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tracing/kprobes: Disable kprobe events by default after creation

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Disable newly created kprobe events by default, not to disturb
another user using ftrace. "Disturb" means when someone is using
ftrace and another user tries to use perf-tools, (in near
future) if he defines new kprobe event via perf-tools, then new
events will mess up the frace buffer. Fix this to allow proper
and transparent kprobes events concurrent usage between ftrace
users and perf users.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Frank Ch. Eigler <fche@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jason Baron <jbaron@redhat.com>
Cc: K.Prasad <prasad@linux.vnet.ibm.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <20090914204937.18779.59422.stgit@dhcp-100-2-132.bos.redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
This commit is contained in:
Masami Hiramatsu 2009-09-14 16:49:37 -04:00 committed by Frederic Weisbecker
parent 74ebb63e7c
commit 5a0d9050db
2 changed files with 11 additions and 4 deletions
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11
Documentation/trace/kprobetrace.txt
View file

@ -122,8 +122,15 @@ print fmt: "(%lx) dfd=%lx filename=%lx flags=%lx mode=%lx", REC->ip, REC->dfd, R
echo > /sys/kernel/debug/tracing/kprobe_events
This clears all probe points. and you can see the traced information via
/sys/kernel/debug/tracing/trace.
This clears all probe points.
Right after definition, each event is disabled by default. For tracing these
events, you need to enable it.
echo 1 > /sys/kernel/debug/tracing/events/kprobes/myprobe/enable
echo 1 > /sys/kernel/debug/tracing/events/kprobes/myretprobe/enable
And you can see the traced information via /sys/kernel/debug/tracing/trace.
cat /sys/kernel/debug/tracing/trace
# tracer: nop

4
kernel/trace/trace_kprobe.c
View file

@ -383,7 +383,7 @@ static int register_trace_probe(struct trace_probe *tp)
goto end;
}
tp->flags = TP_FLAG_TRACE;
tp->rp.kp.flags |= KPROBE_FLAG_DISABLED;
if (probe_is_return(tp))
ret = register_kretprobe(&tp->rp);
else
@ -1298,7 +1298,7 @@ static int register_probe_event(struct trace_probe *tp)
call->id = register_ftrace_event(&tp->event);
if (!call->id)
return -ENODEV;
call->enabled = 1;
call->enabled = 0;
call->regfunc = probe_event_enable;
call->unregfunc = probe_event_disable;