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Commit 3de88d62 authored by Ross Lagerwall's avatar Ross Lagerwall Committed by David Vrabel
Browse files

xen/events/fifo: Consume unprocessed events when a CPU dies 



When a CPU is offlined, there may be unprocessed events on a port for
that CPU.  If the port is subsequently reused on a different CPU, it
could be in an unexpected state with the link bit set, resulting in
interrupts being missed. Fix this by consuming any unprocessed events
for a particular CPU when that CPU dies.

Signed-off-by: default avatarRoss Lagerwall <ross.lagerwall@citrix.com>
Cc: <stable@vger.kernel.org> # 3.14+
Signed-off-by: default avatarDavid Vrabel <david.vrabel@citrix.com>
parent 86200154

drivers/xen/events/events_fifo.c

+18 −5
Original line number Diff line number Diff line
@@ -281,7 +281,8 @@ static void handle_irq_for_port(unsigned port) 


static void consume_one_event(unsigned cpu,

			      struct evtchn_fifo_control_block *control_block,

			      unsigned priority, unsigned long *ready)

			      unsigned priority, unsigned long *ready,

			      bool drop)

{

	struct evtchn_fifo_queue *q = &per_cpu(cpu_queue, cpu);

	uint32_t head;
@@ -313,13 +314,17 @@ static void consume_one_event(unsigned cpu, 
	if (head == 0)

		clear_bit(priority, ready);



	if (evtchn_fifo_is_pending(port) && !evtchn_fifo_is_masked(port))

	if (evtchn_fifo_is_pending(port) && !evtchn_fifo_is_masked(port)) {

		if (unlikely(drop))

			pr_warn("Dropping pending event for port %u\n", port);

		else

			handle_irq_for_port(port);

	}



	q->head[priority] = head;

}



static void evtchn_fifo_handle_events(unsigned cpu)

static void __evtchn_fifo_handle_events(unsigned cpu, bool drop)

{

	struct evtchn_fifo_control_block *control_block;

	unsigned long ready;
@@ -331,11 +336,16 @@ static void evtchn_fifo_handle_events(unsigned cpu) 


	while (ready) {

		q = find_first_bit(&ready, EVTCHN_FIFO_MAX_QUEUES);

		consume_one_event(cpu, control_block, q, &ready);

		consume_one_event(cpu, control_block, q, &ready, drop);

		ready |= xchg(&control_block->ready, 0);

	}

}



static void evtchn_fifo_handle_events(unsigned cpu)

{

	__evtchn_fifo_handle_events(cpu, false);

}



static void evtchn_fifo_resume(void)

{

	unsigned cpu;
@@ -420,6 +430,9 @@ static int evtchn_fifo_cpu_notification(struct notifier_block *self, 
		if (!per_cpu(cpu_control_block, cpu))

			ret = evtchn_fifo_alloc_control_block(cpu);

		break;

	case CPU_DEAD:

		__evtchn_fifo_handle_events(cpu, true);

		break;

	default:

		break;

	}