From 5a0d9050db4d1147722b42afef9011251b2651ee Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Mon, 14 Sep 2009 16:49:37 -0400 Subject: [PATCH] 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 Acked-by: Steven Rostedt Cc: Jim Keniston Cc: Ananth N Mavinakayanahalli Cc: Andi Kleen Cc: Christoph Hellwig Cc: Frank Ch. Eigler Cc: Frederic Weisbecker Cc: H. Peter Anvin Cc: Ingo Molnar Cc: Jason Baron Cc: K.Prasad Cc: Lai Jiangshan Cc: Li Zefan Cc: Peter Zijlstra Cc: Srikar Dronamraju Cc: Tom Zanussi LKML-Reference: <20090914204937.18779.59422.stgit@dhcp-100-2-132.bos.redhat.com> Signed-off-by: Frederic Weisbecker --- Documentation/trace/kprobetrace.txt | 11 +++++++++-- kernel/trace/trace_kprobe.c | 4 ++-- 2 files changed, 11 insertions(+), 4 deletions(-) diff --git a/Documentation/trace/kprobetrace.txt b/Documentation/trace/kprobetrace.txt index 6521681..9b8f7c6 100644 --- a/Documentation/trace/kprobetrace.txt +++ b/Documentation/trace/kprobetrace.txt @@ -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 diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c index d8db935..f6821f1 100644 --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -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; -- 1.8.2.3