Commit 96abb968 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Thomas Gleixner
Browse files

smp/hotplug: Allow external multi-instance rollback 



Currently the rollback of multi-instance states is handled inside
cpuhp_invoke_callback(). The problem is that when we want to allow an
explicit state change for rollback, we need to return from the
function without doing the rollback.

Change cpuhp_invoke_callback() to optionally return the multi-instance
state, such that rollback can be done from a subsequent call.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: bigeasy@linutronix.de
Cc: efault@gmx.de
Cc: rostedt@goodmis.org
Cc: max.byungchul.park@gmail.com
Link: https://lkml.kernel.org/r/20170920170546.720361181@infradead.org
parent fac1c204

kernel/cpu.c

+32 −15
Original line number Diff line number Diff line
@@ -123,13 +123,16 @@ static struct cpuhp_step *cpuhp_get_step(enum cpuhp_state state) 
/**

 * cpuhp_invoke_callback _ Invoke the callbacks for a given state

 * @cpu:	The cpu for which the callback should be invoked

 * @step:	The step in the state machine

 * @state:	The state to do callbacks for

 * @bringup:	True if the bringup callback should be invoked

 * @node:	For multi-instance, do a single entry callback for install/remove

 * @lastp:	For multi-instance rollback, remember how far we got

 *

 * Called from cpu hotplug and from the state register machinery.

 */

static int cpuhp_invoke_callback(unsigned int cpu, enum cpuhp_state state,

				 bool bringup, struct hlist_node *node)

				 bool bringup, struct hlist_node *node,

				 struct hlist_node **lastp)

{

	struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);

	struct cpuhp_step *step = cpuhp_get_step(state);
@@ -138,6 +141,7 @@ static int cpuhp_invoke_callback(unsigned int cpu, enum cpuhp_state state, 
	int ret, cnt;



	if (!step->multi_instance) {

		WARN_ON_ONCE(lastp && *lastp);

		cb = bringup ? step->startup.single : step->teardown.single;

		if (!cb)

			return 0;
@@ -152,6 +156,7 @@ static int cpuhp_invoke_callback(unsigned int cpu, enum cpuhp_state state, 


	/* Single invocation for instance add/remove */

	if (node) {

		WARN_ON_ONCE(lastp && *lastp);

		trace_cpuhp_multi_enter(cpu, st->target, state, cbm, node);

		ret = cbm(cpu, node);

		trace_cpuhp_exit(cpu, st->state, state, ret);
@@ -161,13 +166,23 @@ static int cpuhp_invoke_callback(unsigned int cpu, enum cpuhp_state state, 
	/* State transition. Invoke on all instances */

	cnt = 0;

	hlist_for_each(node, &step->list) {

		if (lastp && node == *lastp)

			break;



		trace_cpuhp_multi_enter(cpu, st->target, state, cbm, node);

		ret = cbm(cpu, node);

		trace_cpuhp_exit(cpu, st->state, state, ret);

		if (ret)

		if (ret) {

			if (!lastp)

				goto err;



			*lastp = node;

			return ret;

		}

		cnt++;

	}

	if (lastp)

		*lastp = NULL;

	return 0;

err:

	/* Rollback the instances if one failed */
@@ -323,7 +338,7 @@ static void undo_cpu_down(unsigned int cpu, struct cpuhp_cpu_state *st) 
		struct cpuhp_step *step = cpuhp_get_step(st->state);



		if (!step->skip_onerr)

			cpuhp_invoke_callback(cpu, st->state, true, NULL);

			cpuhp_invoke_callback(cpu, st->state, true, NULL, NULL);

	}

}
@@ -334,7 +349,7 @@ static int cpuhp_down_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st, 
	int ret = 0;



	for (; st->state > target; st->state--) {

		ret = cpuhp_invoke_callback(cpu, st->state, false, NULL);

		ret = cpuhp_invoke_callback(cpu, st->state, false, NULL, NULL);

		if (ret) {

			st->target = prev_state;

			undo_cpu_down(cpu, st);
@@ -350,7 +365,7 @@ static void undo_cpu_up(unsigned int cpu, struct cpuhp_cpu_state *st) 
		struct cpuhp_step *step = cpuhp_get_step(st->state);



		if (!step->skip_onerr)

			cpuhp_invoke_callback(cpu, st->state, false, NULL);

			cpuhp_invoke_callback(cpu, st->state, false, NULL, NULL);

	}

}
@@ -362,7 +377,7 @@ static int cpuhp_up_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st, 


	while (st->state < target) {

		st->state++;

		ret = cpuhp_invoke_callback(cpu, st->state, true, NULL);

		ret = cpuhp_invoke_callback(cpu, st->state, true, NULL, NULL);

		if (ret) {

			st->target = prev_state;

			undo_cpu_up(cpu, st);
@@ -428,11 +443,13 @@ static void cpuhp_thread_fun(unsigned int cpu) 
		if (st->cb_state < CPUHP_AP_ONLINE) {

			local_irq_disable();

			ret = cpuhp_invoke_callback(cpu, st->cb_state,

						    st->bringup, st->node);

						    st->bringup, st->node,

						    NULL);

			local_irq_enable();

		} else {

			ret = cpuhp_invoke_callback(cpu, st->cb_state,

						    st->bringup, st->node);

						    st->bringup, st->node,

						    NULL);

		}

	} else if (st->rollback) {

		BUG_ON(st->state < CPUHP_AP_ONLINE_IDLE);
@@ -472,7 +489,7 @@ cpuhp_invoke_ap_callback(int cpu, enum cpuhp_state state, bool bringup, 
	 * we invoke the thread function directly.

	 */

	if (!st->thread)

		return cpuhp_invoke_callback(cpu, state, bringup, node);

		return cpuhp_invoke_callback(cpu, state, bringup, node, NULL);



	st->cb_state = state;

	st->single = true;
@@ -595,7 +612,7 @@ static int take_cpu_down(void *_param) 
	st->state--;

	/* Invoke the former CPU_DYING callbacks */

	for (; st->state > target; st->state--)

		cpuhp_invoke_callback(cpu, st->state, false, NULL);

		cpuhp_invoke_callback(cpu, st->state, false, NULL, NULL);



	/* Give up timekeeping duties */

	tick_handover_do_timer();
@@ -776,7 +793,7 @@ void notify_cpu_starting(unsigned int cpu) 
	rcu_cpu_starting(cpu);	/* Enables RCU usage on this CPU. */

	while (st->state < target) {

		st->state++;

		cpuhp_invoke_callback(cpu, st->state, true, NULL);

		cpuhp_invoke_callback(cpu, st->state, true, NULL, NULL);

	}

}
@@ -1307,9 +1324,9 @@ static int cpuhp_issue_call(int cpu, enum cpuhp_state state, bool bringup, 
	if (cpuhp_is_ap_state(state))

		ret = cpuhp_invoke_ap_callback(cpu, state, bringup, node);

	else

		ret = cpuhp_invoke_callback(cpu, state, bringup, node);

		ret = cpuhp_invoke_callback(cpu, state, bringup, node, NULL);

#else

	ret = cpuhp_invoke_callback(cpu, state, bringup, node);

	ret = cpuhp_invoke_callback(cpu, state, bringup, node, NULL);

#endif

	BUG_ON(ret && !bringup);

	return ret;

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