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, 59 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-class-rapidio b/Documentation/ABI/testing/sysfs-class-rapidio
new file mode 100644
index 000000000..81e091455
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-rapidio
@@ -0,0 +1,59 @@
+What:		/sys/class/rapidio_port
+Description:
+		On-chip RapidIO controllers and PCIe-to-RapidIO bridges
+		(referenced as "Master Port" or "mport") are presented in sysfs
+		as the special class of devices: "rapidio_port".
+		The /sys/class/rapidio_port subdirectory contains individual
+		subdirectories named as "rapidioN" where N = mport ID registered
+		with RapidIO subsystem.
+
+		NOTE: An mport ID is not a RapidIO destination ID assigned to a
+		given local mport device.
+
+What:		/sys/class/rapidio_port/rapidio<N>/sys_size
+Date:		Apr, 2014
+KernelVersion:	v3.15
+Contact:	Matt Porter <mporter@kernel.crashing.org>,
+		Alexandre Bounine <alexandre.bounine@idt.com>
+Description:
+		(RO) reports RapidIO common transport system size:
+
+		0 = small (8-bit destination ID, max. 256 devices),
+
+		1 = large (16-bit destination ID, max. 65536 devices).
+
+What:		/sys/class/rapidio_port/rapidio<N>/port_destid
+Date:		Apr, 2014
+KernelVersion:	v3.15
+Contact:	Matt Porter <mporter@kernel.crashing.org>,
+		Alexandre Bounine <alexandre.bounine@idt.com>
+Description:
+
+(RO) reports RapidIO destination ID assigned to the given
+RapidIO mport device. If value 0xFFFFFFFF is returned this means
+that no valid destination ID have been assigned to the mport
+(yet). Normally, before enumeration/discovery have been executed
+only fabric enumerating mports have a valid destination ID
+assigned to them using "hdid=..." rapidio module parameter.
+
+After enumeration or discovery was performed for a given mport device,
+the corresponding subdirectory will also contain subdirectories for each
+child RapidIO device connected to the mport.
+
+The example below shows mport device subdirectory with several child RapidIO
+devices attached to it::
+
+    [rio@rapidio ~]$ ls /sys/class/rapidio_port/rapidio0/ -l
+    total 0
+    drwxr-xr-x 3 root root    0 Feb 11 15:10 00:e:0001
+    drwxr-xr-x 3 root root    0 Feb 11 15:10 00:e:0004
+    drwxr-xr-x 3 root root    0 Feb 11 15:10 00:e:0007
+    drwxr-xr-x 3 root root    0 Feb 11 15:10 00:s:0002
+    drwxr-xr-x 3 root root    0 Feb 11 15:10 00:s:0003
+    drwxr-xr-x 3 root root    0 Feb 11 15:10 00:s:0005
+    lrwxrwxrwx 1 root root    0 Feb 11 15:11 device -> ../../../0000:01:00.0
+    -r--r--r-- 1 root root 4096 Feb 11 15:11 port_destid
+    drwxr-xr-x 2 root root    0 Feb 11 15:11 power
+    lrwxrwxrwx 1 root root    0 Feb 11 15:04 subsystem -> ../../../../../../class/rapidio_port
+    -r--r--r-- 1 root root 4096 Feb 11 15:11 sys_size
+    -rw-r--r-- 1 root root 4096 Feb 11 15:04 uevent