[PATCH v11 0/1] Tracepoint API simplification, text size shrink

[Mathieu Desnoyers]

Here is v11 of the tracepoint register/unregister API simplification,
submitted for 3.15.

This removes 8.8kB to the size of vmlinux (mostly text).

Changes since v1:
- Adapt ftrace/perf callers,
- Update tracepoint.h macro,
- Build tested.

Changes since v2:
- Introduce for_each_tracepoint() iterator to allow listing the
  currently loaded tracepoints, for modules using coming/going
  notifiers to track tracepoints.

Changes since v3:
- Introduce module coming and going notifiers each with their own
  priority to ensure that other coming notifiers are called after, and
  coming notifiers are called before the tracepoint notifiers.
- Fix: move for_each_tracepoint() outside of the CONFIG_MODULE ifdef.

Changes since v4:
- Split tracepoints_mutex into two locks: tp_modlist_mutex, which
  protects the tracepoint list of modules, and a tracepoint_mutex, which
  protects the tracepoints per se. tracepoint_mutex nests inside
  tp_modlist_mutex.
- Introduce a tracepoint module notifier, to ensure consistency between
  iteration on tracepoints with for_each_tracepoint() and module coming
  and going notifications. This consistency is ensured by holding
  tp_modlist_mutex when calling the notifier and when iterating on the
  tracepoint module list.

Changes since v5:
- Remove tracepoint_add_old_probes within "Tracepoint cleanup: remove
  unused API functions" rather than in later patch.
- Remove struct tp_probes "old probes" list within "Tracepoint cleanup:
  remove unused API functions", as it is not needed anymore.
- Within "Tracepoint cleanup: remove unused API functions", simply add
  the new module to tail of list, since there is no need to keep it
  ordered anymore.

Changes since v6:
- Remove unused struct list_head list from struct tp_probes in patch
  "Tracepoint: register/unregister struct tracepoint",
- Rename for_each_tracepoint() to for_each_kernel_tracepoint(). Only
  iterate on kernel tracepoints,
- Registered tracepoint module notifiers now receive struct tp_module
  pointer rather than struct module pointer,
- register_tracepoint_module_notifier and
  unregister_tracepoint_module_notifier now iterate on all modules and
  call coming/going notifiers. This ensures notifier registration and
  listing of already loaded modules are done atomically (protected by
  tp_modlist_mutex).

Changes since v7:
- Coding style updates,
- Shrink size of ftrace/perf struct ftrace_event_call,
- Put back the original tracepoints_mutex name, keep an original comment
  layout that goes beyond 80 columns, put back original
  tracepoint_module_list name, and rename tp_modlist_mutex to
  tracepoint_module_list_mutex, so this patch does not introduce
  cosmetic changes to pre-existing code.

Changes since v8:
- Use anonymous union in struct ftrace_event_call,
- Check for NULL call->tp in ftrace_event_get_name().

Changes since v9:
- Fix __TRACE_EVENT_FLAGS() to add flag rather set it. This was
  triggering the WARN_ON() safety net added into ftrace_event_reg() by
  this patch.

Changes since v10:
- Rename ftrace_event_get_name to ftrace_event_name,
- Add 2 missing call->name to ftrace_event_name(call) changes. Tested
  with allyesconfig and allmodconfig along with a temporary field name
  swap from name to _name to ensure no other sites are missing.

Thanks!

Mathieu


Mathieu Desnoyers (1):
  Tracepoint: register/unregister struct tracepoint

 include/linux/ftrace_event.h        |   22 +-
 include/linux/tracepoint.h          |   41 +--
 include/trace/ftrace.h              |    9 +-
 kernel/trace/trace_events.c         |   55 ++--
 kernel/trace/trace_events_trigger.c |    2 +-
 kernel/trace/trace_kprobe.c         |   21 +-
 kernel/trace/trace_output.c         |    2 +-
 kernel/trace/trace_uprobe.c         |   20 +-
 kernel/tracepoint.c                 |  509 +++++++++++++++--------------------
 9 files changed, 330 insertions(+), 351 deletions(-)

-- 
1.7.10.4

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