cdrom_multisession *);
+int sr_get_mcn(struct cdrom_device_info *, struct cdrom_mcn *);
+int sr_reset(struct cdrom_device_info *);
+int sr_select_speed(struct cdrom_device_info *cdi, unsigned long speed);
+int sr_audio_ioctl(struct cdrom_device_info *, unsigned int, void *);
+
+int sr_is_xa(Scsi_CD *);
+
+/* sr_vendor.c */
+void sr_vendor_init(Scsi_CD *);
+int sr_cd_check(struct cdrom_device_info *);
+int sr_set_blocklength(Scsi_CD *, int blocklength);
+
+#endif