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, 48 insertions, 0 deletions

diff --git a/net/ipv6/exthdrs_offload.c b/net/ipv6/exthdrs_offload.c
new file mode 100644
index 000000000..4c00398f4
--- /dev/null
+++ b/net/ipv6/exthdrs_offload.c
@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *	IPV6 GSO/GRO offload support
+ *	Linux INET6 implementation
+ *
+ *      IPV6 Extension Header GSO/GRO support
+ */
+#include <net/protocol.h>
+#include "ip6_offload.h"
+
+static const struct net_offload rthdr_offload = {
+	.flags		=	INET6_PROTO_GSO_EXTHDR,
+};
+
+static const struct net_offload dstopt_offload = {
+	.flags		=	INET6_PROTO_GSO_EXTHDR,
+};
+
+static const struct net_offload hbh_offload = {
+	.flags		=	INET6_PROTO_GSO_EXTHDR,
+};
+
+int __init ipv6_exthdrs_offload_init(void)
+{
+	int ret;
+
+	ret = inet6_add_offload(&rthdr_offload, IPPROTO_ROUTING);
+	if (ret)
+		goto out;
+
+	ret = inet6_add_offload(&dstopt_offload, IPPROTO_DSTOPTS);
+	if (ret)
+		goto out_rt;
+
+	ret = inet6_add_offload(&hbh_offload, IPPROTO_HOPOPTS);
+	if (ret)
+		goto out_dstopts;
+
+out:
+	return ret;
+
+out_dstopts:
+	inet6_del_offload(&dstopt_offload, IPPROTO_DSTOPTS);
+
+out_rt:
+	inet6_del_offload(&rthdr_offload, IPPROTO_ROUTING);
+	goto out;
+}