Messages in this thread | | | Date | Wed, 16 Dec 2009 07:18:48 -0800 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH RFC tip/core/rcu 18/18] rcu: add primitives to check for RCU read-side critical sections |
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On Wed, Dec 16, 2009 at 11:31:34AM +0100, Peter Zijlstra wrote: > On Tue, 2009-12-15 at 15:02 -0800, Paul E. McKenney wrote: > > > > Also create rcu_dereference_check(), which takes a second boolean argument > > into which one puts rcu_read_lock_held() or similar. For example: > > > > rcu_dereference_check(gp, rcu_read_lock_held() || > > lockdep_is_held(my_lock)); > > Ah, so you're going to tackle this the other way around, interesting :-)
Still feeling my way around this one, but for the moment, yes. ;-)
One potential issue is that for lockdep, avoiding false positives means erring on the side of the lock -not- being held, while for this approach to rcu_dereference() checking, avoiding false positives means erring on the side of the lock being held.
I might need to create a CONFIG_PROVE_LOCKING_RCU to allow shutting off the more-detailed RCU checking when people want to do partial deadlock checking, but will see how it goes.
Thanx, Paul
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