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From: Joel Fernandes <joel@joelfernandes.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org, kernel-team@android.com,
	Boqun Feng <boqun.feng@gmail.com>,
	Byungchul Park <byungchul.park@lge.com>,
	Erick Reyes <erickreyes@google.com>,
	Ingo Molnar <mingo@redhat.com>, Julia Cartwright <julia@ni.com>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Namhyung Kim <namhyung@kernel.org>,
	Paul McKenney <paulmck@linux.vnet.ibm.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Thomas Glexiner <tglx@linutronix.de>,
	Todd Kjos <tkjos@google.com>,
	Tom Zanussi <tom.zanussi@linux.intel.com>,
	Will Deacon <will.deacon@arm.com>
Subject: Re: [PATCH v11 3/3] tracing: Centralize preemptirq tracepoints and unify their usage
Date: Mon, 30 Jul 2018 12:18:55 -0700	[thread overview]
Message-ID: <20180730191855.GA46892@joelaf.mtv.corp.google.com> (raw)
In-Reply-To: <20180730085813.GB2494@hirez.programming.kicks-ass.net>

On Mon, Jul 30, 2018 at 10:58:13AM +0200, Peter Zijlstra wrote:
> On Thu, Jul 26, 2018 at 04:50:44PM -0700, Joel Fernandes wrote:
> > One note, I have to check for lockdep recursion in the code that calls
> > the trace events API and bail out if we're in lockdep recursion
> > protection to prevent something like the following case: a spin_lock is
> > taken. Then lockdep_acquired is called.  That does a raw_local_irq_save
> > and then sets lockdep_recursion, and then calls __lockdep_acquired. In
> > this function, a call to get_lock_stats happens which calls
> > preempt_disable, which calls trace IRQS off somewhere which enters my
> > tracepoint code and sets the tracing_irq_cpu flag to prevent recursion.
> > This flag is then never cleared causing lockdep paths to never be
> > entered and thus causing splats and other bad things.
> 
> That is now fixed, right?

Yes, that's right it got fixed from v9->v10 but I forgot to update the
changelog, I'll make the change and resend. Thanks!

thanks,

- Joel


  reply	other threads:[~2018-07-30 19:19 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-26 23:50 [PATCH v11 0/3] tracing: Centralize preemptirq tracepoints and unify their usage Joel Fernandes
2018-07-26 23:50 ` [PATCH v11 1/3] lockdep: use this_cpu_ptr instead of get_cpu_var stats Joel Fernandes
2018-07-26 23:50 ` [PATCH v11 2/3] tracepoint: Make rcuidle tracepoint callers use SRCU Joel Fernandes
2018-07-27 16:26   ` Steven Rostedt
2018-07-27 18:51     ` Joel Fernandes
2018-07-27 18:57       ` Steven Rostedt
2018-07-27 21:47         ` Joel Fernandes
2018-07-26 23:50 ` [PATCH v11 3/3] tracing: Centralize preemptirq tracepoints and unify their usage Joel Fernandes
2018-07-27 16:28   ` Steven Rostedt
2018-07-27 18:55     ` Joel Fernandes
2018-07-30  8:58   ` Peter Zijlstra
2018-07-30 19:18     ` Joel Fernandes [this message]
2018-07-30  8:59 ` [PATCH v11 0/3] " Peter Zijlstra
2018-07-30 19:25   ` Joel Fernandes
2018-07-30 22:00     ` Steven Rostedt

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