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, 52 insertions, 0 deletions

diff --git a/include/net/ife.h b/include/net/ife.h
new file mode 100644
index 000000000..7e2538d85
--- /dev/null
+++ b/include/net/ife.h
@@ -0,0 +1,52 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __NET_IFE_H
+#define __NET_IFE_H
+
+#include <linux/etherdevice.h>
+#include <linux/rtnetlink.h>
+#include <uapi/linux/ife.h>
+
+#if IS_ENABLED(CONFIG_NET_IFE)
+
+void *ife_encode(struct sk_buff *skb, u16 metalen);
+void *ife_decode(struct sk_buff *skb, u16 *metalen);
+
+void *ife_tlv_meta_decode(void *skbdata, const void *ifehdr_end, u16 *attrtype,
+			  u16 *dlen, u16 *totlen);
+int ife_tlv_meta_encode(void *skbdata, u16 attrtype, u16 dlen,
+			const void *dval);
+
+void *ife_tlv_meta_next(void *skbdata);
+
+#else
+
+static inline void *ife_encode(struct sk_buff *skb, u16 metalen)
+{
+	return NULL;
+}
+
+static inline void *ife_decode(struct sk_buff *skb, u16 *metalen)
+{
+	return NULL;
+}
+
+static inline void *ife_tlv_meta_decode(void *skbdata, u16 *attrtype, u16 *dlen,
+					u16 *totlen)
+{
+	return NULL;
+}
+
+static inline int ife_tlv_meta_encode(void *skbdata, u16 attrtype, u16 dlen,
+			const void *dval)
+{
+	return 0;
+}
+
+static inline void *ife_tlv_meta_next(void *skbdata)
+{
+	return NULL;
+}
+
+#endif
+
+#endif /* __NET_IFE_H */