Messages in this thread | | | From | Joel Fernandes <> | Date | Fri, 27 Apr 2018 09:30:05 -0700 | Subject | Re: [PATCH RFC] tracepoint: Introduce tracepoint callbacks executing with preempt on |
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On Fri, Apr 27, 2018 at 7:47 AM, Steven Rostedt <rostedt@goodmis.org> wrote: > On Fri, 27 Apr 2018 10:26:29 -0400 (EDT) > Mathieu Desnoyers <mathieu.desnoyers@efficios.com> wrote: > >> The general approach and the implementation look fine, except for >> one small detail: I would be tempted to explicitly disable preemption >> around the call to the tracepoint callback for the rcuidle variant, >> unless we plan to audit every tracer right away to remove any assumption >> that preemption is disabled in the callback implementation. > > I'm thinking that we do that audit. There shouldn't be many instances > of it. I like the idea that a tracepoint callback gets called with > preemption enabled.
Here is the list of all callers of the _rcuidle :
trace_clk_disable_complete_rcuidle trace_clk_disable_rcuidle trace_clk_enable_complete_rcuidle trace_clk_enable_rcuidle trace_console_rcuidle trace_cpu_idle_rcuidle trace_ipi_entry_rcuidle trace_ipi_exit_rcuidle trace_ipi_raise_rcuidle trace_irq_disable_rcuidle trace_irq_enable_rcuidle trace_power_domain_target_rcuidle trace_preempt_disable_rcuidle trace_preempt_enable_rcuidle trace_rpm_idle_rcuidle trace_rpm_resume_rcuidle trace_rpm_return_int_rcuidle trace_rpm_suspend_rcuidle trace_tlb_flush_rcuidle
All of these are either called from irqs or preemption disabled already. So I think it should be fine to keep preemption on. But I'm Ok with disabling it before callback execution if we agree that we want that.
(and the ring buffer code is able to cope anyway Steven pointed).
thanks,
- Joel
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