Add a new ftrace test that creates three threads. One that creates and
removes an ftrace instance, one that reads the instance, and one that enables
and disables events in the instance. This is a stress test for accessing and
removing instances at the same time.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Filtering of events requires the data to be written to the ring buffer
before it can be decided to filter or not. This is because the parameters of
the filter are based on the result that is written to the ring buffer and
not on the parameters that are passed into the trace functions.

The ftrace ring buffer is optimized for writing into the ring buffer and
committing. The discard procedure used when filtering decides the event
should be discarded is much more heavy weight. Thus, using a temporary
filter when filtering events can speed things up drastically.

Without a temp buffer we have:

 # trace-cmd start -p nop
 # perf stat -r 10 hackbench 50
       0.790706626 seconds time elapsed ( +-  0.71% )

 # trace-cmd start -e all
 # perf stat -r 10 hackbench 50
       1.566904059 seconds time elapsed ( +-  0.27% )

 # trace-cmd start -e all -f 'common_preempt_count==20'
 # perf stat -r 10 hackbench 50
       1.690598511 seconds time elapsed ( +-  0.19% )

 # trace-cmd start -e all -f 'common_preempt_count!=20'
 # perf stat -r 10 hackbench 50
       1.707486364 seconds time elapsed ( +-  0.30% )

The first run above is without any tracing, just to get a based figure.
hackbench takes ~0.79 seconds to run on the system.

The second run enables tracing all events where nothing is filtered. This
increases the time by 100% and hackbench takes 1.57 seconds to run.

The third run filters all events where the preempt count will equal "20"
(this should never happen) thus all events are discarded. This takes 1.69
seconds to run. This is 10% slower than just committing the events!

The last run enables all events and filters where the filter will commit all
events, and this takes 1.70 seconds to run. The filtering overhead is
approximately 10%. Thus, the discard and commit of an event from the ring
buffer may be about the same time.

With this patch, the numbers change:

 # trace-cmd start -p nop
 # perf stat -r 10 hackbench 50
       0.778233033 seconds time elapsed ( +-  0.38% )

 # trace-cmd start -e all
 # perf stat -r 10 hackbench 50
       1.582102692 seconds time elapsed ( +-  0.28% )

 # trace-cmd start -e all -f 'common_preempt_count==20'
 # perf stat -r 10 hackbench 50
       1.309230710 seconds time elapsed ( +-  0.22% )

 # trace-cmd start -e all -f 'common_preempt_count!=20'
 # perf stat -r 10 hackbench 50
       1.786001924 seconds time elapsed ( +-  0.20% )

The first run is again the base with no tracing.

The second run is all tracing with no filtering. It is a little slower, but
that may be well within the noise.

The third run shows that discarding all events only took 1.3 seconds. This
is a speed up of 23%! The discard is much faster than even the commit.

The one downside is shown in the last run. Events that are not discarded by
the filter will take longer to add, this is due to the extra copy of the
event.

Cc: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Nothing sets TRACE_EVENT_FL_USE_CALL_FILTER anymore. Remove it.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

trace_current_buffer_lock_reserve() has no more users. Remove it.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

The only user of trace_current_buffer_lock_reserve() is in the boot up self
tests. Restructure the code a little to have that code use what everything
else uses: trace_event_buffer_lock_reserve().
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

There's no real difference between trace_buffer_unlock_commit() and
trace_buffer_unlock_commit_regs() except that the former passes NULL to
ftrace_stack_trace() instead of regs. Have the former be a static inline of
the latter which passes NULL for regs.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

The function trace_current_buffer_discard_commit() has no callers, remove
it.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

The functions trace_buffer_unlock_commit() and the _regs() version are only
used within the kernel/trace directory. Move them to the local header and
remove the export as well.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

The function filter_check_discard() is small and only called by one user,
its code can be folded into that one caller and make the code a bit less
comlplex.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Nothing outside of the tracing directory calls filter_check_discard() or
check_filter_check_discard(). They should not be called by modules. Move
their prototypes into the local tracing header and remove their
EXPORT_SYMBOL() macros.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

The functions event_trigger_unlock_commit() and
event_trigger_unlock_commit_regs() are no longer used outside the tracing
system. Move them out of the generic headers and into the local one.

