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, 213 insertions, 0 deletions

diff --git a/include/trace/events/irq.h b/include/trace/events/irq.h
new file mode 100644
index 000000000..837c1740d
--- /dev/null
+++ b/include/trace/events/irq.h
@@ -0,0 +1,213 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM irq
+
+#if !defined(_TRACE_IRQ_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_IRQ_H
+
+#include <linux/tracepoint.h>
+
+struct irqaction;
+struct softirq_action;
+
+#define SOFTIRQ_NAME_LIST				\
+			 softirq_name(HI)		\
+			 softirq_name(TIMER)		\
+			 softirq_name(NET_TX)		\
+			 softirq_name(NET_RX)		\
+			 softirq_name(BLOCK)		\
+			 softirq_name(IRQ_POLL)		\
+			 softirq_name(TASKLET)		\
+			 softirq_name(SCHED)		\
+			 softirq_name(HRTIMER)		\
+			 softirq_name_end(RCU)
+
+#undef softirq_name
+#undef softirq_name_end
+
+#define softirq_name(sirq) TRACE_DEFINE_ENUM(sirq##_SOFTIRQ);
+#define softirq_name_end(sirq)  TRACE_DEFINE_ENUM(sirq##_SOFTIRQ);
+
+SOFTIRQ_NAME_LIST
+
+#undef softirq_name
+#undef softirq_name_end
+
+#define softirq_name(sirq) { sirq##_SOFTIRQ, #sirq },
+#define softirq_name_end(sirq) { sirq##_SOFTIRQ, #sirq }
+
+#define show_softirq_name(val)				\
+	__print_symbolic(val, SOFTIRQ_NAME_LIST)
+
+/**
+ * irq_handler_entry - called immediately before the irq action handler
+ * @irq: irq number
+ * @action: pointer to struct irqaction
+ *
+ * The struct irqaction pointed to by @action contains various
+ * information about the handler, including the device name,
+ * @action->name, and the device id, @action->dev_id. When used in
+ * conjunction with the irq_handler_exit tracepoint, we can figure
+ * out irq handler latencies.
+ */
+TRACE_EVENT(irq_handler_entry,
+
+	TP_PROTO(int irq, struct irqaction *action),
+
+	TP_ARGS(irq, action),
+
+	TP_STRUCT__entry(
+		__field(	int,	irq		)
+		__string(	name,	action->name	)
+	),
+
+	TP_fast_assign(
+		__entry->irq = irq;
+		__assign_str(name);
+	),
+
+	TP_printk("irq=%d name=%s", __entry->irq, __get_str(name))
+);
+
+/**
+ * irq_handler_exit - called immediately after the irq action handler returns
+ * @irq: irq number
+ * @action: pointer to struct irqaction
+ * @ret: return value
+ *
+ * If the @ret value is set to IRQ_HANDLED, then we know that the corresponding
+ * @action->handler successfully handled this irq. Otherwise, the irq might be
+ * a shared irq line, or the irq was not handled successfully. Can be used in
+ * conjunction with the irq_handler_entry to understand irq handler latencies.
+ */
+TRACE_EVENT(irq_handler_exit,
+
+	TP_PROTO(int irq, struct irqaction *action, int ret),
+
+	TP_ARGS(irq, action, ret),
+
+	TP_STRUCT__entry(
+		__field(	int,	irq	)
+		__field(	int,	ret	)
+	),
+
+	TP_fast_assign(
+		__entry->irq	= irq;
+		__entry->ret	= ret;
+	),
+
+	TP_printk("irq=%d ret=%s",
+		  __entry->irq, __entry->ret ? "handled" : "unhandled")
+);
+
+DECLARE_EVENT_CLASS(softirq,
+
+	TP_PROTO(unsigned int vec_nr),
+
+	TP_ARGS(vec_nr),
+
+	TP_STRUCT__entry(
+		__field(	unsigned int,	vec	)
+	),
+
+	TP_fast_assign(
+		__entry->vec = vec_nr;
+	),
+
+	TP_printk("vec=%u [action=%s]", __entry->vec,
+		  show_softirq_name(__entry->vec))
+);
+
+/**
+ * softirq_entry - called immediately before the softirq handler
+ * @vec_nr:  softirq vector number
+ *
+ * When used in combination with the softirq_exit tracepoint
+ * we can determine the softirq handler routine.
+ */
+DEFINE_EVENT(softirq, softirq_entry,
+
+	TP_PROTO(unsigned int vec_nr),
+
+	TP_ARGS(vec_nr)
+);
+
+/**
+ * softirq_exit - called immediately after the softirq handler returns
+ * @vec_nr:  softirq vector number
+ *
+ * When used in combination with the softirq_entry tracepoint
+ * we can determine the softirq handler routine.
+ */
+DEFINE_EVENT(softirq, softirq_exit,
+
+	TP_PROTO(unsigned int vec_nr),
+
+	TP_ARGS(vec_nr)
+);
+
+/**
+ * softirq_raise - called immediately when a softirq is raised
+ * @vec_nr:  softirq vector number
+ *
+ * When used in combination with the softirq_entry tracepoint
+ * we can determine the softirq raise to run latency.
+ */
+DEFINE_EVENT(softirq, softirq_raise,
+
+	TP_PROTO(unsigned int vec_nr),
+
+	TP_ARGS(vec_nr)
+);
+
+DECLARE_EVENT_CLASS(tasklet,
+
+	TP_PROTO(struct tasklet_struct *t, void *func),
+
+	TP_ARGS(t, func),
+
+	TP_STRUCT__entry(
+		__field(	void *,	tasklet)
+		__field(	void *,	func)
+	),
+
+	TP_fast_assign(
+		__entry->tasklet = t;
+		__entry->func = func;
+	),
+
+	TP_printk("tasklet=%ps function=%ps", __entry->tasklet, __entry->func)
+);
+
+/**
+ * tasklet_entry - called immediately before the tasklet is run
+ * @t: tasklet pointer
+ * @func: tasklet callback or function being run
+ *
+ * Used to find individual tasklet execution time
+ */
+DEFINE_EVENT(tasklet, tasklet_entry,
+
+	TP_PROTO(struct tasklet_struct *t, void *func),
+
+	TP_ARGS(t, func)
+);
+
+/**
+ * tasklet_exit - called immediately after the tasklet is run
+ * @t: tasklet pointer
+ * @func: tasklet callback or function being run
+ *
+ * Used to find individual tasklet execution time
+ */
+DEFINE_EVENT(tasklet, tasklet_exit,
+
+	TP_PROTO(struct tasklet_struct *t, void *func),
+
+	TP_ARGS(t, func)
+);
+
+#endif /*  _TRACE_IRQ_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>