Re: [PATCH RFC tip/core/rcu 22/41] rcu: Simplify unboosting checks

From: Josh Triplett
Date: Wed Feb 01 2012 - 21:39:12 EST


On Wed, Feb 01, 2012 at 11:41:40AM -0800, Paul E. McKenney wrote:
> From: "Paul E. McKenney" <paul.mckenney@xxxxxxxxxx>
>
> This is a port of commit #82e78d80 from TREE_PREEMPT_RCU to
> TINY_PREEMPT_RCU.
>
> This commit uses the fact that current->rcu_boost_mutex is set
> any time that the RCU_READ_UNLOCK_BOOSTED flag is set in the
> current->rcu_read_unlock_special bitmask. This allows tests of
> the bit to be changed to tests of the pointer, which in turn allows
> the RCU_READ_UNLOCK_BOOSTED flag to be eliminated.

Does this change affect rcu_read_unlock()'s logic to trigger the
slowpath only when special flags get set?

- Josh Triplett
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