Along with __event_trigger_test_discard() that is only used by them.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

With the following code snippet:

    ...
    char buf[64];
    ...
    if (copy_from_user(&buf, ubuf, cnt))
    ...

Even though the value of "&buf" equals "buf", but there is no need
to get the address of the "buf" again. Use "buf" instead of "&buf".

Link: http://lkml.kernel.org/r/20160418152329.18b72bea@debianSigned-off-by: Wang Xiaoqiang <wangxq10@lzu.edu.cn>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

If tracing_map_elt_alloc() fails, it will return ERR_PTR() instead of
NULL, so change the check to IS_ERROR().  We also need to set the
failed entry in the map->elts array to NULL instead of ERR_PTR() so
tracing_map_free_elts() doesn't try freeing an ERR_PTR().

tracing_map_free_elts() should also zero out what it frees so a
reentrant call won't find previously freed elements.

Link: http://lkml.kernel.org/r/f29d03b00bce3aac8cf151a8a30e6c83e5fee66d.1461610073.git.tom.zanussi@linux.intel.comSigned-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Smatch flagged create_hist_field() as possibly being able to
dereference a NULL pointer, although the current code exits in all
cases where the event field could be NULL, so it's not actually a
problem.

Still, to prevent future changes to the code from overlooking new
cases, make the NULL pointer check explicit and warn once in that
case.

Link: http://lkml.kernel.org/r/cfbc003f534a3e441b4313272fd412310aba6336.1461610073.git.tom.zanussi@linux.intel.comSigned-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

tracing_map_elt_alloc() returns ERR_PTRs on error, never NULL.

Fixes: 08d43a5f ('tracing: Add lock-free tracing_map')
Link: http://lkml.kernel.org/r/20160423102347.GA11136@mwandaAcked-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

As the event-fork option requires doing work when enabled and disabled, it
can not be passed down to created instances. The instance must clear this
flag when it is created, and must clear it when its removed.

As more options may be created with this need, a macro ZEROED_TRACE_FLAGS is
created that holds the flags that must not be inherited by the top level
instance, and must be cleared on removal of instances.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Fengguang Wu's bot found two comparisons of unsigned integers to zero. These
were real bugs, as it would miss error conditions returned to zero.

trace_events_hist.c:426:6-9: WARNING: Unsigned expression compared with zero: idx < 0
trace_events_hist.c:568:5-14: WARNING: Unsigned expression compared with zero: n_entries < 0
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Add a test for log2 modifier of hist trigger in hist_mod.tc.
Here is the test result.

  ----
  # ./ftracetest test.d/trigger/trigger-hist-mod.tc
  === Ftrace unit tests ===
  [1] event trigger - test histogram modifiers	[PASS]

  # of passed:  1
  # of failed:  0
  # of unresolved:  0
  # of untested:  0
  # of unsupported:  0
  # of xfailed:  0
  # of undefined(test bug):  0
  ----

Link: http://lkml.kernel.org/r/3f1ab735c06a50b1b40d3e96b8b6a3e5ea62fd86.1457029949.git.tom.zanussi@linux.intel.comSigned-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Allow users to have numeric fields displayed as log2 values in case
value range is very wide by appending '.log2' to field names.

