Merge branch 'rcu/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-2.6-rcu (df8d6fe9) · Commits · EulixOS / Software / Kernel

kernel/rcutree.c

+25 −1

Original line number	Diff line number	Diff line
		@@ -84,9 +84,32 @@ DEFINE_PER_CPU(struct rcu_data, rcu_bh_data);

		static struct rcu_state *rcu_state;

		/*
		* The rcu_scheduler_active variable transitions from zero to one just
		* before the first task is spawned. So when this variable is zero, RCU
		* can assume that there is but one task, allowing RCU to (for example)
		* optimized synchronize_sched() to a simple barrier(). When this variable
		* is one, RCU must actually do all the hard work required to detect real
		* grace periods. This variable is also used to suppress boot-time false
		* positives from lockdep-RCU error checking.
		*/
		int rcu_scheduler_active __read_mostly;
		EXPORT_SYMBOL_GPL(rcu_scheduler_active);

		/*
		* The rcu_scheduler_fully_active variable transitions from zero to one
		* during the early_initcall() processing, which is after the scheduler
		* is capable of creating new tasks. So RCU processing (for example,
		* creating tasks for RCU priority boosting) must be delayed until after
		* rcu_scheduler_fully_active transitions from zero to one. We also
		* currently delay invocation of any RCU callbacks until after this point.
		*
		* It might later prove better for people registering RCU callbacks during
		* early boot to take responsibility for these callbacks, but one step at
		* a time.
		*/
		static int rcu_scheduler_fully_active __read_mostly;

		#ifdef CONFIG_RCU_BOOST

		/*
		@@ -98,7 +121,6 @@ DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_status);
		DEFINE_PER_CPU(int, rcu_cpu_kthread_cpu);
		DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_loops);
		DEFINE_PER_CPU(char, rcu_cpu_has_work);
		static char rcu_kthreads_spawnable;

		#endif /* #ifdef CONFIG_RCU_BOOST */

		@@ -1467,6 +1489,8 @@ static void rcu_process_callbacks(struct softirq_action *unused)
		*/
		static void invoke_rcu_callbacks(struct rcu_state rsp, struct rcu_data rdp)
		{
		if (unlikely(!ACCESS_ONCE(rcu_scheduler_fully_active)))
		return;
		if (likely(!rsp->boost)) {
		rcu_do_batch(rsp, rdp);
		return;

kernel/rcutree_plugin.h

+11 −4

Original line number	Diff line number	Diff line
		@@ -1532,7 +1532,7 @@ static int __cpuinit rcu_spawn_one_cpu_kthread(int cpu)
		struct sched_param sp;
		struct task_struct *t;

		if (!rcu_kthreads_spawnable \|\|
		if (!rcu_scheduler_fully_active \|\|
		per_cpu(rcu_cpu_kthread_task, cpu) != NULL)
		return 0;
		t = kthread_create(rcu_cpu_kthread, (void *)(long)cpu, "rcuc%d", cpu);
		@@ -1639,7 +1639,7 @@ static int __cpuinit rcu_spawn_one_node_kthread(struct rcu_state *rsp,
		struct sched_param sp;
		struct task_struct *t;

		if (!rcu_kthreads_spawnable \|\|
		if (!rcu_scheduler_fully_active \|\|
		rnp->qsmaskinit == 0)
		return 0;
		if (rnp->node_kthread_task == NULL) {
		@@ -1665,7 +1665,7 @@ static int __init rcu_spawn_kthreads(void)
		int cpu;
		struct rcu_node *rnp;

		rcu_kthreads_spawnable = 1;
		rcu_scheduler_fully_active = 1;
		for_each_possible_cpu(cpu) {
		per_cpu(rcu_cpu_has_work, cpu) = 0;
		if (cpu_online(cpu))
		@@ -1687,7 +1687,7 @@ static void __cpuinit rcu_prepare_kthreads(int cpu)
		struct rcu_node *rnp = rdp->mynode;

		/* Fire up the incoming CPU's kthread and leaf rcu_node kthread. */
		if (rcu_kthreads_spawnable) {
		if (rcu_scheduler_fully_active) {
		(void)rcu_spawn_one_cpu_kthread(cpu);
		if (rnp->node_kthread_task == NULL)
		(void)rcu_spawn_one_node_kthread(rcu_state, rnp);
		@@ -1726,6 +1726,13 @@ static void rcu_cpu_kthread_setrt(int cpu, int to_rt)
		{
		}

		static int __init rcu_scheduler_really_started(void)
		{
		rcu_scheduler_fully_active = 1;
		return 0;
		}
		early_initcall(rcu_scheduler_really_started);

		static void __cpuinit rcu_prepare_kthreads(int cpu)
		{
		}