path: root/kernel/rcu/tree_plugin.h
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authorPaul E. McKenney <>2015-07-19 15:13:40 -0700
committerPaul E. McKenney <>2015-08-04 08:39:21 -0700
commitaf859beaaba4d57883b08f4acbcb3974bc1f975e (patch)
tree0bff1fa9c43693c9f513daf48197be3627b3301c /kernel/rcu/tree_plugin.h
parentcdacbe1f91264687af956e810278030f2ab5a3d0 (diff)
rcu: Silence lockdep false positive for expedited grace periods
In a CONFIG_PREEMPT=y kernel, synchronize_rcu_expedited() acquires the ->exp_funnel_mutex in rcu_preempt_state, then invokes synchronize_sched_expedited, which acquires the ->exp_funnel_mutex in rcu_sched_state. There can be no deadlock because rcu_preempt_state ->exp_funnel_mutex acquisition always precedes that of rcu_sched_state. But lockdep does not know that, so it gives false-positive splats. This commit therefore associates a separate lock_class_key structure with the rcu_sched_state structure's ->exp_funnel_mutex, allowing lockdep to see the lock ordering, avoiding the false positives. Signed-off-by: Paul E. McKenney <>
Diffstat (limited to 'kernel/rcu/tree_plugin.h')
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