For example,

  # echo 'hist:key=bytes_req' > kmalloc/trigger
  # cat kmalloc/hist

  { bytes_req:        504 } hitcount:          1
  { bytes_req:         11 } hitcount:          1
  { bytes_req:        104 } hitcount:          1
  { bytes_req:         48 } hitcount:          1
  { bytes_req:       2048 } hitcount:          1
  { bytes_req:       4096 } hitcount:          1
  { bytes_req:        240 } hitcount:          1
  { bytes_req:        392 } hitcount:          1
  { bytes_req:         13 } hitcount:          1
  { bytes_req:         28 } hitcount:          1
  { bytes_req:         12 } hitcount:          1
  { bytes_req:         64 } hitcount:          2
  { bytes_req:        128 } hitcount:          2
  { bytes_req:         32 } hitcount:          2
  { bytes_req:          8 } hitcount:         11
  { bytes_req:         10 } hitcount:         13
  { bytes_req:         24 } hitcount:         25
  { bytes_req:        160 } hitcount:         29
  { bytes_req:         16 } hitcount:         33
  { bytes_req:         80 } hitcount:         36

When using '.log2' modifier, the output looks like:

  # echo 'hist:key=bytes_req.log2' > kmalloc/trigger
  # cat kmalloc/hist

  { bytes_req: ~ 2^12 } hitcount:          1
  { bytes_req: ~ 2^11 } hitcount:          1
  { bytes_req: ~ 2^9  } hitcount:          2
  { bytes_req: ~ 2^6  } hitcount:          3
  { bytes_req: ~ 2^3  } hitcount:         13
  { bytes_req: ~ 2^5  } hitcount:         19
  { bytes_req: ~ 2^8  } hitcount:         49
  { bytes_req: ~ 2^7  } hitcount:         57
  { bytes_req: ~ 2^4  } hitcount:         74

Link: http://lkml.kernel.org/r/7ff396b246c6a881f46b979735fddf05a0d6c71a.1457029949.git.tom.zanussi@linux.intel.com

Cc: Tom Zanussi <tom.zanussi@linux.intel.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Add the hist trigger testcases for ftracetest.
This checks the basic histogram trigger behaviors like as;
 - Histogram trigger itself
 - Histogram with string key
 - Histogram with compound keys
 - Histogram with sort key
 - Histogram trigger modifiers (execname, hex, syscall)
 - Multiple histograms on an event
 - Named histogram
 - Named histogram on multi events

Here is the test result.
  ----
  # ./ftracetest test.d/trigger/*hist*.tc
  === Ftrace unit tests ===
  [1] event trigger - test histogram modifiers    [PASS]
  [2] event trigger - test histogram trigger      [PASS]
  [3] event trigger - test multiple histogram triggers    [PASS]

  # of passed:  3
  # of failed:  0
  # of unresolved:  0
  # of untested:  0
  # of unsupported:  0
  # of xfailed:  0
  # of undefined(test bug):  0
  ----

Link: http://lkml.kernel.org/r/17cb3a3d9eeadc3282645147905455a298e7fbeb.1457029949.git.tom.zanussi@linux.intel.comSigned-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
[Tom Zanussi: Change multihist test from truncate ('>') to append ('>>')]
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

This adds simple event trigger testcases for ftracetest,
which covers following triggers.
 - traceon-traceoff trigger
 - enable/disable_event trigger
 - snapshot trigger
 - stacktrace trigger
 - trigger filters

Here is the test result.

  ----
  # ./ftracetest test.d/trigger/
  === Ftrace unit tests ===
  [1] event trigger - test event enable/disable trigger   [PASS]
  [2] event trigger - test trigger filter [PASS]
  [3] event trigger - test snapshot-trigger       [PASS]
  [4] event trigger - test stacktrace-trigger     [PASS]
  [5] event trigger - test traceon/off trigger    [PASS]

  # of passed:  5
  # of failed:  0
  # of unresolved:  0
  # of untested:  0
  # of unsupported:  0
  # of xfailed:  0
  # of undefined(test bug):  0
  ----

Link: http://lkml.kernel.org/r/12b9c2b289a0dc1e4386e7b77674611a83abca85.1457029949.git.tom.zanussi@linux.intel.comSigned-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Tom Zanussi <tom.zanussi@linux.intel.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Allow users to define 'named' hist triggers.  All triggers created
with the same 'name=xxx' option will update the same shared histogram
data.

