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rcu-tasks: Replace exit_tasks_rcu_start() initialization with WARN_ON_ONCE()

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Because the Tasks RCU ->rtp_exit_list is initialized at rcu_init()
time while there is only one CPU running with interrupts disabled, it
is not possible for an exiting task to encounter an uninitialized list.
This commit therefore replaces the conditional initialization with
a WARN_ON_ONCE().

Reported-by: Frederic Weisbecker <frederic@kernel.org>
Closes: https://lore.kernel.org/all/ZdiNXmO3wRvmzPsr@lothringen/
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
This commit is contained in:
Paul E. McKenney 2024-02-23 17:07:24 -08:00 committed by Uladzislau Rezki (Sony)
parent c342b42fa4
commit 8db610c3bd
1 changed files with 1 additions and 2 deletions
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3
kernel/rcu/tasks.h
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@ -1203,8 +1203,7 @@ void exit_tasks_rcu_start(void)
rtpcp = this_cpu_ptr(rcu_tasks.rtpcpu); rtpcp = this_cpu_ptr(rcu_tasks.rtpcpu);
t->rcu_tasks_exit_cpu = smp_processor_id(); t->rcu_tasks_exit_cpu = smp_processor_id();
raw_spin_lock_irqsave_rcu_node(rtpcp, flags); raw_spin_lock_irqsave_rcu_node(rtpcp, flags);
if (!rtpcp->rtp_exit_list.next) WARN_ON_ONCE(!rtpcp->rtp_exit_list.next);
INIT_LIST_HEAD(&rtpcp->rtp_exit_list);
list_add(&t->rcu_tasks_exit_list, &rtpcp->rtp_exit_list); list_add(&t->rcu_tasks_exit_list, &rtpcp->rtp_exit_list);
raw_spin_unlock_irqrestore_rcu_node(rtpcp, flags); raw_spin_unlock_irqrestore_rcu_node(rtpcp, flags);
preempt_enable(); preempt_enable();