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, 165 insertions, 0 deletions

diff --git a/drivers/i2c/Kconfig b/drivers/i2c/Kconfig
new file mode 100644
index 000000000..c232054fd
--- /dev/null
+++ b/drivers/i2c/Kconfig
@@ -0,0 +1,165 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# I2C subsystem configuration
+#
+
+menu "I2C support"
+
+config I2C
+	tristate "I2C support"
+	select RT_MUTEXES
+	select IRQ_DOMAIN
+	help
+	  I2C (pronounce: I-squared-C) is a slow serial bus protocol used in
+	  many micro controller applications and developed by Philips.  SMBus,
+	  or System Management Bus is a subset of the I2C protocol.  More
+	  information is contained in the directory <file:Documentation/i2c/>,
+	  especially in the file called "summary" there.
+
+	  Both I2C and SMBus are supported here. You will need this for
+	  hardware sensors support, and also for Video For Linux support.
+
+	  If you want I2C support, you should say Y here and also to the
+	  specific driver for your bus adapter(s) below.
+
+	  This I2C support can also be built as a module.  If so, the module
+	  will be called i2c-core.
+
+config ACPI_I2C_OPREGION
+	bool "ACPI I2C Operation region support"
+	depends on I2C=y && ACPI
+	default y
+	help
+	  Say Y here if you want to enable ACPI I2C operation region support.
+	  Operation Regions allow firmware (BIOS) code to access I2C slave devices,
+	  such as smart batteries through an I2C host controller driver.
+
+if I2C
+
+config I2C_BOARDINFO
+	bool
+	default y
+
+config I2C_CHARDEV
+	tristate "I2C device interface"
+	help
+	  Say Y here to use i2c-* device files, usually found in the /dev
+	  directory on your system.  They make it possible to have user-space
+	  programs use the I2C bus.  Information on how to do this is
+	  contained in the file <file:Documentation/i2c/dev-interface.rst>.
+
+	  This support is also available as a module.  If so, the module 
+	  will be called i2c-dev.
+
+config I2C_MUX
+	tristate "I2C bus multiplexing support"
+	help
+	  Say Y here if you want the I2C core to support the ability to
+	  handle multiplexed I2C bus topologies, by presenting each
+	  multiplexed segment as a I2C adapter.
+
+	  This support is also available as a module.  If so, the module
+	  will be called i2c-mux.
+
+source "drivers/i2c/muxes/Kconfig"
+
+config I2C_ATR
+	tristate "I2C Address Translator (ATR) support" if COMPILE_TEST
+	help
+	  Enable support for I2C Address Translator (ATR) chips.
+
+	  An ATR allows accessing multiple I2C busses from a single
+	  physical bus via address translation instead of bus selection as
+	  i2c-muxes do.
+
+config I2C_HELPER_AUTO
+	bool "Autoselect pertinent helper modules"
+	default y
+	help
+	  Some I2C bus drivers require so-called "I2C algorithm" modules
+	  to work. These are basically software-only abstractions of generic
+	  I2C interfaces. This option will autoselect them so that you don't
+	  have to care.
+
+	  Unselect this only if you need to enable additional helper
+	  modules, for example for use with external I2C bus drivers.
+
+	  In doubt, say Y.
+
+config I2C_SMBUS
+	tristate "SMBus-specific protocols" if !I2C_HELPER_AUTO
+	help
+	  Say Y here if you want support for SMBus extensions to the I2C
+	  specification. At the moment, two extensions are supported:
+	  the SMBus Alert protocol and the SMBus Host Notify protocol.
+
+	  This support is also available as a module.  If so, the module
+	  will be called i2c-smbus.
+
+source "drivers/i2c/algos/Kconfig"
+source "drivers/i2c/busses/Kconfig"
+
+config I2C_STUB
+	tristate "I2C/SMBus Test Stub"
+	depends on m
+	help
+	  This module may be useful to developers of SMBus client drivers,
+	  especially for certain kinds of sensor chips.
+
+	  If you do build this module, be sure to read the notes and warnings
+	  in <file:Documentation/i2c/i2c-stub.rst>.
+
+	  If you don't know what to do here, definitely say N.
+
+config I2C_SLAVE
+	bool "I2C slave support"
+	help
+	  This enables Linux to act as an I2C slave device. Note that your I2C
+	  bus master driver also needs to support this functionality. Please
+	  read Documentation/i2c/slave-interface.rst for further details.
+
+if I2C_SLAVE
+
+config I2C_SLAVE_EEPROM
+	tristate "I2C eeprom slave driver"
+	help
+	  This backend makes Linux behave like an I2C EEPROM. Please read
+	  Documentation/i2c/slave-eeprom-backend.rst for further details.
+
+config I2C_SLAVE_TESTUNIT
+	tristate "I2C testunit driver"
+	help
+	  This backend can be used to trigger test cases for I2C bus masters
+	  which require a remote device with certain capabilities, e.g.
+	  multi-master, SMBus Host Notify, etc. Please read
+	  Documentation/i2c/slave-testunit-backend.rst for further details.
+
+endif
+
+config I2C_DEBUG_CORE
+	bool "I2C Core debugging messages"
+	help
+	  Say Y here if you want the I2C core to produce a bunch of debug
+	  messages to the system log.  Select this if you are having a
+	  problem with I2C support and want to see more of what is going on.
+
+config I2C_DEBUG_ALGO
+	bool "I2C Algorithm debugging messages"
+	help
+	  Say Y here if you want the I2C algorithm drivers to produce a bunch
+	  of debug messages to the system log.  Select this if you are having
+	  a problem with I2C support and want to see more of what is going
+	  on.
+
+config I2C_DEBUG_BUS
+	bool "I2C Bus debugging messages"
+	depends on HAS_IOMEM
+	help
+	  Say Y here if you want the I2C bus drivers to produce a bunch of
+	  debug messages to the system log.  Select this if you are having
+	  a problem with I2C support and want to see more of what is going
+	  on.
+
+endif # I2C
+
+endmenu