tracing: Fix events.rst section numbering

  See Documentation/trace/histogram.rst for details and examples.

6.3 In-kernel trace event API

-----------------------------

7. In-kernel trace event API

============================

In most cases, the command-line interface to trace events is more than

sufficient.  Sometimes, however, applications might find the need for

  - tracing synthetic events from in-kernel code

  - the low-level "dynevent_cmd" API

6.3.1 Dyamically creating synthetic event definitions

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7.1 Dyamically creating synthetic event definitions

---------------------------------------------------

There are a couple ways to create a new synthetic event from a kernel

module or other kernel code.

At this point, the event object is ready to be used for tracing new

events.

6.3.3 Tracing synthetic events from in-kernel code

--------------------------------------------------

7.2 Tracing synthetic events from in-kernel code

------------------------------------------------

To trace a synthetic event, there are several options.  The first

option is to trace the event in one call, using synth_event_trace()

synth_event_add_next_val() or synth_event_add_val() to add the values

piecewise.

6.3.3.1 Tracing a synthetic event all at once

---------------------------------------------

7.2.1 Tracing a synthetic event all at once

-------------------------------------------

To trace a synthetic event all at once, the synth_event_trace() or

synth_event_trace_array() functions can be used.

       ret = synth_event_delete("schedtest");

6.3.3.1 Tracing a synthetic event piecewise

-------------------------------------------

7.2.2 Tracing a synthetic event piecewise

-----------------------------------------

To trace a synthetic using the piecewise method described above, the

synth_event_trace_start() function is used to 'open' the synthetic

of whether any of the add calls failed (say due to a bad field name

being passed in).

6.3.4 Dyamically creating kprobe and kretprobe event definitions

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7.3 Dyamically creating kprobe and kretprobe event definitions

--------------------------------------------------------------

To create a kprobe or kretprobe trace event from kernel code, the

kprobe_event_gen_cmd_start() or kretprobe_event_gen_cmd_start()

  ret = kprobe_event_delete("gen_kprobe_test");

6.3.4 The "dynevent_cmd" low-level API

--------------------------------------

7.4 The "dynevent_cmd" low-level API

------------------------------------

Both the in-kernel synthetic event and kprobe interfaces are built on

top of a lower-level "dynevent_cmd" interface.  This interface is