rcu/nocb: Introduce nocb mutex

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The barrier_mutex is used currently to protect (de-)offloading
operations and prevent from nocb_lock locking imbalance in rcu_barrier()
and shrinker, and also from misordered RCU barrier invocation.

Now since RCU (de-)offloading is going to happen on offline CPUs, an RCU
barrier will have to be executed while transitionning from offloaded to
de-offloaded state. And this can't happen while holding the
barrier_mutex.

Introduce a NOCB mutex to protect (de-)offloading transitions. The
barrier_mutex is still held for now when necessary to avoid barrier
callbacks reordering and nocb_lock imbalance.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>

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Frederic Weisbecker 2024-05-30 15:45:45 +02:00 • committed by Neeraj Upadhyay

parent 7be88a857e

commit 7121dd915a

4 changed files with 17 additions and 8 deletions

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3

kernel/rcu/tree.c

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1

kernel/rcu/tree.h

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20

kernel/rcu/tree_nocb.h

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1

kernel/rcu/tree_plugin.h

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