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, 107 insertions, 0 deletions

diff --git a/include/trace/events/nbd.h b/include/trace/events/nbd.h
new file mode 100644
index 000000000..390d98a05
--- /dev/null
+++ b/include/trace/events/nbd.h
@@ -0,0 +1,107 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM nbd
+
+#if !defined(_TRACE_NBD_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_NBD_H
+
+#include <linux/tracepoint.h>
+
+DECLARE_EVENT_CLASS(nbd_transport_event,
+
+	TP_PROTO(struct request *req, u64 handle),
+
+	TP_ARGS(req, handle),
+
+	TP_STRUCT__entry(
+		__field(struct request *, req)
+		__field(u64, handle)
+	),
+
+	TP_fast_assign(
+		__entry->req = req;
+		__entry->handle = handle;
+	),
+
+	TP_printk(
+		"nbd transport event: request %p, handle 0x%016llx",
+		__entry->req,
+		__entry->handle
+	)
+);
+
+DEFINE_EVENT(nbd_transport_event, nbd_header_sent,
+
+	TP_PROTO(struct request *req, u64 handle),
+
+	TP_ARGS(req, handle)
+);
+
+DEFINE_EVENT(nbd_transport_event, nbd_payload_sent,
+
+	TP_PROTO(struct request *req, u64 handle),
+
+	TP_ARGS(req, handle)
+);
+
+DEFINE_EVENT(nbd_transport_event, nbd_header_received,
+
+	TP_PROTO(struct request *req, u64 handle),
+
+	TP_ARGS(req, handle)
+);
+
+DEFINE_EVENT(nbd_transport_event, nbd_payload_received,
+
+	TP_PROTO(struct request *req, u64 handle),
+
+	TP_ARGS(req, handle)
+);
+
+DECLARE_EVENT_CLASS(nbd_send_request,
+
+	TP_PROTO(struct nbd_request *nbd_request, int index,
+		 struct request *rq),
+
+	TP_ARGS(nbd_request, index, rq),
+
+	TP_STRUCT__entry(
+		__field(struct nbd_request *, nbd_request)
+		__field(u64, dev_index)
+		__field(struct request *, request)
+	),
+
+	TP_fast_assign(
+		__entry->nbd_request = NULL;
+		__entry->dev_index = index;
+		__entry->request = rq;
+	),
+
+	TP_printk("nbd%lld: request %p", __entry->dev_index, __entry->request)
+);
+
+#ifdef DEFINE_EVENT_WRITABLE
+#undef NBD_DEFINE_EVENT
+#define NBD_DEFINE_EVENT(template, call, proto, args, size)		\
+	DEFINE_EVENT_WRITABLE(template, call, PARAMS(proto),		\
+			      PARAMS(args), size)
+#else
+#undef NBD_DEFINE_EVENT
+#define NBD_DEFINE_EVENT(template, call, proto, args, size)		\
+	DEFINE_EVENT(template, call, PARAMS(proto), PARAMS(args))
+#endif
+
+NBD_DEFINE_EVENT(nbd_send_request, nbd_send_request,
+
+	TP_PROTO(struct nbd_request *nbd_request, int index,
+		 struct request *rq),
+
+	TP_ARGS(nbd_request, index, rq),
+
+	sizeof(struct nbd_request)
+);
+
+#endif
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>