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, 107 insertions, 0 deletions

diff --git a/Documentation/usb/linux-cdc-acm.inf b/Documentation/usb/linux-cdc-acm.inf
new file mode 100644
index 000000000..f0ffc27d4
--- /dev/null
+++ b/Documentation/usb/linux-cdc-acm.inf
@@ -0,0 +1,107 @@
+; Windows USB CDC ACM Setup File
+
+; Based on INF template which was:
+;     Copyright (c) 2000 Microsoft Corporation
+;     Copyright (c) 2007 Microchip Technology Inc.
+; likely to be covered by the MLPL as found at:
+;    <http://msdn.microsoft.com/en-us/cc300389.aspx#MLPL>.
+; For use only on Windows operating systems.
+
+[Version]
+Signature="$Windows NT$"
+Class=Ports
+ClassGuid={4D36E978-E325-11CE-BFC1-08002BE10318}
+Provider=%Linux%
+DriverVer=11/15/2007,5.1.2600.0
+
+[Manufacturer]
+%Linux%=DeviceList, NTamd64
+
+[DestinationDirs]
+DefaultDestDir=12
+
+
+;------------------------------------------------------------------------------
+;  Windows 2000/XP/Vista-32bit Sections
+;------------------------------------------------------------------------------
+
+[DriverInstall.nt]
+include=mdmcpq.inf
+CopyFiles=DriverCopyFiles.nt
+AddReg=DriverInstall.nt.AddReg
+
+[DriverCopyFiles.nt]
+usbser.sys,,,0x20
+
+[DriverInstall.nt.AddReg]
+HKR,,DevLoader,,*ntkern
+HKR,,NTMPDriver,,USBSER.sys
+HKR,,EnumPropPages32,,"MsPorts.dll,SerialPortPropPageProvider"
+
+[DriverInstall.nt.Services]
+AddService=usbser, 0x00000002, DriverService.nt
+
+[DriverService.nt]
+DisplayName=%SERVICE%
+ServiceType=1
+StartType=3
+ErrorControl=1
+ServiceBinary=%12%\USBSER.sys
+
+;------------------------------------------------------------------------------
+;  Vista-64bit Sections
+;------------------------------------------------------------------------------
+
+[DriverInstall.NTamd64]
+include=mdmcpq.inf
+CopyFiles=DriverCopyFiles.NTamd64
+AddReg=DriverInstall.NTamd64.AddReg
+
+[DriverCopyFiles.NTamd64]
+USBSER.sys,,,0x20
+
+[DriverInstall.NTamd64.AddReg]
+HKR,,DevLoader,,*ntkern
+HKR,,NTMPDriver,,USBSER.sys
+HKR,,EnumPropPages32,,"MsPorts.dll,SerialPortPropPageProvider"
+
+[DriverInstall.NTamd64.Services]
+AddService=usbser, 0x00000002, DriverService.NTamd64
+
+[DriverService.NTamd64]
+DisplayName=%SERVICE%
+ServiceType=1
+StartType=3
+ErrorControl=1
+ServiceBinary=%12%\USBSER.sys
+
+
+;------------------------------------------------------------------------------
+;  Vendor and Product ID Definitions
+;------------------------------------------------------------------------------
+; When developing your USB device, the VID and PID used in the PC side
+; application program and the firmware on the microcontroller must match.
+; Modify the below line to use your VID and PID.  Use the format as shown
+; below.
+; Note: One INF file can be used for multiple devices with different
+;       VID and PIDs.  For each supported device, append
+;       ",USB\VID_xxxx&PID_yyyy" to the end of the line.
+;------------------------------------------------------------------------------
+[SourceDisksFiles]
+[SourceDisksNames]
+[DeviceList]
+%DESCRIPTION%=DriverInstall, USB\VID_0525&PID_A4A7, USB\VID_1D6B&PID_0104&MI_02, USB\VID_1D6B&PID_0106&MI_00
+
+[DeviceList.NTamd64]
+%DESCRIPTION%=DriverInstall, USB\VID_0525&PID_A4A7, USB\VID_1D6B&PID_0104&MI_02, USB\VID_1D6B&PID_0106&MI_00
+
+
+;------------------------------------------------------------------------------
+;  String Definitions
+;------------------------------------------------------------------------------
+;Modify these strings to customize your device
+;------------------------------------------------------------------------------
+[Strings]
+Linux               = "Linux Developer Community"
+DESCRIPTION         = "Gadget Serial"
+SERVICE             = "USB RS-232 Emulation Driver"