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, 71 insertions, 0 deletions

diff --git a/include/trace/events/hwmon.h b/include/trace/events/hwmon.h
new file mode 100644
index 000000000..3865098f2
--- /dev/null
+++ b/include/trace/events/hwmon.h
@@ -0,0 +1,71 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM hwmon
+
+#if !defined(_TRACE_HWMON_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_HWMON_H
+
+#include <linux/tracepoint.h>
+
+DECLARE_EVENT_CLASS(hwmon_attr_class,
+
+	TP_PROTO(int index, const char *attr_name, long long val),
+
+	TP_ARGS(index, attr_name, val),
+
+	TP_STRUCT__entry(
+		__field(int, index)
+		__string(attr_name, attr_name)
+		__field(long long, val)
+	),
+
+	TP_fast_assign(
+		__entry->index = index;
+		__assign_str(attr_name);
+		__entry->val = val;
+	),
+
+	TP_printk("index=%d, attr_name=%s, val=%lld",
+		  __entry->index,  __get_str(attr_name), __entry->val)
+);
+
+DEFINE_EVENT(hwmon_attr_class, hwmon_attr_show,
+
+	TP_PROTO(int index, const char *attr_name, long long val),
+
+	TP_ARGS(index, attr_name, val)
+);
+
+DEFINE_EVENT(hwmon_attr_class, hwmon_attr_store,
+
+	TP_PROTO(int index, const char *attr_name, long long val),
+
+	TP_ARGS(index, attr_name, val)
+);
+
+TRACE_EVENT(hwmon_attr_show_string,
+
+	TP_PROTO(int index, const char *attr_name, const char *s),
+
+	TP_ARGS(index, attr_name, s),
+
+	TP_STRUCT__entry(
+		__field(int, index)
+		__string(attr_name, attr_name)
+		__string(label, s)
+	),
+
+	TP_fast_assign(
+		__entry->index = index;
+		__assign_str(attr_name);
+		__assign_str(label);
+	),
+
+	TP_printk("index=%d, attr_name=%s, val=%s",
+		  __entry->index, __get_str(attr_name), __get_str(label))
+);
+
+#endif /* _TRACE_HWMON_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>