From 69f08d3999dbef1553a3332b8055282dd3893b6c Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Mon, 25 May 2020 23:47:51 +0200 Subject: [PATCH] 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 Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Uladzislau Rezki (Sony) Signed-off-by: Paul E. McKenney --- kernel/rcu/tree.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 368bdc441ffb..a42a4693f161 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -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) @@ -3042,8 +3044,7 @@ 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); + raw_spin_lock(&krcp->lock); return krcp; } @@ -3051,8 +3052,7 @@ 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); + 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;