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Commit 27d50c7e authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

rcu: Make CPU_DYING_IDLE an explicit call 



Make the RCU CPU_DYING_IDLE callback an explicit function call, so it gets
invoked at the proper place.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: Rik van Riel <riel@redhat.com>
Cc: Rafael Wysocki <rafael.j.wysocki@intel.com>
Cc: "Srivatsa S. Bhat" <srivatsa@mit.edu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Turner <pjt@google.com>
Link: http://lkml.kernel.org/r/20160226182341.870167933@linutronix.de


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent e69aab13

include/linux/cpu.h

+1 −3
Original line number Diff line number Diff line
@@ -101,9 +101,7 @@ enum { 
					* Called on the new cpu, just before

					* enabling interrupts. Must not sleep,

					* must not fail */

#define CPU_DYING_IDLE		0x000B /* CPU (unsigned)v dying, reached

					* idle loop. */

#define CPU_BROKEN		0x000C /* CPU (unsigned)v did not die properly,

#define CPU_BROKEN		0x000B /* CPU (unsigned)v did not die properly,

					* perhaps due to preemption. */



/* Used for CPU hotplug events occurring while tasks are frozen due to a suspend

include/linux/notifier.h

+2 −0
Original line number Diff line number Diff line
@@ -47,6 +47,8 @@ 
 * runtime initialization.

 */



struct notifier_block;



typedef	int (*notifier_fn_t)(struct notifier_block *nb,

			unsigned long action, void *data);

include/linux/rcupdate.h

+1 −3
Original line number Diff line number Diff line
@@ -332,9 +332,7 @@ void rcu_init(void); 
void rcu_sched_qs(void);

void rcu_bh_qs(void);

void rcu_check_callbacks(int user);

struct notifier_block;

int rcu_cpu_notify(struct notifier_block *self,

		   unsigned long action, void *hcpu);

void rcu_report_dead(unsigned int cpu);



#ifndef CONFIG_TINY_RCU

void rcu_end_inkernel_boot(void);

kernel/cpu.c

+1 −0
Original line number Diff line number Diff line
@@ -762,6 +762,7 @@ void cpuhp_report_idle_dead(void) 
	BUG_ON(st->state != CPUHP_AP_OFFLINE);

	st->state = CPUHP_AP_IDLE_DEAD;

	complete(&st->done);

	rcu_report_dead(smp_processor_id());

}



#else

kernel/rcu/tree.c

+37 −33
Original line number Diff line number Diff line
@@ -2606,28 +2606,6 @@ static void rcu_cleanup_dead_rnp(struct rcu_node *rnp_leaf) 
	}

}



/*

 * The CPU is exiting the idle loop into the arch_cpu_idle_dead()

 * function.  We now remove it from the rcu_node tree's ->qsmaskinit

 * bit masks.

 */

static void rcu_cleanup_dying_idle_cpu(int cpu, struct rcu_state *rsp)

{

	unsigned long flags;

	unsigned long mask;

	struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);

	struct rcu_node *rnp = rdp->mynode;  /* Outgoing CPU's rdp & rnp. */



	if (!IS_ENABLED(CONFIG_HOTPLUG_CPU))

		return;



	/* Remove outgoing CPU from mask in the leaf rcu_node structure. */

	mask = rdp->grpmask;

	raw_spin_lock_irqsave_rcu_node(rnp, flags); /* Enforce GP memory-order guarantee. */

	rnp->qsmaskinitnext &= ~mask;

	raw_spin_unlock_irqrestore(&rnp->lock, flags);

}



/*

 * The CPU has been completely removed, and some other CPU is reporting

 * this fact from process context.  Do the remainder of the cleanup,
@@ -4247,6 +4225,43 @@ static void rcu_prepare_cpu(int cpu) 
		rcu_init_percpu_data(cpu, rsp);

}



#ifdef CONFIG_HOTPLUG_CPU

/*

 * The CPU is exiting the idle loop into the arch_cpu_idle_dead()

 * function.  We now remove it from the rcu_node tree's ->qsmaskinit

 * bit masks.

 */

static void rcu_cleanup_dying_idle_cpu(int cpu, struct rcu_state *rsp)

{

	unsigned long flags;

	unsigned long mask;

	struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);

	struct rcu_node *rnp = rdp->mynode;  /* Outgoing CPU's rdp & rnp. */



	if (!IS_ENABLED(CONFIG_HOTPLUG_CPU))

		return;



	/* Remove outgoing CPU from mask in the leaf rcu_node structure. */

	mask = rdp->grpmask;

	raw_spin_lock_irqsave_rcu_node(rnp, flags); /* Enforce GP memory-order guarantee. */

	rnp->qsmaskinitnext &= ~mask;

	raw_spin_unlock_irqrestore(&rnp->lock, flags);

}



void rcu_report_dead(unsigned int cpu)

{

	struct rcu_state *rsp;



	/* QS for any half-done expedited RCU-sched GP. */

	preempt_disable();

	rcu_report_exp_rdp(&rcu_sched_state,

			   this_cpu_ptr(rcu_sched_state.rda), true);

	preempt_enable();

	for_each_rcu_flavor(rsp)

		rcu_cleanup_dying_idle_cpu(cpu, rsp);

}

#endif



/*

 * Handle CPU online/offline notification events.

 */
@@ -4278,17 +4293,6 @@ int rcu_cpu_notify(struct notifier_block *self, 
		for_each_rcu_flavor(rsp)

			rcu_cleanup_dying_cpu(rsp);

		break;

	case CPU_DYING_IDLE:

		/* QS for any half-done expedited RCU-sched GP. */

		preempt_disable();

		rcu_report_exp_rdp(&rcu_sched_state,

				   this_cpu_ptr(rcu_sched_state.rda), true);

		preempt_enable();



		for_each_rcu_flavor(rsp) {

			rcu_cleanup_dying_idle_cpu(cpu, rsp);

		}

		break;

	case CPU_DEAD:

	case CPU_DEAD_FROZEN:

	case CPU_UP_CANCELED: