[PATCH v8 0/4] tracing: Add and use event_command parsing func helpers

Tom Zanussi
2022-02-04T22:12:25Z

With more event commands being implemented, it's been pointed out that
it would make sense to clean up the existing ones and make it easier
to implement new ones without copying a lot of boilerplate. The main
culprit here is the event_command.func() callback - the rest of the
event_command infrastructure has default implementations that work for
most implementations. The func() callback is a little different in
that every new command needs to customize parsing to some extent.

This patchset attempts to help clean that up and make it easier for
new users to deal with.

v8: Patches 1-4 of v7 were merged and so don't appear here.

Added new patch 'tracing: Remove logic for registering multiple
event triggers at a time' because the code doesn't ever register
multiple triggers and it just complicates the code. Doing this
also removes the unreg() call along with just about everything
else from event_trigger_register() so is no longer a policy
violation. Also added a new function event_trigger_unregister()
to match event_trigger_register() and clean up the code even more.

Moved 'tracing: Remove redundant trigger_ops params' so it doesn't
depend on the following patches.

Added 'tracing: Separate hist state updates from hist
registration' to remove the confusing logic concerning
pause/cont/clear and which caused problems in v7.

v7: Missed a fixup in patch 6/6 to a data->ops->print() in the debug
code since I forgot to build with CONFIG_HIST_TRIGGERS_DEBUG.

Patches 1-5 remain the same.

v6: Fixed warning for an uninitialized trigger_ops local in
event_trigger_parse() pointed out by Steve and the kernel test
robot. This was done by removing the need for the local by
removing the redundant trigger_ops params in [PATCH v6 3/6]
tracing: Remove ops param from event_command reg()/unreg()
callbacks.

Also added a follow-on patch to remove all the other instances of
redundant trigger_ops in [PATCH v6 6/6] tracing: Remove redundant
trigger_ops params

v5: Changed the parsing helper function example components param and
filter to reflect only the param and filter components, and added
param_and_filter which now appears in the functions.

Removed the check for a NULL *param following the strsep
separating the param from the filter in
event_trigger_separate_filter() because it will never be true due
to the previous check for NULL param_and_filter previously.

Changed the param name from trigger to param and updated the
function documentation in event_trigger_parse_num().

v4: Added two patches changing the names of event_command.func() and
event_trigger_ops.func() to make them reflect their functions.

Added back missing kfree(trigger_data) in event_trigger_callback().

Changed char *param to const char *param in
event_trigger_check_remove() and event_trigger_empty_param().

Changed event_trigger_separate_filter() to use separate param and
filter outparams, and changed the name of the param inparam to
param_and_filter to better reflect its contents and avoid the
clash with new param outparam. Changed all parse()
implementations to use this new scheme.

Fixed some typos and added more extensive comments with examples
explaining various things that were mentioned as causing confusion
and just in general tried to clarify things with respect to the
callbacks and parameters.

v3: broke up event_trigger_check() into smaller functions instead of
parameterizing it, and added function documentation.

v2: removed unused event_trigger_remove(). No change in functionality.

The following changes since commit f125ef075cd648a7794aa0cc61a188b1c40c8f94:

tracing: Remove size restriction on synthetic event cmd error logging (2022-01-27 19:15:51 -0500)

are available in the Git repository at:

git://git.kernel.org/pub/scm/linux/kernel/git/zanussi/linux-trace.git ftrace/cleanup-hist-func-v8

Tom Zanussi (4):
tracing: Remove logic for registering multiple event triggers at a
time
tracing: Remove redundant trigger_ops params
tracing: Have existing event_command.parse() implementations use
helpers
tracing: Separate hist state updates from hist registration

kernel/trace/trace.h | 26 ++-
kernel/trace/trace_eprobe.c | 10 +-
kernel/trace/trace_events_hist.c | 166 ++++++++--------
kernel/trace/trace_events_trigger.c | 292 +++++++++-------------------
4 files changed, 193 insertions(+), 301 deletions(-)

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2.17.1