This expands the hist trigger syntax from this:

    # echo hist:keys=xxx ... [ if filter] > event/trigger

to this:

    # echo hist:name=xxx:keys=xxx ... [ if filter] > event/trigger

Named histograms must use a 'compatible' set of keys and values, which
means each event added to a set of named triggers must have the same
names and types.

Reading the 'hist' file of any of the participating events will
produce the same output as any other participating event, which is to
be expected since they share the same data.

Link: http://lkml.kernel.org/r/1dbc84ee3322a75daaf5b3ef1d0cc0a2fb682fc7.1457029949.git.tom.zanussi@linux.intel.comSigned-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Named triggers are sets of triggers that share a common set of trigger
data.  An example of functionality that could benefit from this type
of capability would be a set of inlined probes that would each
contribute event counts, for example, to a shared counter data
structure.

The first named trigger registered with a given name owns the common
trigger data that the others subsequently registered with the same
name will reference.  The functions defined here allow users to add,
delete, and find named triggers.

It also adds functions to pause and unpause named triggers; since
named triggers act upon common data, they should also be paused and
unpaused as a group.

Link: http://lkml.kernel.org/r/c09ff648360f65b10a3e321eddafe18060b4a04f.1457029949.git.tom.zanussi@linux.intel.comSigned-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Allow users to define any number of hist triggers per trace event.
Any number of hist triggers may be added for a given event, which may
differ by key, value, or filter.

Reading the event's 'hist' file will display the output of all the
hist triggers defined on an event concatenated in the order they were
defined.

Link: http://lkml.kernel.org/r/48a0c8dd34c344571de880fb35e211c6d9a28961.1457029949.git.tom.zanussi@linux.intel.comSigned-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Add documentation and usage examples for 'hist' triggers.

Link: http://lkml.kernel.org/r/2e13f35f47fea6d647f0efefccfc9673ea84b29f.1457029949.git.tom.zanussi@linux.intel.comSigned-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Similar to enable_event/disable_event triggers, these triggers enable
and disable the aggregation of events into maps rather than enabling
and disabling their writing into the trace buffer.

They can be used to automatically start and stop hist triggers based
on a matching filter condition.

If there's a paused hist trigger on system:event, the following would
start it when the filter condition was hit:

  # echo enable_hist:system:event [ if filter] > event/trigger

And the following would disable a running system:event hist trigger:

  # echo disable_hist:system:event [ if filter] > event/trigger

See Documentation/trace/events.txt for real examples.

Link: http://lkml.kernel.org/r/f812f086e52c8b7c8ad5443487375e03c96a601f.1457029949.git.tom.zanussi@linux.intel.comSigned-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

If we assume the maximum size for a string field, we don't have to
worry about its position.  Since we only allow two keys in a compound
key and having more than one string key in a given compound key
doesn't make much sense anyway, trading a bit of extra space instead
of introducing an arbitrary restriction makes more sense.

We also need to use the event field size for static strings when
copying the contents, otherwise we get random garbage in the key.

Also, cast string return values to avoid warnings on 32-bit compiles.

Finally, rearrange the code without changing any functionality by
moving the compound key updating code into a separate function.

Link: http://lkml.kernel.org/r/8976e1ab04b66bc2700ad1ed0768a2de85ac1983.1457029949.git.tom.zanussi@linux.intel.comSigned-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

The string in a trace event is usually recorded as dynamic array which
is variable length.  But current hist code only support fixed length
array so it cannot support most strings.

This patch fixes it by checking filter_type of the field and get
proper pointer with it.  With this, it can get a histogram of exec()
based on filenames like below:

  # cd /sys/kernel/tracing/events/sched/sched_process_exec
  # cat 'hist:key=filename' > trigger
  # ps
   PID TTY       TIME CMD
     1 ?     00:00:00 init
    29 ?     00:00:00 sh
    38 ?     00:00:00 ps
  # ls
  enable  filter  format  hist  id  trigger
  # cat hist
  # trigger info: hist:keys=filename:vals=hitcount:sort=hitcount:size=2048 [active]

  { filename: /usr/bin/ps                         } hitcount:          1
  { filename: /usr/bin/ls                         } hitcount:          1
  { filename: /usr/bin/cat                        } hitcount:          1

