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tracing/kprobes: Disable kprobe events by default after creation 

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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

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;