On 2013/4/9 10:16, Steven Rostedt wrote:
> On Tue, 2013-04-09 at 10:08 +0800, zhangwei(Jovi) wrote:
>> On 2013/4/9 4:49, Steven Rostedt wrote:
>>> From: "Steven Rostedt (Red Hat)" <rostedt@xxxxxxxxxxx>
>>>
>>> The function tracing control loop used by perf spits out a warning
>>> if the called function is not a control function. This is because
>>> the control function references a per cpu allocated data structure
>>> on struct ftrace_ops that is not allocated for other types of
>>> functions.
>>>
>>> commit 0a016409e42 "ftrace: Optimize the function tracer list loop"
>>>
>>> Had an optimization done to all function tracing loops to optimize
>>> for a single registered ops. Unfortunately, this allows for a slight
>>> race when tracing starts or ends, where the stub function might be
>>> called after the current registered ops is removed. In this case we
>>> get the following dump:
>>>
>
>> Involve stable? 3.8 kernel user would need this fix.
>
> Why? commit 0a016409e42 "ftrace: Optimize the function tracer list loop"
> was added for 3.9. 3.8 has:
>
> op = rcu_dereference_raw(ftrace_control_list);
> while (op != &ftrace_list_end) {
> if (!ftrace_function_local_disabled(op) &&
> ftrace_ops_test(op, ip))
> op->func(ip, parent_ip, op, regs);
>
> op = rcu_dereference_raw(op->next);
> };
>
> The stub function will never get called.
>
> -- Steve
Hmm, You are right, I misunderstand tag info got by git describe in my local box
[root@jovi linux]# git describe 0a016409e42
trace-3.8-rc4-fix-19-g0a01640
>
>
>
>
> .
>
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