(2013/06/18 0:18), Oleg Nesterov wrote: > On 06/17, Masami Hiramatsu wrote: >> >> (2013/06/17 2:21), Oleg Nesterov wrote: >>> enable_trace_probe() and disable_trace_probe() should not worry about >>> serialization, the caller (perf_trace_init or __ftrace_set_clr_event) >>> holds event_mutex. >>> >>> They are also called by kprobe_trace_self_tests_init(), but this __init >>> function can't race with itself or trace_events.c >> >> Right, >> For safety, we should comment this at the caller side, > > Which caller do you mean?
I meant the caller was kprobe_test_self_tests_init(). Since that function calls enable/disable_trace_probe() without holding event_mutex, we need to notice that (this is safe because there is no race) at the calling places :) Thank you, > > The patch adds > > /* > * This and enable_trace_probe/disable_trace_probe rely on event_mutex > * held by the caller, __ftrace_set_clr_event(). > */ > > above trace_probe_nr_files() but the next patch removes this function > with the comment... > > Will you agree with this patch if I add something like > > /* > * called by perf_trace_init() or __ftrace_set_clr_event() under > event_mutex > */ > > above kprobe_register() ? Perhaps it makes sense to add > lockdep_assert_held(&event_mutex) into the body? > > And: > >> because >> those calls are the reason why I have introduced this lock. > > Please do not hesitate to nack this patch if you think that we should > keep probe_enable_lock for safety even if it is not currently needed. > In this case I'd suggest to move lock/unlock into kprobe_register() > but this is minor. > > Oleg. > > -- Masami HIRAMATSU IT Management Research Dept. Linux Technology Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu...@hitachi.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
