Re: [PATCH v2 00/12] tracing: Unifying dynamic event interface

[Masami Hiramatsu]

Ping?

Hi Tom,

This series, especially [09/12] tracing: Remove unneeded synth_event_mutex
will effect your current working series. Please tell me your opinion.

Thank you,

On Mon,  5 Nov 2018 17:59:46 +0900
Masami Hiramatsu <mhiramat@xxxxxxxxxx> wrote:

> 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@xxxxxxxxxx>


-- 
Masami Hiramatsu <mhiramat@xxxxxxxxxx>