[PATCH v3 0/7] tracing: Hist trigger snapshot and onchange additions

From: Tom Zanussi
Date: Thu Aug 09 2018 - 10:34:44 EST

From: Tom Zanussi <tom.zanussi@xxxxxxxxxxxxxxx>


This is v3 of the hist trigger snapshot and onchange additions
patchset. It's rebased on top of the latest ftrace/core and adds a
few fixes to some handler/action problems I noticed while testing.

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
- 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

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



The following changes since commit 5248ee85603067e62a228402afd2fb68f957746b:

tracefs: Annotate tracefs_ops with __ro_after_init (2018-07-31 11:32:44 -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-v3

Tom Zanussi (7):
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

Documentation/trace/histogram.txt | 206 +++++++
kernel/trace/trace.c | 162 +++++-
kernel/trace/trace.h | 58 +-
kernel/trace/trace_events_hist.c | 1008 ++++++++++++++++++++++++++---------
kernel/trace/trace_events_trigger.c | 2 +-
kernel/trace/trace_sched_wakeup.c | 2 +-
6 files changed, 1163 insertions(+), 275 deletions(-)