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, 119 insertions, 0 deletions

diff --git a/include/trace/events/mlxsw.h b/include/trace/events/mlxsw.h
new file mode 100644
index 000000000..19a25ed32
--- /dev/null
+++ b/include/trace/events/mlxsw.h
@@ -0,0 +1,119 @@
+/* SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0 */
+/* Copyright (c) 2019 Mellanox Technologies. All rights reserved */
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM mlxsw
+
+#if !defined(_MLXSW_TRACEPOINT_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _MLXSW_TRACEPOINT_H
+
+#include <linux/tracepoint.h>
+
+struct mlxsw_sp;
+struct mlxsw_sp_acl_atcam_region;
+struct mlxsw_sp_acl_tcam_vregion;
+
+TRACE_EVENT(mlxsw_sp_acl_atcam_entry_add_ctcam_spill,
+	TP_PROTO(const struct mlxsw_sp *mlxsw_sp,
+		 const struct mlxsw_sp_acl_atcam_region *aregion),
+
+	TP_ARGS(mlxsw_sp, aregion),
+
+	TP_STRUCT__entry(
+		__field(const void *, mlxsw_sp)
+		__field(const void *, aregion)
+	),
+
+	TP_fast_assign(
+		__entry->mlxsw_sp = mlxsw_sp;
+		__entry->aregion = aregion;
+	),
+
+	TP_printk("mlxsw_sp %p, aregion %p",
+		  __entry->mlxsw_sp, __entry->aregion)
+);
+
+TRACE_EVENT(mlxsw_sp_acl_tcam_vregion_rehash,
+	TP_PROTO(const struct mlxsw_sp *mlxsw_sp,
+		 const struct mlxsw_sp_acl_tcam_vregion *vregion),
+
+	TP_ARGS(mlxsw_sp, vregion),
+
+	TP_STRUCT__entry(
+		__field(const void *, mlxsw_sp)
+		__field(const void *, vregion)
+	),
+
+	TP_fast_assign(
+		__entry->mlxsw_sp = mlxsw_sp;
+		__entry->vregion = vregion;
+	),
+
+	TP_printk("mlxsw_sp %p, vregion %p",
+		  __entry->mlxsw_sp, __entry->vregion)
+);
+
+TRACE_EVENT(mlxsw_sp_acl_tcam_vregion_migrate,
+	TP_PROTO(const struct mlxsw_sp *mlxsw_sp,
+		 const struct mlxsw_sp_acl_tcam_vregion *vregion),
+
+	TP_ARGS(mlxsw_sp, vregion),
+
+	TP_STRUCT__entry(
+		__field(const void *, mlxsw_sp)
+		__field(const void *, vregion)
+	),
+
+	TP_fast_assign(
+		__entry->mlxsw_sp = mlxsw_sp;
+		__entry->vregion = vregion;
+	),
+
+	TP_printk("mlxsw_sp %p, vregion %p",
+		  __entry->mlxsw_sp, __entry->vregion)
+);
+
+TRACE_EVENT(mlxsw_sp_acl_tcam_vregion_migrate_end,
+	TP_PROTO(const struct mlxsw_sp *mlxsw_sp,
+		 const struct mlxsw_sp_acl_tcam_vregion *vregion),
+
+	TP_ARGS(mlxsw_sp, vregion),
+
+	TP_STRUCT__entry(
+		__field(const void *, mlxsw_sp)
+		__field(const void *, vregion)
+	),
+
+	TP_fast_assign(
+		__entry->mlxsw_sp = mlxsw_sp;
+		__entry->vregion = vregion;
+	),
+
+	TP_printk("mlxsw_sp %p, vregion %p",
+		  __entry->mlxsw_sp, __entry->vregion)
+);
+
+TRACE_EVENT(mlxsw_sp_acl_tcam_vregion_rehash_rollback_failed,
+	TP_PROTO(const struct mlxsw_sp *mlxsw_sp,
+		 const struct mlxsw_sp_acl_tcam_vregion *vregion),
+
+	TP_ARGS(mlxsw_sp, vregion),
+
+	TP_STRUCT__entry(
+		__field(const void *, mlxsw_sp)
+		__field(const void *, vregion)
+	),
+
+	TP_fast_assign(
+		__entry->mlxsw_sp = mlxsw_sp;
+		__entry->vregion = vregion;
+	),
+
+	TP_printk("mlxsw_sp %p, vregion %p",
+		  __entry->mlxsw_sp, __entry->vregion)
+);
+
+#endif /* _MLXSW_TRACEPOINT_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>