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author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-09-20 21:01:22 -0700 |
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committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-09-20 21:01:22 -0700 |
commit | 19a5ecde086a6a5287978b12ae948fa691b197b7 (patch) | |
tree | dea41c8c9a9f6f0978b663090c382a2f23d4f189 /Documentation/locking | |
parent | 66e8c57da6bf6b847a48a5a6fda59512f733ed78 (diff) | |
download | op-kernel-dev-19a5ecde086a6a5287978b12ae948fa691b197b7.zip op-kernel-dev-19a5ecde086a6a5287978b12ae948fa691b197b7.tar.gz |
rcu: Suppress lockdep false positive for rcp->exp_funnel_mutex
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>
Diffstat (limited to 'Documentation/locking')
0 files changed, 0 insertions, 0 deletions