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, 35 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-class-net-grcan b/Documentation/ABI/testing/sysfs-class-net-grcan
new file mode 100644
index 000000000..f418c92ca
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-net-grcan
@@ -0,0 +1,35 @@
+
+What:		/sys/class/net/<iface>/grcan/enable0
+Date:		October 2012
+KernelVersion:	3.8
+Contact:	Andreas Larsson <andreas@gaisler.com>
+Description:
+		Hardware configuration of physical interface 0. This file reads
+		and writes the "Enable 0" bit of the configuration register.
+		Possible values: 0 or 1. See the GRCAN chapter of the GRLIB IP
+		core library documentation for details. The default value is 0
+		or set by the module parameter grcan.enable0 and can be read at
+		/sys/module/grcan/parameters/enable0.
+
+What:		/sys/class/net/<iface>/grcan/enable1
+Date:		October 2012
+KernelVersion:	3.8
+Contact:	Andreas Larsson <andreas@gaisler.com>
+Description:
+		Hardware configuration of physical interface 1. This file reads
+		and writes the "Enable 1" bit of the configuration register.
+		Possible values: 0 or 1. See the GRCAN chapter of the GRLIB IP
+		core library documentation for details. The default value is 0
+		or set by the module parameter grcan.enable1 and can be read at
+		/sys/module/grcan/parameters/enable1.
+
+What:		/sys/class/net/<iface>/grcan/select
+Date:		October 2012
+KernelVersion:	3.8
+Contact:	Andreas Larsson <andreas@gaisler.com>
+Description:
+		Configuration of which physical interface to be used. Possible
+		values: 0 or 1. See the GRCAN chapter of the GRLIB IP core
+		library documentation for details. The default value is 0 or is
+		set by the module parameter grcan.select and can be read at
+		/sys/module/grcan/parameters/select.