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Subject[PATCH v2 00/12] tracing: Unifying dynamic event interface
Date
Hi,

This is v2 series of unifying dynamic event interface on ftrace.
Currently ftrace has 3 dynamic event interfaces, kprobes, uprobes
and synthetic. This series unifies those dynamic event interfaces
to "dynamic_events" so that we can add other dynamic events easily
on same interface, e.g. function events.
The older interfaces are left on the tracefs for backward
compatibility.

dynamic_events syntax has no difference from kprobe_events and
uprobe_events. You can use same syntax for dynamic_events interface.
For synthetic events, similar to the probe events, dynamic_events
adds "s:[GROUP/]" prefix, where the "GROUP/" must be "synthetic/".

s:[synthetic/]<event-name> type arg [type arg]...

E.g.

$ echo 'wakeup_latency u64 lat pid_t pid char' > synthetic_events

is same as

$ echo 's:wakeup_latency u64 lat pid_t pid char' > dynamic_events

Or

$ echo 's:synthetic/wakeup_latency u64 lat pid_t pid char' > dynamic_events

This series modifies synthetic event interface behavior a bit,
reorder lock dependency and related cleanups so that we can integrate
the synthetic event to dynamic_events interface.

In this version, I changed the generic '!' erase command, which
now supports entire line style like other interfaces. So you can
delete events via dynamic_events as below

$ cat dynamic_events | while read line; \
do echo "!$line" >> dynamic_events; done

Also, the big change will be removing dyn_event_mutex and
synth_event_mutex because all those parts are protected by
event_mutex.

Changes from v2 are here;

New patches:
- Reorder event_mutex and synth_event_mutex to solve
AB-BA deadlock correctly. ([2/12])
- Simplify creation and deletion of synthetic event. ([3/12])
- Retern -ENOENT if there is no synthetic event when deleting ([4/12])
- Integrate similar probe argument parsers ([5/12])
- Use dyn_event framework for synthetic events ([9/12])
- Remove synth_event_mutex ([10/12])
- Remove unused APIs ([11/12])

Modified patches:
[6/12] - [8/12]
- Generalize delete event and export as dyn_event_release_all().
- Add match operation for find deleting event.
- Reorder event_mutex and dyn_event_mutex to solve lock dependency
issue.
- Pass const char **argv for create operation and use -ECANCELED to
signal for trying next dyn_event_operations.
- Remove dyn_event_mutex.

[12/12]
- Accept entire line, but instead of checking the given entire line
strictly, simply checking the event and group name.

Tom, thanks for your Ack for v1 series. Since I changed many things
from v1 (not only minor change), I decided to not add your Ack for
this version. Anyway, what I've added in this version are related to
synthetic events. I need your review for those.
(especially removing synth_event_mutex)

You can try it from my git tree.

https://github.com/mhiramat/linux/tree/unify-dynamic-events-v2

Thank you,

---

Masami Hiramatsu (12):
tracing/uprobes: Add busy check when cleanup all uprobes
tracing: Lock event_mutex before synth_event_mutex
tracing: Simplify creation and deletion of synthetic event
tracing: Integrate similar probe argument parsers
tracing: Add unified dynamic event framework
tracing/kprobes: Use dyn_event framework for kprobe events
tracing/uprobes: Use dyn_event framework for uprobe events
tracing: Use dyn_event framework for synthetic events
tracing: Remove unneeded synth_event_mutex
tracing: Remove orphaned trace_add/remove_event_call functions
tracing: Add generic event-name based remove event method
selftests/ftrace: Add testcases for dynamic event


Documentation/trace/kprobetrace.rst | 3
Documentation/trace/uprobetracer.rst | 4
include/linux/trace_events.h | 4
kernel/trace/Kconfig | 6
kernel/trace/Makefile | 1
kernel/trace/trace.c | 12 +
kernel/trace/trace_dynevent.c | 217 ++++++++++++
kernel/trace/trace_dynevent.h | 119 +++++++
kernel/trace/trace_events.c | 12 -
kernel/trace/trace_events_hist.c | 322 ++++++++++--------
kernel/trace/trace_kprobe.c | 357 ++++++++++----------
kernel/trace/trace_probe.c | 74 ++++
kernel/trace/trace_probe.h | 9 -
kernel/trace/trace_uprobe.c | 305 ++++++++---------
.../ftrace/test.d/dynevent/add_remove_kprobe.tc | 30 ++
.../ftrace/test.d/dynevent/add_remove_synth.tc | 27 ++
.../ftrace/test.d/dynevent/clear_select_events.tc | 50 +++
.../ftrace/test.d/dynevent/generic_clear_event.tc | 49 +++
18 files changed, 1094 insertions(+), 507 deletions(-)
create mode 100644 kernel/trace/trace_dynevent.c
create mode 100644 kernel/trace/trace_dynevent.h
create mode 100644 tools/testing/selftests/ftrace/test.d/dynevent/add_remove_kprobe.tc
create mode 100644 tools/testing/selftests/ftrace/test.d/dynevent/add_remove_synth.tc
create mode 100644 tools/testing/selftests/ftrace/test.d/dynevent/clear_select_events.tc
create mode 100644 tools/testing/selftests/ftrace/test.d/dynevent/generic_clear_event.tc

--
Masami Hiramatsu (Linaro) <mhiramat@kernel.org>

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