tracing/README: Add event file usage to tracing mini-HOWTO

It would be useful to have a cheat-sheet for everything under
tracing/events/ alongside the existing text describing the other files
in the tracing/ dir.

Add short descriptions of the directories and files under events/
along with examples, similar to the existing text for the other files
in tracing/.

Also clean up a few minor alignment problems noticed when adding the
new text.

Link: http://lkml.kernel.org/r/1389993104.3040.445.camel@empanada

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
tracing: Fix formatting of trace README file

Fix the formatting of the README file in the trace debugfs to fit in
an 80 character window.

Also add a comment about the event trigger counter with regards to
traceon and traceoff.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
tracing: Check if tracing is enabled in trace_puts()

If trace_puts() is used very early in boot up, it can crash the machine
if it is called before the ring buffer is allocated. If a trace_printk()
is used with no arguments, then it will be converted into a trace_puts()
and suffer the same fate.

Cc: stable@vger.kernel.org # 3.10+
Fixes: 09ae72348ecc "tracing: Add trace_puts() for even faster trace_printk() tracing"
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Merge tag 'trace-fixes-3.14' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing fixes from Steven Rostedt:
 "The first two patches fix the debugfs README file to reflect better
  the new features added to 3.14.

  The third patch is a minor bugfix to the trace_puts() functions that
  will crash the system if a developer adds one before the tracing
  system is setup.  It also affects trace_printk() if it has no
  arguments, as the code will convert it to a trace_puts() as well.

  Note, this bug will not affect unmodified kernels, as trace_printk()
  and trace_puts() should only be used by developers for testing"

* tag 'trace-fixes-3.14' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Check if tracing is enabled in trace_puts()
  tracing: Fix formatting of trace README file
  tracing/README: Add event file usage to tracing mini-HOWTO