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, 49 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-driver-xdata b/Documentation/ABI/testing/sysfs-driver-xdata
new file mode 100644
index 000000000..f574e8e6d
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-driver-xdata
@@ -0,0 +1,49 @@
+What:		/sys/class/misc/drivers/dw-xdata-pcie.<device>/write
+Date:		April 2021
+KernelVersion:	5.13
+Contact:	Gustavo Pimentel <gustavo.pimentel@synopsys.com>
+Description:	Allows the user to enable the PCIe traffic generator which
+		will create write TLPs frames - from the Root Complex to the
+		Endpoint direction or to disable the PCIe traffic generator
+		in all directions.
+
+		Write y/1/on to enable, n/0/off to disable
+
+		Usage e.g.
+		 echo 1 > /sys/class/misc/dw-xdata-pcie.<device>/write
+		or
+		 echo 0 > /sys/class/misc/dw-xdata-pcie.<device>/write
+
+		The user can read the current PCIe link throughput generated
+		through this generator in MB/s.
+
+		Usage e.g.
+		 cat /sys/class/misc/dw-xdata-pcie.<device>/write
+		 204
+
+		The file is read and write.
+
+What:		/sys/class/misc/dw-xdata-pcie.<device>/read
+Date:		April 2021
+KernelVersion:	5.13
+Contact:	Gustavo Pimentel <gustavo.pimentel@synopsys.com>
+Description:	Allows the user to enable the PCIe traffic generator which
+		will create read TLPs frames - from the Endpoint to the Root
+		Complex direction or to disable the PCIe traffic generator
+                in all directions.
+
+		Write y/1/on to enable, n/0/off to disable
+
+		Usage e.g.
+		 echo 1 > /sys/class/misc/dw-xdata-pcie.<device>/read
+		or
+		 echo 0 > /sys/class/misc/dw-xdata-pcie.<device>/read
+
+		The user can read the current PCIe link throughput generated
+		through this generator in MB/s.
+
+		Usage e.g.
+		 cat /sys/class/misc/dw-xdata-pcie.<device>/read
+		 199
+
+		The file is read and write.