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Date:   Tue, 07 Aug 2018 10:48:05 -0400
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Subject: Re: [PATCH v12 3/3] tracing: Centralize preemptirq tracepoints and unify their usage
To:     Steven Rostedt <rostedt@goodmis.org>
CC:     Joel Fernandes <joel@joelfernandes.org>,
        LKML <linux-kernel@vger.kernel.org>,
        "Cc: Android Kernel" <kernel-team@android.com>,
        Boqun Feng <boqun.feng@gmail.com>,
        Byungchul Park <byungchul.park@lge.com>,
        Ingo Molnar <mingo@redhat.com>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        Namhyung Kim <namhyung@kernel.org>,
        Paul McKenney <paulmck@linux.vnet.ibm.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Thomas Glexiner <tglx@linutronix.de>,
        Tom Zanussi <tom.zanussi@linux.intel.com>
From:   Joel Fernandes <joelaf@google.com>
Message-ID: <C1CB990F-8232-4168-89A8-E8C13B660B0B@google.com>
Sender: linux-kernel-owner@vger.kernel.org
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On August 7, 2018 10:34:10 AM EDT, Steven Rostedt <rostedt@goodmis=2Eorg> =
wrote:
>On Tue, 07 Aug 2018 10:10:59 -0400
>Joel Fernandes <joelaf@google=2Ecom> wrote:
>
>> On August 7, 2018 9:49:54 AM EDT, Steven Rostedt
><rostedt@goodmis=2Eorg> wrote:
>> >On Tue, 7 Aug 2018 06:33:35 -0700
>> >Joel Fernandes <joelaf@google=2Ecom> wrote:
>> > =20
>> >> 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=2E This is why I registered it with INT_MAX:
>> >>=20
>> >> register_trace_prio_irq_disable(lockdep_hardirqs_off, NULL,
>INT_MAX);
>> >>=20
>> >> Without it you may get annotation warnings=2E Thanks, =20
>> >
>> >Interesting=2E 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)=2E Is this have something to do with calling the code
>from
>> >a tracepoint?
>> >
>> >Do you have an example that could trigger the warning?
>> > =20
>>=20
>> I remember the warnings but can't remember now how I triggered them=2E
>> I think I saw them with the irqsoff tracer or irq trace events
>> running, with lockdep turned on=2E
>
>I'll see if I can trigger it=2E I'll run this all through my tests=2E

Ok=2E

>> Also an irq disable probe that does a lockdep assert that irqs are
>> disabled could trigger it?
>>=20
>
>You mean if someone add a tracepoint callback to the irq disable
>tracepoint, and did a lockdep assert to make sure interrupts are
>disabled?

Yes that's what I meant=2E

Thanks,

- Joel

--=20
Sent from my Android device with K-9 Mail=2E Please excuse my brevity=2E