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In kernels built with CONFIG_PREEMPT=y, synchronize_rcu_expedited() invokes synchronize_sched_expedited() while holding RCU-preempt's root rcu_node structure's ->exp_funnel_mutex, which is acquired after the rcu_data structure's ->exp_funnel_mutex. The first thing that synchronize_sched_expedited() will do is acquire RCU-sched's rcu_data structure's ->exp_funnel_mutex. There is no danger of an actual deadlock because the locking order is always from RCU-preempt's expedited mutexes to those of RCU-sched. Unfortunately, lockdep considers both rcu_data structures' ->exp_funnel_mutex to be in the same lock class and therefore reports a deadlock cycle. This commit silences this false positive by placing RCU-sched's rcu_data structures' ->exp_funnel_mutex locks into their own lock class. Reported-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> |
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| .. | ||
| Makefile | ||
| rcu.h | ||
| rcutorture.c | ||
| srcu.c | ||
| tiny.c | ||
| tiny_plugin.h | ||
| tree.c | ||
| tree.h | ||
| tree_plugin.h | ||
| tree_trace.c | ||
| update.c | ||