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, 90 insertions, 0 deletions

diff --git a/include/net/pfcp.h b/include/net/pfcp.h
new file mode 100644
index 000000000..639553797
--- /dev/null
+++ b/include/net/pfcp.h
@@ -0,0 +1,90 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _PFCP_H_
+#define _PFCP_H_
+
+#include <uapi/linux/if_ether.h>
+#include <net/dst_metadata.h>
+#include <linux/netdevice.h>
+#include <uapi/linux/ipv6.h>
+#include <net/udp_tunnel.h>
+#include <uapi/linux/udp.h>
+#include <uapi/linux/ip.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/bits.h>
+
+#define PFCP_PORT 8805
+
+/* PFCP protocol header */
+struct pfcphdr {
+	u8	flags;
+	u8	message_type;
+	__be16	message_length;
+};
+
+/* PFCP header flags */
+#define PFCP_SEID_FLAG		BIT(0)
+#define PFCP_MP_FLAG		BIT(1)
+
+#define PFCP_VERSION_MASK	GENMASK(4, 0)
+
+#define PFCP_HLEN (sizeof(struct udphdr) + sizeof(struct pfcphdr))
+
+/* PFCP node related messages */
+struct pfcphdr_node {
+	u8	seq_number[3];
+	u8	reserved;
+};
+
+/* PFCP session related messages */
+struct pfcphdr_session {
+	__be64	seid;
+	u8	seq_number[3];
+#ifdef __LITTLE_ENDIAN_BITFIELD
+	u8	message_priority:4,
+		reserved:4;
+#elif defined(__BIG_ENDIAN_BITFIELD)
+	u8	reserved:4,
+		message_priority:4;
+#else
+#error "Please fix <asm/byteorder>"
+#endif
+};
+
+struct pfcp_metadata {
+	u8 type;
+	__be64 seid;
+} __packed;
+
+enum {
+	PFCP_TYPE_NODE		= 0,
+	PFCP_TYPE_SESSION	= 1,
+};
+
+#define PFCP_HEADROOM (sizeof(struct iphdr) + sizeof(struct udphdr) + \
+		       sizeof(struct pfcphdr) + sizeof(struct ethhdr))
+#define PFCP6_HEADROOM (sizeof(struct ipv6hdr) + sizeof(struct udphdr) + \
+			sizeof(struct pfcphdr) + sizeof(struct ethhdr))
+
+static inline struct pfcphdr *pfcp_hdr(struct sk_buff *skb)
+{
+	return (struct pfcphdr *)(udp_hdr(skb) + 1);
+}
+
+static inline struct pfcphdr_node *pfcp_hdr_node(struct sk_buff *skb)
+{
+	return (struct pfcphdr_node *)(pfcp_hdr(skb) + 1);
+}
+
+static inline struct pfcphdr_session *pfcp_hdr_session(struct sk_buff *skb)
+{
+	return (struct pfcphdr_session *)(pfcp_hdr(skb) + 1);
+}
+
+static inline bool netif_is_pfcp(const struct net_device *dev)
+{
+	return dev->rtnl_link_ops &&
+	       !strcmp(dev->rtnl_link_ops->kind, "pfcp");
+}
+
+#endif