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[94.245.46.49]) by smtp.gmail.com with ESMTPSA id a6sm2280044lji.29.2020.05.25.14.48.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 25 May 2020 14:48:17 -0700 (PDT) From: "Uladzislau Rezki (Sony)" To: LKML , linux-mm@kvack.org Cc: Andrew Morton , "Paul E . McKenney" , "Theodore Y . Ts'o" , Matthew Wilcox , Joel Fernandes , RCU , Uladzislau Rezki , Oleksiy Avramchenko , Sebastian Andrzej Siewior Subject: [PATCH v2 07/16] rcu/tree: Use static initializer for krc.lock Date: Mon, 25 May 2020 23:47:51 +0200 Message-Id: <20200525214800.93072-8-urezki@gmail.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200525214800.93072-1-urezki@gmail.com> References: <20200525214800.93072-1-urezki@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: rcu-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org From: Sebastian Andrzej Siewior 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) --- 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 c1f4b740cf14..4b1710c1d8f6 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -2868,7 +2868,7 @@ 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 @@ -2888,7 +2888,9 @@ 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) @@ -2908,8 +2910,7 @@ 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; } @@ -2917,8 +2918,7 @@ 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); } @@ -4141,7 +4141,6 @@ 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; -- 2.20.1