[PATCH v5 0/8] tracing: Hist trigger snapshot and onchange additions

[Tom Zanussi]

From: Tom Zanussi <tom.zanussi@xxxxxxxxxxxxxxx>

Hi,

This is v5 of the hist trigger snapshot and onchange additions
patchset.  It's the same as v4, but adds a test case for the new trace
syntax as suggested by Masami, and also adds a new test case for the
onchange addition.

v4->v5 changes:

  - added 'trace' keyword test case
  - added 'onchange' handler test case

v3->v4 changes:

  - added 'trace' keyword for generating synthetic events
  - fix elt_data leak
  - changed cond_update to cond_update_fn_t

v2->v3 changes:

  - fixed problem where trace actions were only being allowed for
    onmatch handlers - now trace actions can be used with any handler.
  - fixed problem where no action was being assigned to onmatch
    handlers if save or snapshot actions were specified.

v1->v2 changes:

  - added missing tracing_cond_snapshot_data() definition for when
    CONFIG_TRACER_SNAPSHOT not defined
  - removed an unnecessary WARN_ON() in track_data_snapshot_print()


Original text:

This patchset adds some useful new functions to the hist
trigger code: a snapshot action and an onchange handler.

In order to make it easier to add these and in the process make the
code more generic, I separated the code into explicit 'handlers' and
'actions', handlers being things like 'onmax' and 'onchange', and
'actions' being things like 'take a snapshot' or 'save some fields'.

The first few patches do that basic refactoring, which make it easier
to add the subsequent changes that arbitrarily combine actions and
handlers.

The fourth patch adds a 'conditional snapshot' capability that via a
new tracing_snaphot_cond() function extends the existing snapshot
code.  It allows the caller to associate some user data with the
snapshot that can be checked and saved in an update() callback whose
return value determines whether the snapshot should be taken or not.

The remaining patches finally add the new snapshot action and onchange
handler functionality - please see those patches for details and some
examples.

Thanks,

Tom


The following changes since commit 5a5e3d3ceae2121590d67258a4e658d938b4a46d:

  perf probe: Support SDT markers having reference counter (semaphore) (2018-09-24 04:44:54 -0400)

are available in the git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/zanussi/linux-trace.git ftrace/hist-snapshot-onchange-v5

Tom Zanussi (8):
  tracing: Refactor hist trigger action code
  tracing: Split up onmatch action data
  tracing: Generalize hist trigger onmax and save action
  tracing: Add conditional snapshot
  tracing: Move hist trigger key printing into a separate function
  tracing: Add snapshot action
  tracing: Add hist trigger onchange() handler
  trace: Add alternative synthetic event trace action syntax

 Documentation/trace/histogram.rst                  |  226 +++++
 kernel/trace/trace.c                               |  162 ++-
 kernel/trace/trace.h                               |   56 +-
 kernel/trace/trace_events_hist.c                   | 1062 +++++++++++++++-----
 kernel/trace/trace_events_trigger.c                |    2 +-
 kernel/trace/trace_sched_wakeup.c                  |    2 +-
 .../inter-event/trigger-onchange-action-hist.tc    |   43 +
 .../inter-event/trigger-onmatch-action-hist.tc     |   13 +
 8 files changed, 1280 insertions(+), 286 deletions(-)
 create mode 100644 tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-onchange-action-hist.tc

-- 
2.14.1