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, 137 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-class-rc b/Documentation/ABI/testing/sysfs-class-rc
new file mode 100644
index 000000000..84e46d70d
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-rc
@@ -0,0 +1,137 @@
+What:		/sys/class/rc/
+Date:		Apr 2010
+KernelVersion:	2.6.35
+Contact:	Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
+Description:
+		The rc/ class sub-directory belongs to the Remote Controller
+		core and provides a sysfs interface for configuring infrared
+		remote controller receivers.
+
+What:		/sys/class/rc/rc<N>/
+Date:		Apr 2010
+KernelVersion:	2.6.35
+Contact:	Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
+Description:
+		A /sys/class/rc/rcN directory is created for each remote
+		control receiver device where N is the number of the receiver.
+
+What:		/sys/class/rc/rc<N>/protocols
+Date:		Jun 2010
+KernelVersion:	2.6.36
+Contact:	Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
+Description:
+		Reading this file returns a list of available protocols,
+		something like::
+
+		    "rc5 [rc6] nec jvc [sony]"
+
+		Enabled protocols are shown in [] brackets.
+
+		Writing "+proto" will add a protocol to the list of enabled
+		protocols.
+
+		Writing "-proto" will remove a protocol from the list of enabled
+		protocols.
+
+		Writing "proto" will enable only "proto".
+
+		Writing "none" will disable all protocols.
+
+		Write fails with EINVAL if an invalid protocol combination or
+		unknown protocol name is used.
+
+What:		/sys/class/rc/rc<N>/filter
+Date:		Jan 2014
+KernelVersion:	3.15
+Contact:	Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
+Description:
+		Sets the scancode filter expected value.
+
+		Use in combination with /sys/class/rc/rcN/filter_mask to set the
+		expected value of the bits set in the filter mask.
+		If the hardware supports it then scancodes which do not match
+		the filter will be ignored. Otherwise the write will fail with
+		an error.
+
+		This value may be reset to 0 if the current protocol is altered.
+
+What:		/sys/class/rc/rc<N>/filter_mask
+Date:		Jan 2014
+KernelVersion:	3.15
+Contact:	Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
+Description:
+		Sets the scancode filter mask of bits to compare.
+		Use in combination with /sys/class/rc/rcN/filter to set the bits
+		of the scancode which should be compared against the expected
+		value. A value of 0 disables the filter to allow all valid
+		scancodes to be processed.
+
+		If the hardware supports it then scancodes which do not match
+		the filter will be ignored. Otherwise the write will fail with
+		an error.
+
+		This value may be reset to 0 if the current protocol is altered.
+
+What:		/sys/class/rc/rc<N>/wakeup_protocols
+Date:		Feb 2017
+KernelVersion:	4.11
+Contact:	Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
+Description:
+		Reading this file returns a list of available protocols to use
+		for the wakeup filter, something like::
+
+		    "rc-5 nec nec-x rc-6-0 rc-6-6a-24 [rc-6-6a-32] rc-6-mce"
+
+		Note that protocol variants are listed, so "nec", "sony",
+		"rc-5", "rc-6" have their different bit length encodings
+		listed if available.
+
+		The enabled wakeup protocol is shown in [] brackets.
+
+		Only one protocol can be selected at a time.
+
+		Writing "proto" will use "proto" for wakeup events.
+
+		Writing "none" will disable wakeup.
+
+		Write fails with EINVAL if an invalid protocol combination or
+		unknown protocol name is used, or if wakeup is not supported by
+		the hardware.
+
+What:		/sys/class/rc/rc<N>/wakeup_filter
+Date:		Jan 2014
+KernelVersion:	3.15
+Contact:	Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
+Description:
+		Sets the scancode wakeup filter expected value.
+
+		Use in combination with /sys/class/rc/rcN/wakeup_filter_mask to
+		set the expected value of the bits set in the wakeup filter mask
+		to trigger a system wake event.
+
+		If the hardware supports it and wakeup_filter_mask is not 0 then
+		scancodes which match the filter will wake the system from e.g.
+		suspend to RAM or power off.
+
+		Otherwise the write will fail with an error.
+
+		This value may be reset to 0 if the wakeup protocol is altered.
+
+What:		/sys/class/rc/rc<N>/wakeup_filter_mask
+Date:		Jan 2014
+KernelVersion:	3.15
+Contact:	Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
+Description:
+		Sets the scancode wakeup filter mask of bits to compare.
+
+		Use in combination with /sys/class/rc/rcN/wakeup_filter to set
+		the bits of the scancode which should be compared against the
+		expected value to trigger a system wake event.
+
+		If the hardware supports it and wakeup_filter_mask is not 0 then
+		scancodes which match the filter will wake the system from e.g.
+		suspend to RAM or power off.
+
+		Otherwise the write will fail with an error.
+
+		This value may be reset to 0 if the wakeup protocol is altered.