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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: Ross Lagerwall <ross.lagerwall@citrix.com>
Cc: <stable@vger.kernel.org> # 3.14+
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
This commit is contained in:
Ross Lagerwall 2015-06-19 16:15:57 +01:00 committed by David Vrabel
parent 8620015499
commit 3de88d622f
1 changed files with 18 additions and 5 deletions
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23
drivers/xen/events/events_fifo.c
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@ -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))
handle_irq_for_port(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;
}