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, 75 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-class-net-phydev b/Documentation/ABI/testing/sysfs-class-net-phydev
new file mode 100644
index 000000000..31615c59b
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-net-phydev
@@ -0,0 +1,75 @@
+What:		/sys/class/mdio_bus/<bus>/<device>/attached_dev
+Date:		May 2017
+KernelVersion:	4.13
+Contact:	netdev@vger.kernel.org
+Description:
+		Symbolic link to the network device this PHY device is
+		attached to.
+
+What:		/sys/class/mdio_bus/<bus>/<device>/phy_has_fixups
+Date:		February 2014
+KernelVersion:	3.15
+Contact:	netdev@vger.kernel.org
+Description:
+		This attribute contains the boolean value whether a given PHY
+		device has had any "fixup" workaround running on it, encoded as
+		a boolean. This information is provided to help troubleshooting
+		PHY configurations.
+
+What:		/sys/class/mdio_bus/<bus>/<device>/phy_id
+Date:		November 2012
+KernelVersion:	3.8
+Contact:	netdev@vger.kernel.org
+Description:
+		This attribute contains the 32-bit PHY Identifier as reported
+		by the device during bus enumeration, encoded in hexadecimal.
+		This ID is used to match the device with the appropriate
+		driver.
+
+What:		/sys/class/mdio_bus/<bus>/<device>/c45_phy_ids/mmd<n>_device_id
+Date:		June 2025
+KernelVersion:	6.17
+Contact:	netdev@vger.kernel.org
+Description:
+		This attribute contains the 32-bit PHY Identifier as reported
+		by the device during bus enumeration, encoded in hexadecimal.
+		These C45 IDs are used to match the device with the appropriate
+		driver. These files are invisible to the C22 device.
+
+What:		/sys/class/mdio_bus/<bus>/<device>/phy_interface
+Date:		February 2014
+KernelVersion:	3.15
+Contact:	netdev@vger.kernel.org
+Description:
+		This attribute contains the PHY interface as configured by the
+		Ethernet driver during bus enumeration, encoded in string.
+		This interface mode is used to configure the Ethernet MAC with the
+		appropriate mode for its data lines to the PHY hardware.
+
+		Possible values are:
+
+		<empty> (not available), mii, gmii, sgmii, tbi, rev-mii,
+		rmii, rgmii, rgmii-id, rgmii-rxid, rgmii-txid, rtbi, smii
+		xgmii, moca, qsgmii, trgmii, 1000base-x, 2500base-x, rxaui,
+		xaui, 10gbase-kr, unknown
+
+What:		/sys/class/mdio_bus/<bus>/<device>/phy_standalone
+Date:		May 2019
+KernelVersion:	5.3
+Contact:	netdev@vger.kernel.org
+Description:
+		Boolean value indicating whether the PHY device is used in
+		standalone mode, without a net_device associated, by PHYLINK.
+		Attribute created only when this is the case.
+
+What:		/sys/class/mdio_bus/<bus>/<device>/phy_dev_flags
+Date:		March 2021
+KernelVersion:	5.13
+Contact:	netdev@vger.kernel.org
+Description:
+		32-bit hexadecimal number representing a bit mask of the
+		configuration bits passed from the consumer of the PHY
+		(Ethernet MAC, switch, etc.) to the PHY driver. The flags are
+		only used internally by the kernel and their placement are
+		not meant to be stable across kernel versions. This is intended
+		for facilitating the debugging of PHY drivers.