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, 105 insertions, 0 deletions

diff --git a/drivers/scsi/st_options.h b/drivers/scsi/st_options.h
new file mode 100644
index 000000000..2b6cabd7b
--- /dev/null
+++ b/drivers/scsi/st_options.h
@@ -0,0 +1,105 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+   The compile-time configurable defaults for the Linux SCSI tape driver.
+
+   Copyright 1995-2003 Kai Makisara.
+
+   Last modified: Thu Feb 21 21:47:07 2008 by kai.makisara
+*/
+
+#ifndef _ST_OPTIONS_H
+#define _ST_OPTIONS_H
+
+/* If TRY_DIRECT_IO is non-zero, the driver tries to transfer data directly
+   between the user buffer and tape drive. If this is not possible, driver
+   buffer is used. If TRY_DIRECT_IO is zero, driver buffer is always used. */
+#define TRY_DIRECT_IO 1
+
+/* The driver does not wait for some operations to finish before returning
+   to the user program if ST_NOWAIT is non-zero. This helps if the SCSI
+   adapter does not support multiple outstanding commands. However, the user
+   should not give a new tape command before the previous one has finished. */
+#define ST_NOWAIT 0
+
+/* If ST_IN_FILE_POS is nonzero, the driver positions the tape after the
+   record been read by the user program even if the tape has moved further
+   because of buffered reads. Should be set to zero to support also drives
+   that can't space backwards over records. NOTE: The tape will be
+   spaced backwards over an "accidentally" crossed filemark in any case. */
+#define ST_IN_FILE_POS 0
+
+/* If ST_RECOVERED_WRITE_FATAL is non-zero, recovered errors while writing
+   are considered "hard errors". */
+#define ST_RECOVERED_WRITE_FATAL 0
+
+/* The "guess" for the block size for devices that don't support MODE
+   SENSE. */
+#define ST_DEFAULT_BLOCK 0
+
+/* The minimum tape driver buffer size in kilobytes in fixed block mode.
+   Must be non-zero. */
+#define ST_FIXED_BUFFER_BLOCKS 32
+
+/* Maximum number of scatter/gather segments */
+#define ST_MAX_SG      256
+
+/* The number of scatter/gather segments to allocate at first try (must be
+   smaller or equal to the maximum). */
+#define ST_FIRST_SG    8
+
+/* The size of the first scatter/gather segments (determines the maximum block
+   size for SCSI adapters not supporting scatter/gather). The default is set
+   to try to allocate the buffer as one chunk. */
+#define ST_FIRST_ORDER  5
+
+
+/* The following lines define defaults for properties that can be set
+   separately for each drive using the MTSTOPTIONS ioctl. */
+
+/* If ST_TWO_FM is non-zero, the driver writes two filemarks after a
+   file being written. Some drives can't handle two filemarks at the
+   end of data. */
+#define ST_TWO_FM 0
+
+/* If ST_BUFFER_WRITES is non-zero, writes in fixed block mode are
+   buffered until the driver buffer is full or asynchronous write is
+   triggered. May make detection of End-Of-Medium early enough fail. */
+#define ST_BUFFER_WRITES 1
+
+/* If ST_ASYNC_WRITES is non-zero, the SCSI write command may be started
+   without waiting for it to finish. May cause problems in multiple
+   tape backups. */
+#define ST_ASYNC_WRITES 1
+
+/* If ST_READ_AHEAD is non-zero, blocks are read ahead in fixed block
+   mode. */
+#define ST_READ_AHEAD 1
+
+/* If ST_AUTO_LOCK is non-zero, the drive door is locked at the first
+   read or write command after the device is opened. The door is opened
+   when the device is closed. */
+#define ST_AUTO_LOCK 0
+
+/* If ST_FAST_MTEOM is non-zero, the MTEOM ioctl is done using the
+   direct SCSI command. The file number status is lost but this method
+   is fast with some drives. Otherwise MTEOM is done by spacing over
+   files and the file number status is retained. */
+#define ST_FAST_MTEOM 0
+
+/* If ST_SCSI2LOGICAL is nonzero, the logical block addresses are used for
+   MTIOCPOS and MTSEEK by default. Vendor addresses are used if ST_SCSI2LOGICAL
+   is zero. */
+#define ST_SCSI2LOGICAL 0
+
+/* If ST_SYSV is non-zero, the tape behaves according to the SYS V semantics.
+   The default is BSD semantics. */
+#define ST_SYSV 0
+
+/* If ST_SILI is non-zero, the SILI bit is set when reading in variable block
+   mode and the block size is determined using the residual returned by the HBA. */
+#define ST_SILI 0
+
+/* Time to wait for the drive to become ready if blocking open */
+#define ST_BLOCK_SECONDS     120
+
+#endif