Re: suspicious RCU usage warnings in 3.3.0
From: David Miller
Date: Wed Apr 11 2012 - 21:13:45 EST
From: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>
Date: Wed, 11 Apr 2012 17:45:07 -0700
> If I am confused about the simple function call, and if control is really
> passing via an interrupt or exception, then rcu_irq_enter() should be
> called on entry to the interrupt or exception and rcu_irq_exit() should
> be called on exit.
Hmm, it seems the convention changed such that platforms aren't
supposed to invoke do_softirq() from their trap return trap any more.
It's handled completely by irq_exit().
When did that start happening? :-)
Anyways I bet that's the problem, sparc64 invokes do_softirq() in it's
trap return path if softirqs are pending, and that doesn't do any
of the RCU frobbing you mention.
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