  Totals:
      Hits: 3
      Entries: 3
      Dropped: 0

Link: http://lkml.kernel.org/r/610180d6df0cfdf11ee205452f3b241dea657233.1457029949.git.tom.zanussi@linux.intel.com

Cc: Tom Zanussi <tom.zanussi@linux.intel.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
[ Added (unsigned long) typecast to fix compile warning ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

It's often useful to be able to use a stacktrace as a hash key, for
keeping a count of the number of times a particular call path resulted
in a trace event, for instance.  Add a special key named 'stacktrace'
which can be used as key in a 'keys=' param for this purpose:

    # echo hist:keys=stacktrace ... \
               [ if filter] > event/trigger

Link: http://lkml.kernel.org/r/87515e90b3785232a874a12156174635a348edb1.1457029949.git.tom.zanussi@linux.intel.comSigned-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Allow users to have syscall id fields displayed as syscall names in
the output by appending '.syscall' to field names:

   # echo hist:keys=aaa.syscall ... \
              [ if filter] > event/trigger

Link: http://lkml.kernel.org/r/2bab1e59933d76a14b545bd2e02f80b8b08ac4d3.1457029949.git.tom.zanussi@linux.intel.comSigned-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Allow users to have common_pid field values displayed as program names
in the output by appending '.execname' to a common_pid field name:

   # echo hist:keys=common_pid.execname ... \
              [ if filter] > event/trigger

Link: http://lkml.kernel.org/r/e172e81f10f5b8d1f08450e3763c850f39fbf698.1457029949.git.tom.zanussi@linux.intel.comSigned-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Allow users to have address fields displayed as symbols in the output
by appending '.sym' or 'sym-offset' to field names:

   # echo hist:keys=aaa.sym,bbb.sym-offset ... \
              [ if filter] > event/trigger

Link: http://lkml.kernel.org/r/87d4935821491c0275513f0fbfb9bab8d3d3f079.1457029949.git.tom.zanussi@linux.intel.comSigned-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Allow users to have numeric fields displayed as hex values in the
output by appending '.hex' to field names:

   # echo hist:keys=aaa,bbb.hex:vals=ccc.hex ... \
              [ if filter] > event/trigger

Link: http://lkml.kernel.org/r/67bd431edda2af5798d7694818f7e8d71b6b3463.1457029949.git.tom.zanussi@linux.intel.comSigned-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Allow users to append 'clear' to an existing trigger in order to have
the hash table cleared.

This expands the hist trigger syntax from this:
    # echo hist:keys=xxx:vals=yyy:sort=zzz.descending:pause/cont \
           [ if filter] >> event/trigger

to this:

    # echo hist:keys=xxx:vals=yyy:sort=zzz.descending:pause/cont/clear \
          [ if filter] >> event/trigger

Link: http://lkml.kernel.org/r/ae15dd0d9b2f7af07a37c1ff682063e2dbcdf160.1457029949.git.tom.zanussi@linux.intel.comSigned-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Allow users to append 'pause' or 'continue' to an existing trigger in
order to have it paused or to have a paused trace continue.

This expands the hist trigger syntax from this:
    # echo hist:keys=xxx:vals=yyy:sort=zzz.descending \
          [ if filter] >> event/trigger

to this:

    # echo hist:keys=xxx:vals=yyy:sort=zzz.descending:pause or cont \
          [ if filter] >> event/trigger

Link: http://lkml.kernel.org/r/b672a92c14702cb924cdf6fc27ea1809bed04907.1457029949.git.tom.zanussi@linux.intel.comSigned-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Allow users to specify keys and/or values to sort on.  With this
addition, keys and values specified using the 'keys=' and 'vals='
keywords can be used to sort the hist trigger output via a new 'sort='
keyword.  If multiple sort keys are specified, the output will be
sorted using the second key as a secondary sort key, etc.  The default
sort order is ascending; if the user wants a different sort order,
'.descending' can be appended to the specific sort key.  Before this
addition, output was always sorted by 'hitcount' in ascending order.

