Messages in this thread | | | Subject | Re: [PATCH] tracing/uprobes: Support ftrace_event_file base multibuffer | From | Steven Rostedt <> | Date | Fri, 14 Jun 2013 12:33:27 -0400 |
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On Fri, 2013-06-14 at 09:21 -0700, Paul E. McKenney wrote:
> > > > @@ -548,15 +556,35 @@ static void uprobe_trace_print(struct trace_uprobe *tu, > > > > /* uprobe handler */ > > > > static int uprobe_trace_func(struct trace_uprobe *tu, struct pt_regs *regs) > > > > { > > > > - if (!is_ret_probe(tu)) > > > > - uprobe_trace_print(tu, 0, regs); > > > > + struct ftrace_event_file **file; > > > > + > > > > + if (is_ret_probe(tu)) > > > > + return 0; > > > > + > > > > + file = rcu_dereference_raw(tu->files); > > > > Why are you using rcu_dereference_raw() and not rcu_dereference(). The > > _raw() is a bit special, and unless you know what you are doing with RCU > > here, don't use it. > > > > As I see you using rcu_dereference_raw() all over this patch, along with > > mutexes, I believe that you are not using RCU correctly here. > > If irqs and preempt are disabled, I suggest using rcu_dereference_sched(). > That is what it is there for. ;-) >
I believe this just copied what kprobes did, where irqs and preemption is disabled. I don't believe that these probes have that same luxury.
But that begs the question. Should we convert the rcu_dereference_raw() in the kprobe code to rcu_dereference_sched()?
-- Steve
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