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, 140 insertions, 0 deletions

diff --git a/include/trace/events/sunvnet.h b/include/trace/events/sunvnet.h
new file mode 100644
index 000000000..8d444f1bb
--- /dev/null
+++ b/include/trace/events/sunvnet.h
@@ -0,0 +1,140 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM sunvnet
+
+#if !defined(_TRACE_SUNVNET_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_SUNVNET_H
+
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(vnet_rx_one,
+
+	TP_PROTO(int lsid, int rsid, int index, int needs_ack),
+
+	TP_ARGS(lsid, rsid, index, needs_ack),
+
+	TP_STRUCT__entry(
+		__field(int, lsid)
+		__field(int, rsid)
+		__field(int, index)
+		__field(int, needs_ack)
+	),
+
+	TP_fast_assign(
+		__entry->lsid = lsid;
+		__entry->rsid = rsid;
+		__entry->index = index;
+		__entry->needs_ack = needs_ack;
+	),
+
+	TP_printk("(%x:%x) walk_rx_one index %d; needs_ack %d",
+		__entry->lsid, __entry->rsid,
+		__entry->index, __entry->needs_ack)
+);
+
+DECLARE_EVENT_CLASS(vnet_tx_stopped_ack_template,
+
+	TP_PROTO(int lsid, int rsid, int ack_end, int npkts),
+
+	TP_ARGS(lsid, rsid, ack_end, npkts),
+
+	TP_STRUCT__entry(
+		__field(int, lsid)
+		__field(int, rsid)
+		__field(int, ack_end)
+		__field(int, npkts)
+	),
+
+	TP_fast_assign(
+		__entry->lsid = lsid;
+		__entry->rsid = rsid;
+		__entry->ack_end = ack_end;
+		__entry->npkts = npkts;
+	),
+
+	TP_printk("(%x:%x) stopped ack for %d; npkts %d",
+		__entry->lsid, __entry->rsid,
+		__entry->ack_end, __entry->npkts)
+);
+DEFINE_EVENT(vnet_tx_stopped_ack_template, vnet_tx_send_stopped_ack,
+	     TP_PROTO(int lsid, int rsid, int ack_end, int npkts),
+	     TP_ARGS(lsid, rsid, ack_end, npkts));
+DEFINE_EVENT(vnet_tx_stopped_ack_template, vnet_tx_defer_stopped_ack,
+	     TP_PROTO(int lsid, int rsid, int ack_end, int npkts),
+	     TP_ARGS(lsid, rsid, ack_end, npkts));
+DEFINE_EVENT(vnet_tx_stopped_ack_template, vnet_tx_pending_stopped_ack,
+	     TP_PROTO(int lsid, int rsid, int ack_end, int npkts),
+	     TP_ARGS(lsid, rsid, ack_end, npkts));
+
+TRACE_EVENT(vnet_rx_stopped_ack,
+
+	TP_PROTO(int lsid, int rsid, int end),
+
+	TP_ARGS(lsid, rsid, end),
+
+	TP_STRUCT__entry(
+		__field(int, lsid)
+		__field(int, rsid)
+		__field(int, end)
+	),
+
+	TP_fast_assign(
+		__entry->lsid = lsid;
+		__entry->rsid = rsid;
+		__entry->end = end;
+	),
+
+	TP_printk("(%x:%x) stopped ack for index %d",
+		__entry->lsid, __entry->rsid, __entry->end)
+);
+
+TRACE_EVENT(vnet_tx_trigger,
+
+	TP_PROTO(int lsid, int rsid, int start, int err),
+
+	TP_ARGS(lsid, rsid, start, err),
+
+	TP_STRUCT__entry(
+		__field(int, lsid)
+		__field(int, rsid)
+		__field(int, start)
+		__field(int, err)
+	),
+
+	TP_fast_assign(
+		__entry->lsid = lsid;
+		__entry->rsid = rsid;
+		__entry->start = start;
+		__entry->err = err;
+	),
+
+	TP_printk("(%x:%x) Tx trigger for %d sent with err %d %s",
+		__entry->lsid, __entry->rsid, __entry->start,
+		__entry->err, __entry->err > 0 ? "(ok)" : " ")
+);
+
+TRACE_EVENT(vnet_skip_tx_trigger,
+
+	TP_PROTO(int lsid, int rsid, int last),
+
+	TP_ARGS(lsid, rsid, last),
+
+	TP_STRUCT__entry(
+		__field(int, lsid)
+		__field(int, rsid)
+		__field(int, last)
+	),
+
+	TP_fast_assign(
+		__entry->lsid = lsid;
+		__entry->rsid = rsid;
+		__entry->last = last;
+	),
+
+	TP_printk("(%x:%x) Skip Tx trigger. Last trigger sent was %d",
+		__entry->lsid, __entry->rsid, __entry->last)
+);
+#endif /* _TRACE_SOCK_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>