This expands the hist trigger syntax from this:

    # echo hist:keys=xxx:vals=yyy \
          [ if filter] > event/trigger

to this:

    # echo hist:keys=xxx:vals=yyy:sort=zzz.descending \
          [ if filter] > event/trigger

Link: http://lkml.kernel.org/r/b30a41db66ba486979c4f987aff5fab500ea53b3.1457029949.git.tom.zanussi@linux.intel.comSigned-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Allow users to specify multiple trace event fields to use in keys by
allowing multiple fields in the 'keys=' keyword.  With this addition,
any unique combination of any of the fields named in the 'keys'
keyword will result in a new entry being added to the hash table.

Link: http://lkml.kernel.org/r/0cfa24e6ac3b0dcece7737d94aa1f322ae3afc4b.1457029949.git.tom.zanussi@linux.intel.comSigned-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Allow users to specify trace event fields to use in aggregated sums
via a new 'vals=' keyword.  Before this addition, the only aggregated
sum supported was the implied value 'hitcount'.  With this addition,
'hitcount' is also supported as an explicit value field, as is any
numeric trace event field.

This expands the hist trigger syntax from this:

  # echo hist:keys=xxx [ if filter] > event/trigger

to this:

  # echo hist:keys=xxx:vals=yyy [ if filter] > event/trigger

Link: http://lkml.kernel.org/r/2a5d1adb5ba6c65d7bb2148e379f2fed47f29a68.1457029949.git.tom.zanussi@linux.intel.comSigned-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

'hist' triggers allow users to continually aggregate trace events,
which can then be viewed afterwards by simply reading a 'hist' file
containing the aggregation in a human-readable format.

The basic idea is very simple and boils down to a mechanism whereby
trace events, rather than being exhaustively dumped in raw form and
viewed directly, are automatically 'compressed' into meaningful tables
completely defined by the user.

This is done strictly via single-line command-line commands and
without the aid of any kind of programming language or interpreter.

A surprising number of typical use cases can be accomplished by users
via this simple mechanism.  In fact, a large number of the tasks that
users typically do using the more complicated script-based tracing
tools, at least during the initial stages of an investigation, can be
accomplished by simply specifying a set of keys and values to be used
in the creation of a hash table.

The Linux kernel trace event subsystem happens to provide an extensive
list of keys and values ready-made for such a purpose in the form of
the event format files associated with each trace event.  By simply
consulting the format file for field names of interest and by plugging
them into the hist trigger command, users can create an endless number
of useful aggregations to help with investigating various properties
of the system.  See Documentation/trace/events.txt for examples.

hist triggers are implemented on top of the existing event trigger
infrastructure, and as such are consistent with the existing triggers
from a user's perspective as well.

The basic syntax follows the existing trigger syntax.  Users start an
aggregation by writing a 'hist' trigger to the event of interest's
trigger file:

  # echo hist:keys=xxx [ if filter] > event/trigger

Once a hist trigger has been set up, by default it continually
aggregates every matching event into a hash table using the event key
and a value field named 'hitcount'.

To view the aggregation at any point in time, simply read the 'hist'
file in the same directory as the 'trigger' file:

  # cat event/hist

The detailed syntax provides additional options for user control, and
is described exhaustively in Documentation/trace/events.txt and in the
virtual tracing/README file in the tracing subsystem.

Link: http://lkml.kernel.org/r/72d263b5e1853fe9c314953b65833c3aa75479f2.1457029949.git.tom.zanussi@linux.intel.comSigned-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Make it clear exactly how many keys and values are supported through
better defines, and add 1 to the vals count, since normally clients
want support for at least a hitcount and two other values.

Also, note the error return value for tracing_map_add_key/val_field()
in the comments.

Link: http://lkml.kernel.org/r/6696fa02ebc716aa344c27a571a2afaa25e5b4d4.1457029949.git.tom.zanussi@linux.intel.comSigned-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>