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, 37 insertions, 0 deletions

diff --git a/net/atm/Kconfig b/net/atm/Kconfig
new file mode 100644
index 000000000..dfdc3a855
--- /dev/null
+++ b/net/atm/Kconfig
@@ -0,0 +1,37 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Asynchronous Transfer Mode (ATM)
+#
+
+config ATM
+	tristate "Asynchronous Transfer Mode (ATM)"
+	help
+	  ATM is a high-speed networking technology for Local Area Networks
+	  and Wide Area Networks.  It uses a fixed packet size and is
+	  connection oriented, allowing for the negotiation of minimum
+	  bandwidth requirements.
+
+	  In order to participate in an ATM network, your Linux box needs an
+	  ATM networking card. If you have that, say Y here and to the driver
+	  of your ATM card below.
+
+	  Note that you need a set of user-space programs to actually make use
+	  of ATM.  See the file <file:Documentation/networking/atm.rst> for
+	  further details.
+
+config ATM_BR2684
+	tristate "RFC1483/2684 Bridged protocols"
+	depends on ATM && INET
+	help
+	  ATM PVCs can carry ethernet PDUs according to RFC2684 (formerly 1483)
+	  This device will act like an ethernet from the kernels point of view,
+	  with the traffic being carried by ATM PVCs (currently 1 PVC/device).
+	  This is sometimes used over DSL lines.  If in doubt, say N.
+
+config ATM_BR2684_IPFILTER
+	bool "Per-VC IP filter kludge"
+	depends on ATM_BR2684
+	help
+	  This is an experimental mechanism for users who need to terminate a
+	  large number of IP-only vcc's.  Do not enable this unless you are sure
+	  you know what you are doing.