From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965288AbbCPSmw (ORCPT ); Mon, 16 Mar 2015 14:42:52 -0400 Received: from e38.co.us.ibm.com ([32.97.110.159]:60368 "EHLO e38.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965086AbbCPSmf (ORCPT ); Mon, 16 Mar 2015 14:42:35 -0400 From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@kernel.org, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, dvhart@linux.intel.com, fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com, "Paul E. McKenney" Subject: [PATCH v2 tip/core/rcu 9/9] Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE() in update.c Date: Mon, 16 Mar 2015 11:42:24 -0700 Message-Id: <1426531344-24822-9-git-send-email-paulmck@linux.vnet.ibm.com> X-Mailer: git-send-email 1.8.1.5 In-Reply-To: <1426531344-24822-1-git-send-email-paulmck@linux.vnet.ibm.com> References: <20150316184155.GA24290@linux.vnet.ibm.com> <1426531344-24822-1-git-send-email-paulmck@linux.vnet.ibm.com> X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15031618-0029-0000-0000-00000891D606 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Paul E. McKenney" This commit moves kernel/rcu/update.c from the old ACCESS_ONCE() API to the new READ_ONCE() and WRITE_ONCE() APIs. Signed-off-by: Paul E. McKenney --- kernel/rcu/update.c | 30 +++++++++++++++--------------- 1 file changed, 15 insertions(+), 15 deletions(-) diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c index 1f133350da01..afaecb7a799a 100644 --- a/kernel/rcu/update.c +++ b/kernel/rcu/update.c @@ -150,14 +150,14 @@ void __rcu_read_unlock(void) barrier(); /* critical section before exit code. */ t->rcu_read_lock_nesting = INT_MIN; barrier(); /* assign before ->rcu_read_unlock_special load */ - if (unlikely(ACCESS_ONCE(t->rcu_read_unlock_special.s))) + if (unlikely(READ_ONCE(t->rcu_read_unlock_special.s))) rcu_read_unlock_special(t); barrier(); /* ->rcu_read_unlock_special load before assign */ t->rcu_read_lock_nesting = 0; } #ifdef CONFIG_PROVE_LOCKING { - int rrln = ACCESS_ONCE(t->rcu_read_lock_nesting); + int rrln = READ_ONCE(t->rcu_read_lock_nesting); WARN_ON_ONCE(rrln < 0 && rrln > INT_MIN / 2); } @@ -389,17 +389,17 @@ module_param(rcu_cpu_stall_timeout, int, 0644); int rcu_jiffies_till_stall_check(void) { - int till_stall_check = ACCESS_ONCE(rcu_cpu_stall_timeout); + int till_stall_check = READ_ONCE(rcu_cpu_stall_timeout); /* * Limit check must be consistent with the Kconfig limits * for CONFIG_RCU_CPU_STALL_TIMEOUT. */ if (till_stall_check < 3) { - ACCESS_ONCE(rcu_cpu_stall_timeout) = 3; + WRITE_ONCE(rcu_cpu_stall_timeout, 3); till_stall_check = 3; } else if (till_stall_check > 300) { - ACCESS_ONCE(rcu_cpu_stall_timeout) = 300; + WRITE_ONCE(rcu_cpu_stall_timeout, 300); till_stall_check = 300; } return till_stall_check * HZ + RCU_STALL_DELAY_DELTA; @@ -550,12 +550,12 @@ static void check_holdout_task(struct task_struct *t, { int cpu; - if (!ACCESS_ONCE(t->rcu_tasks_holdout) || - t->rcu_tasks_nvcsw != ACCESS_ONCE(t->nvcsw) || - !ACCESS_ONCE(t->on_rq) || + if (!READ_ONCE(t->rcu_tasks_holdout) || + t->rcu_tasks_nvcsw != READ_ONCE(t->nvcsw) || + !READ_ONCE(t->on_rq) || (IS_ENABLED(CONFIG_NO_HZ_FULL) && !is_idle_task(t) && t->rcu_tasks_idle_cpu >= 0)) { - ACCESS_ONCE(t->rcu_tasks_holdout) = false; + WRITE_ONCE(t->rcu_tasks_holdout, false); list_del_init(&t->rcu_tasks_holdout_list); put_task_struct(t); return; @@ -639,11 +639,11 @@ static int __noreturn rcu_tasks_kthread(void *arg) */ rcu_read_lock(); for_each_process_thread(g, t) { - if (t != current && ACCESS_ONCE(t->on_rq) && + if (t != current && READ_ONCE(t->on_rq) && !is_idle_task(t)) { get_task_struct(t); - t->rcu_tasks_nvcsw = ACCESS_ONCE(t->nvcsw); - ACCESS_ONCE(t->rcu_tasks_holdout) = true; + t->rcu_tasks_nvcsw = READ_ONCE(t->nvcsw); + WRITE_ONCE(t->rcu_tasks_holdout, true); list_add(&t->rcu_tasks_holdout_list, &rcu_tasks_holdouts); } @@ -672,7 +672,7 @@ static int __noreturn rcu_tasks_kthread(void *arg) struct task_struct *t1; schedule_timeout_interruptible(HZ); - rtst = ACCESS_ONCE(rcu_task_stall_timeout); + rtst = READ_ONCE(rcu_task_stall_timeout); needreport = rtst > 0 && time_after(jiffies, lastreport + rtst); if (needreport) @@ -728,7 +728,7 @@ static void rcu_spawn_tasks_kthread(void) static struct task_struct *rcu_tasks_kthread_ptr; struct task_struct *t; - if (ACCESS_ONCE(rcu_tasks_kthread_ptr)) { + if (READ_ONCE(rcu_tasks_kthread_ptr)) { smp_mb(); /* Ensure caller sees full kthread. */ return; } @@ -740,7 +740,7 @@ static void rcu_spawn_tasks_kthread(void) t = kthread_run(rcu_tasks_kthread, NULL, "rcu_tasks_kthread"); BUG_ON(IS_ERR(t)); smp_mb(); /* Ensure others see full kthread. */ - ACCESS_ONCE(rcu_tasks_kthread_ptr) = t; + WRITE_ONCE(rcu_tasks_kthread_ptr, t); mutex_unlock(&rcu_tasks_kthread_mutex); } -- 1.8.1.5