Re: [PATCH v12 3/3] tracing: Centralize preemptirq tracepoints and unify their usage

[Joel Fernandes]

On August 7, 2018 9:49:54 AM EDT, Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
>On Tue, 7 Aug 2018 06:33:35 -0700
>Joel Fernandes <joelaf@xxxxxxxxxx> wrote:
>
>> Thanks, also one more thing I noticed in your patch,
>> lockdep_hardirqs_off needs to be called before all other probes but
>> you're calling it after. This is why I registered it with INT_MAX:
>> 
>> register_trace_prio_irq_disable(lockdep_hardirqs_off, NULL, INT_MAX);
>> 
>> Without it you may get annotation warnings. Thanks,
>
>Interesting. I was following the old way where we called the tracing
>code before calling the lockdep code (all hard coded and not from
>trace events). Is this have something to do with calling the code from
>a tracepoint?
>
>Do you have an example that could trigger the warning?
>

I remember the warnings but can't remember now how I triggered them. I think I saw them with the irqsoff tracer or irq trace events running, with lockdep turned on.

Also an irq disable probe that does a lockdep assert that irqs are disabled could trigger it?

thanks,

- Joel


>-- Steve

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