cpu/hotplug: Add tracepoints

We want to trace the hotplug machinery. Add tracepoints to track the
invocation of callbacks and their result.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: Rik van Riel <riel@redhat.com>
Cc: Rafael Wysocki <rafael.j.wysocki@intel.com>
Cc: "Srivatsa S. Bhat" <srivatsa@mit.edu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Turner <pjt@google.com>
Link: http://lkml.kernel.org/r/20160226182340.593563875@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

include/trace/events/cpuhp.h

+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM cpuhp
+
+#if !defined(_TRACE_CPUHP_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_CPUHP_H
+
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(cpuhp_enter,
+
+	TP_PROTO(unsigned int cpu,
+		 int target,
+		 int idx,
+		 int (*fun)(unsigned int)),
+
+	TP_ARGS(cpu, target, idx, fun),
+
+	TP_STRUCT__entry(
+		__field( unsigned int,	cpu		)
+		__field( int,		target		)
+		__field( int,		idx		)
+		__field( void *,	fun		)
+	),
+
+	TP_fast_assign(
+		__entry->cpu	= cpu;
+		__entry->target	= target;
+		__entry->idx	= idx;
+		__entry->fun	= fun;
+	),
+
+	TP_printk("cpu: %04u target: %3d step: %3d (%pf)",
+		  __entry->cpu, __entry->target, __entry->idx, __entry->fun)
+);
+
+TRACE_EVENT(cpuhp_exit,
+
+	TP_PROTO(unsigned int cpu,
+		 int state,
+		 int idx,
+		 int ret),
+
+	TP_ARGS(cpu, state, idx, ret),
+
+	TP_STRUCT__entry(
+		__field( unsigned int,	cpu		)
+		__field( int,		state		)
+		__field( int,		idx		)
+		__field( int,		ret		)
+	),
+
+	TP_fast_assign(
+		__entry->cpu	= cpu;
+		__entry->state	= state;
+		__entry->idx	= idx;
+		__entry->ret	= ret;
+	),
+
+	TP_printk(" cpu: %04u  state: %3d step: %3d ret: %d",
+		  __entry->cpu, __entry->state, __entry->idx,  __entry->ret)
+);
+
+#endif
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>