Messages in this thread Patch in this message | | | Date | Mon, 29 Jul 2019 21:59:43 -0400 | From | Steven Rostedt <> | Subject | Re: [PATCH] tracing: Prevent RCU EQS breakage in preemptirq events |
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On Tue, 30 Jul 2019 10:50:36 +0900 Eiichi Tsukata <devel@etsukata.com> wrote:
> > > > I think they already (try to) do that; see 'tracing_irq_cpu'. > > > > Or you mean something like this? > As for trace_hardirqs_off_caller:
You missed what Peter said.
> > diff --git a/kernel/trace/trace_preemptirq.c b/kernel/trace/trace_preemptirq.c > index 4d8e99fdbbbe..d39478bcf0f2 100644 > --- a/kernel/trace/trace_preemptirq.c > +++ b/kernel/trace/trace_preemptirq.c > @@ -66,7 +66,7 @@ __visible void trace_hardirqs_off_caller(unsigned long caller_addr) > if (!this_cpu_read(tracing_irq_cpu)) { ^^^^^^^^^^^^^^^ The above makes this called only the first time we disable interrupts.
> this_cpu_write(tracing_irq_cpu, 1); > tracer_hardirqs_off(CALLER_ADDR0, caller_addr); > - if (!in_nmi()) > + if (!in_nmi() && !irqs_disabled())
This would always be false. This function is always called with irqs_disabled()!
So no, this is not what is meant.
> trace_irq_disable_rcuidle(CALLER_ADDR0, caller_addr); > } > > Or > > diff --git a/kernel/trace/trace_preemptirq.c b/kernel/trace/trace_preemptirq.c > index 4d8e99fdbbbe..e08c5c6ff2b3 100644 > --- a/kernel/trace/trace_preemptirq.c > +++ b/kernel/trace/trace_preemptirq.c > @@ -66,8 +66,6 @@ __visible void trace_hardirqs_off_caller(unsigned long caller_addr) > if (!this_cpu_read(tracing_irq_cpu)) { > this_cpu_write(tracing_irq_cpu, 1); > tracer_hardirqs_off(CALLER_ADDR0, caller_addr); > - if (!in_nmi()) > - trace_irq_disable_rcuidle(CALLER_ADDR0, caller_addr);
And this just removes the tracepoint completely?
-- Steve
> } > > > As for trace_hardirqs_on_caller, it is called when IRQs off and CONTEXT_USER. > So even though we skipped the trace event if the previous state was already IRQs on, > we will fall into the same situation.
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