Commit 69f08d39 authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Paul E. McKenney
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rcu/tree: Use static initializer for krc.lock 



The per-CPU variable is initialized at runtime in
kfree_rcu_batch_init(). This function is invoked before
'rcu_scheduler_active' is set to 'RCU_SCHEDULER_RUNNING'.
After the initialisation, '->initialized' is to true.

The raw_spin_lock is only acquired if '->initialized' is
set to true. The worqueue item is only used if 'rcu_scheduler_active'
set to RCU_SCHEDULER_RUNNING which happens after initialisation.

Use a static initializer for krc.lock and remove the runtime
initialisation of the lock. Since the lock can now be always
acquired, remove the '->initialized' check.

Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: default avatarUladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent 952371d6

kernel/rcu/tree.c

+6 −7
Original line number Diff line number Diff line
@@ -3002,7 +3002,7 @@ struct kfree_rcu_cpu_work { 
 * @lock: Synchronize access to this structure

 * @monitor_work: Promote @head to @head_free after KFREE_DRAIN_JIFFIES

 * @monitor_todo: Tracks whether a @monitor_work delayed work is pending

 * @initialized: The @lock and @rcu_work fields have been initialized

 * @initialized: The @rcu_work fields have been initialized

 * @count: Number of objects for which GP not started

 *

 * This is a per-CPU structure.  The reason that it is not included in
@@ -3022,7 +3022,9 @@ struct kfree_rcu_cpu { 
	int count;

};



static DEFINE_PER_CPU(struct kfree_rcu_cpu, krc);

static DEFINE_PER_CPU(struct kfree_rcu_cpu, krc) = {

	.lock = __RAW_SPIN_LOCK_UNLOCKED(krc.lock),

};



static __always_inline void

debug_rcu_bhead_unqueue(struct kfree_rcu_bulk_data *bhead)
@@ -3042,7 +3044,6 @@ krc_this_cpu_lock(unsigned long *flags) 


	local_irq_save(*flags);	// For safely calling this_cpu_ptr().

	krcp = this_cpu_ptr(&krc);

	if (likely(krcp->initialized))

	raw_spin_lock(&krcp->lock);



	return krcp;
@@ -3051,7 +3052,6 @@ krc_this_cpu_lock(unsigned long *flags) 
static inline void

krc_this_cpu_unlock(struct kfree_rcu_cpu *krcp, unsigned long flags)

{

	if (likely(krcp->initialized))

	raw_spin_unlock(&krcp->lock);

	local_irq_restore(flags);

}
@@ -4278,7 +4278,6 @@ static void __init kfree_rcu_batch_init(void) 
	for_each_possible_cpu(cpu) {

		struct kfree_rcu_cpu *krcp = per_cpu_ptr(&krc, cpu);



		raw_spin_lock_init(&krcp->lock);

		for (i = 0; i < KFREE_N_BATCHES; i++) {

			INIT_RCU_WORK(&krcp->krw_arr[i].rcu_work, kfree_rcu_work);

			krcp->krw_arr[i].krcp = krcp;

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