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, 149 insertions, 0 deletions

diff --git a/include/trace/events/rpm.h b/include/trace/events/rpm.h
new file mode 100644
index 000000000..2b0b4b6ef
--- /dev/null
+++ b/include/trace/events/rpm.h
@@ -0,0 +1,149 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM rpm
+
+#if !defined(_TRACE_RUNTIME_POWER_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_RUNTIME_POWER_H
+
+#include <linux/ktime.h>
+#include <linux/tracepoint.h>
+
+struct device;
+
+/*
+ * The rpm_internal events are used for tracing some important
+ * runtime pm internal functions.
+ */
+DECLARE_EVENT_CLASS(rpm_internal,
+
+	TP_PROTO(struct device *dev, int flags),
+
+	TP_ARGS(dev, flags),
+
+	TP_STRUCT__entry(
+		__string(       name,		dev_name(dev)	)
+		__field(        int,            flags           )
+		__field(        int ,   	usage_count	)
+		__field(        int ,   	disable_depth   )
+		__field(        int ,   	runtime_auto	)
+		__field(        int ,   	request_pending	)
+		__field(        int ,   	irq_safe	)
+		__field(        int ,   	child_count 	)
+	),
+
+	TP_fast_assign(
+		__assign_str(name);
+		__entry->flags = flags;
+		__entry->usage_count = atomic_read(
+			&dev->power.usage_count);
+		__entry->disable_depth = dev->power.disable_depth;
+		__entry->runtime_auto = dev->power.runtime_auto;
+		__entry->request_pending = dev->power.request_pending;
+		__entry->irq_safe = dev->power.irq_safe;
+		__entry->child_count = atomic_read(
+			&dev->power.child_count);
+	),
+
+	TP_printk("%s flags-%x cnt-%-2d dep-%-2d auto-%-1d p-%-1d"
+			" irq-%-1d child-%d",
+			__get_str(name), __entry->flags,
+			__entry->usage_count,
+			__entry->disable_depth,
+			__entry->runtime_auto,
+			__entry->request_pending,
+			__entry->irq_safe,
+			__entry->child_count
+		 )
+);
+DEFINE_EVENT(rpm_internal, rpm_suspend,
+
+	TP_PROTO(struct device *dev, int flags),
+
+	TP_ARGS(dev, flags)
+);
+DEFINE_EVENT(rpm_internal, rpm_resume,
+
+	TP_PROTO(struct device *dev, int flags),
+
+	TP_ARGS(dev, flags)
+);
+DEFINE_EVENT(rpm_internal, rpm_idle,
+
+	TP_PROTO(struct device *dev, int flags),
+
+	TP_ARGS(dev, flags)
+);
+DEFINE_EVENT(rpm_internal, rpm_usage,
+
+	TP_PROTO(struct device *dev, int flags),
+
+	TP_ARGS(dev, flags)
+);
+
+TRACE_EVENT(rpm_return_int,
+	TP_PROTO(struct device *dev, unsigned long ip, int ret),
+	TP_ARGS(dev, ip, ret),
+
+	TP_STRUCT__entry(
+		__string(       name,		dev_name(dev))
+		__field(	unsigned long,		ip	)
+		__field(	int,			ret	)
+	),
+
+	TP_fast_assign(
+		__assign_str(name);
+		__entry->ip = ip;
+		__entry->ret = ret;
+	),
+
+	TP_printk("%pS:%s ret=%d", (void *)__entry->ip, __get_str(name),
+		__entry->ret)
+);
+
+#define RPM_STATUS_STRINGS \
+	EM(RPM_INVALID, "RPM_INVALID") \
+	EM(RPM_ACTIVE, "RPM_ACTIVE") \
+	EM(RPM_RESUMING, "RPM_RESUMING") \
+	EM(RPM_SUSPENDED, "RPM_SUSPENDED") \
+	EMe(RPM_SUSPENDING, "RPM_SUSPENDING")
+
+/* Enums require being exported to userspace, for user tool parsing. */
+#undef EM
+#undef EMe
+#define EM(a, b)	TRACE_DEFINE_ENUM(a);
+#define EMe(a, b)	TRACE_DEFINE_ENUM(a);
+
+RPM_STATUS_STRINGS
+
+/*
+ * Now redefine the EM() and EMe() macros to map the enums to the strings that
+ * will be printed in the output.
+ */
+#undef EM
+#undef EMe
+#define EM(a, b)	{ a, b },
+#define EMe(a, b)	{ a, b }
+
+TRACE_EVENT(rpm_status,
+	TP_PROTO(struct device *dev, enum rpm_status status),
+	TP_ARGS(dev, status),
+
+	TP_STRUCT__entry(
+		__string(name,	dev_name(dev))
+		__field(int,	status)
+	),
+
+	TP_fast_assign(
+		__assign_str(name);
+		__entry->status = status;
+	),
+
+	TP_printk("%s status=%s", __get_str(name),
+		__print_symbolic(__entry->status, RPM_STATUS_STRINGS))
+);
+
+#endif /* _TRACE_RUNTIME_POWER_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>