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, 26 insertions, 0 deletions

diff --git a/Documentation/admin-guide/media/c3-isp.dot b/Documentation/admin-guide/media/c3-isp.dot
new file mode 100644
index 000000000..42dc931ee
--- /dev/null
+++ b/Documentation/admin-guide/media/c3-isp.dot
@@ -0,0 +1,26 @@
+digraph board {
+	rankdir=TB
+	n00000001 [label="{{<port0> 0 | <port1> 1} | c3-isp-core\n/dev/v4l-subdev0 | {<port2> 2 | <port3> 3 | <port4> 4 | <port5> 5}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000001:port3 -> n00000008:port0
+	n00000001:port4 -> n0000000b:port0
+	n00000001:port5 -> n0000000e:port0
+	n00000001:port2 -> n00000027
+	n00000008 [label="{{<port0> 0} | c3-isp-resizer0\n/dev/v4l-subdev1 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000008:port1 -> n00000016 [style=bold]
+	n0000000b [label="{{<port0> 0} | c3-isp-resizer1\n/dev/v4l-subdev2 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000000b:port1 -> n0000001a [style=bold]
+	n0000000e [label="{{<port0> 0} | c3-isp-resizer2\n/dev/v4l-subdev3 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000000e:port1 -> n00000023 [style=bold]
+	n00000011 [label="{{<port0> 0} | c3-mipi-adapter\n/dev/v4l-subdev4 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000011:port1 -> n00000001:port0 [style=bold]
+	n00000016 [label="c3-isp-cap0\n/dev/video0", shape=box, style=filled, fillcolor=yellow]
+	n0000001a [label="c3-isp-cap1\n/dev/video1", shape=box, style=filled, fillcolor=yellow]
+	n0000001e [label="{{<port0> 0} | c3-mipi-csi2\n/dev/v4l-subdev5 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000001e:port1 -> n00000011:port0 [style=bold]
+	n00000023 [label="c3-isp-cap2\n/dev/video2", shape=box, style=filled, fillcolor=yellow]
+	n00000027 [label="c3-isp-stats\n/dev/video3", shape=box, style=filled, fillcolor=yellow]
+	n0000002b [label="c3-isp-params\n/dev/video4", shape=box, style=filled, fillcolor=yellow]
+	n0000002b -> n00000001:port1
+	n0000003f [label="{{} | imx290 2-001a\n/dev/v4l-subdev6 | {<port0> 0}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000003f:port0 -> n0000001e:port0 [style=bold]
+}