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, 91 insertions, 0 deletions

diff --git a/include/trace/events/fib6.h b/include/trace/events/fib6.h
new file mode 100644
index 000000000..8d22b2e98
--- /dev/null
+++ b/include/trace/events/fib6.h
@@ -0,0 +1,91 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM fib6
+
+#if !defined(_TRACE_FIB6_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_FIB6_H
+
+#include <linux/in6.h>
+#include <net/flow.h>
+#include <net/ip6_fib.h>
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(fib6_table_lookup,
+
+	TP_PROTO(const struct net *net, const struct fib6_result *res,
+		 struct fib6_table *table, const struct flowi6 *flp),
+
+	TP_ARGS(net, res, table, flp),
+
+	TP_STRUCT__entry(
+		__field(	u32,	tb_id		)
+		__field(	int,	err		)
+		__field(	int,	oif		)
+		__field(	int,	iif		)
+		__field(	u32,	flowlabel	)
+		__field(	__u8,	tos		)
+		__field(	__u8,	scope		)
+		__field(	__u8,	flags		)
+		__array(	__u8,	src,	16	)
+		__array(	__u8,	dst,	16	)
+		__field(        u16,	sport		)
+		__field(        u16,	dport		)
+		__field(        u8,	proto		)
+		__field(        u8,	rt_type		)
+		__array(		char,	name,	IFNAMSIZ )
+		__array(		__u8,	gw,	16	 )
+	),
+
+	TP_fast_assign(
+		struct in6_addr *in6;
+
+		__entry->tb_id = table->tb6_id;
+		__entry->err = ip6_rt_type_to_error(res->fib6_type);
+		__entry->oif = flp->flowi6_oif;
+		__entry->iif = flp->flowi6_iif;
+		__entry->flowlabel = ntohl(flowi6_get_flowlabel(flp));
+		__entry->tos = ip6_tclass(flp->flowlabel);
+		__entry->scope = flp->flowi6_scope;
+		__entry->flags = flp->flowi6_flags;
+
+		in6 = (struct in6_addr *)__entry->src;
+		*in6 = flp->saddr;
+
+		in6 = (struct in6_addr *)__entry->dst;
+		*in6 = flp->daddr;
+
+		__entry->proto = flp->flowi6_proto;
+		if (__entry->proto == IPPROTO_TCP ||
+		    __entry->proto == IPPROTO_UDP) {
+			__entry->sport = ntohs(flp->fl6_sport);
+			__entry->dport = ntohs(flp->fl6_dport);
+		} else {
+			__entry->sport = 0;
+			__entry->dport = 0;
+		}
+
+		if (res->nh && res->nh->fib_nh_dev) {
+			strscpy(__entry->name, res->nh->fib_nh_dev->name, IFNAMSIZ);
+		} else {
+			strcpy(__entry->name, "-");
+		}
+		if (res->f6i == net->ipv6.fib6_null_entry) {
+			in6 = (struct in6_addr *)__entry->gw;
+			*in6 = in6addr_any;
+		} else if (res->nh) {
+			in6 = (struct in6_addr *)__entry->gw;
+			*in6 = res->nh->fib_nh_gw6;
+		}
+	),
+
+	TP_printk("table %3u oif %d iif %d proto %u %pI6c/%u -> %pI6c/%u flowlabel %#x tos %d scope %d flags %x ==> dev %s gw %pI6c err %d",
+		  __entry->tb_id, __entry->oif, __entry->iif, __entry->proto,
+		  __entry->src, __entry->sport, __entry->dst, __entry->dport,
+		  __entry->flowlabel, __entry->tos, __entry->scope,
+		  __entry->flags, __entry->name, __entry->gw, __entry->err)
+);
+
+#endif /* _TRACE_FIB6_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>