tracing/filters: improve subsystem filter
authorLi Zefan <lizf@cn.fujitsu.com>
Mon, 20 Jul 2009 02:20:53 +0000 (10:20 +0800)
committerSteven Rostedt <rostedt@goodmis.org>
Mon, 20 Jul 2009 17:29:19 +0000 (13:29 -0400)
commit1f9963cbb0280e0cd554161e00f1a0eeddbf1ae1
tree80e27aa2cf5401fc04f7dbb806ad7e0ec04b6e8c
parentff4e9da2330beb8d64498a513d3f9694e941b01a
tracing/filters: improve subsystem filter

Currently a subsystem filter should be applicable to all events
under the subsystem, and if it failed, all the event filters
will be cleared. Those behaviors make subsys filter much less
useful:

  # echo 'vec == 1' > irq/softirq_entry/filter
  # echo 'irq == 5' > irq/filter
  bash: echo: write error: Invalid argument
  # cat irq/softirq_entry/filter
  none

I'd expect it set the filter for irq_handler_entry/exit, and
not touch softirq_entry/exit.

The basic idea is, try to see if the filter can be applied
to which events, and then just apply to the those events:

  # echo 'vec == 1' > softirq_entry/filter
  # echo 'irq == 5' > filter
  # cat irq_handler_entry/filter
  irq == 5
  # cat softirq_entry/filter
  vec == 1

Changelog for v2:
- do some cleanups to address Frederic's comments.

Inspired-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4A63D485.7030703@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
include/linux/ftrace_event.h
kernel/trace/trace.h
kernel/trace/trace_events_filter.c