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/net/ipv4/fou_nl.c b/net/ipv4/fou_nl.c
new file mode 100644
index 000000000..309d5ba98
--- /dev/null
+++ b/net/ipv4/fou_nl.c
@@ -0,0 +1,49 @@
+// SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)
+/* Do not edit directly, auto-generated from: */
+/*	Documentation/netlink/specs/fou.yaml */
+/* YNL-GEN kernel source */
+/* To regenerate run: tools/net/ynl/ynl-regen.sh */
+
+#include <net/netlink.h>
+#include <net/genetlink.h>
+
+#include "fou_nl.h"
+
+#include <uapi/linux/fou.h>
+
+/* Global operation policy for fou */
+const struct nla_policy fou_nl_policy[FOU_ATTR_IFINDEX + 1] = {
+	[FOU_ATTR_PORT] = { .type = NLA_BE16, },
+	[FOU_ATTR_AF] = { .type = NLA_U8, },
+	[FOU_ATTR_IPPROTO] = NLA_POLICY_MIN(NLA_U8, 1),
+	[FOU_ATTR_TYPE] = { .type = NLA_U8, },
+	[FOU_ATTR_REMCSUM_NOPARTIAL] = { .type = NLA_FLAG, },
+	[FOU_ATTR_LOCAL_V4] = { .type = NLA_U32, },
+	[FOU_ATTR_LOCAL_V6] = NLA_POLICY_EXACT_LEN(16),
+	[FOU_ATTR_PEER_V4] = { .type = NLA_U32, },
+	[FOU_ATTR_PEER_V6] = NLA_POLICY_EXACT_LEN(16),
+	[FOU_ATTR_PEER_PORT] = { .type = NLA_BE16, },
+	[FOU_ATTR_IFINDEX] = { .type = NLA_S32, },
+};
+
+/* Ops table for fou */
+const struct genl_small_ops fou_nl_ops[3] = {
+	{
+		.cmd		= FOU_CMD_ADD,
+		.validate	= GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
+		.doit		= fou_nl_add_doit,
+		.flags		= GENL_ADMIN_PERM,
+	},
+	{
+		.cmd		= FOU_CMD_DEL,
+		.validate	= GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
+		.doit		= fou_nl_del_doit,
+		.flags		= GENL_ADMIN_PERM,
+	},
+	{
+		.cmd		= FOU_CMD_GET,
+		.validate	= GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
+		.doit		= fou_nl_get_doit,
+		.dumpit		= fou_nl_get_dumpit,
+	},
+};