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, 50 insertions, 0 deletions

diff --git a/Documentation/driver-api/firewire.rst b/Documentation/driver-api/firewire.rst
new file mode 100644
index 000000000..28a32410f
--- /dev/null
+++ b/Documentation/driver-api/firewire.rst
@@ -0,0 +1,50 @@
+===========================================
+Firewire (IEEE 1394) driver Interface Guide
+===========================================
+
+Introduction and Overview
+=========================
+
+The Linux FireWire subsystem adds some interfaces into the Linux system to
+ use/maintain+any resource on IEEE 1394 bus.
+
+The main purpose of these interfaces is to access address space on each node
+on IEEE 1394 bus by ISO/IEC 13213 (IEEE 1212) procedure, and to control
+isochronous resources on the bus by IEEE 1394 procedure.
+
+Two types of interfaces are added, according to consumers of the interface. A
+set of userspace interfaces is available via `firewire character devices`. A set
+of kernel interfaces is available via exported symbols in `firewire-core` module.
+
+Firewire char device data structures
+====================================
+
+.. include:: ../ABI/stable/firewire-cdev
+    :literal:
+
+.. kernel-doc:: include/uapi/linux/firewire-cdev.h
+    :internal:
+
+Firewire device probing and sysfs interfaces
+============================================
+
+.. include:: ../ABI/stable/sysfs-bus-firewire
+    :literal:
+
+.. kernel-doc:: drivers/firewire/core-device.c
+    :export:
+
+Firewire core transaction interfaces
+====================================
+
+.. kernel-doc:: drivers/firewire/core-transaction.c
+    :export:
+
+Firewire Isochronous I/O interfaces
+===================================
+
+.. kernel-doc:: include/linux/firewire.h
+   :functions: fw_iso_context_schedule_flush_completions
+.. kernel-doc:: drivers/firewire/core-iso.c
+   :export:
+