+++ /dev/null
-From fcdf31a7c162de0c93a2bee51df4688ab0a348f8 Mon Sep 17 00:00:00 2001
-From: Ross Lagerwall <ross.lagerwall@citrix.com>
-Date: Fri, 31 Jul 2015 14:30:42 +0100
-Subject: xen/events/fifo: Handle linked events when closing a port
-
-From: Ross Lagerwall <ross.lagerwall@citrix.com>
-
-commit fcdf31a7c162de0c93a2bee51df4688ab0a348f8 upstream.
-
-An event channel bound to a CPU that was offlined may still be linked
-on that CPU's queue. If this event channel is closed and reused,
-subsequent events will be lost because the event channel is never
-unlinked and thus cannot be linked onto the correct queue.
-
-When a channel is closed and the event is still linked into a queue,
-ensure that it is unlinked before completing.
-
-If the CPU to which the event channel bound is online, spin until the
-event is handled by that CPU. If that CPU is offline, it can't handle
-the event, so clear the event queue during the close, dropping the
-events.
-
-This fixes the missing interrupts (and subsequent disk stalls etc.)
-when offlining a CPU.
-
-Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
-Signed-off-by: David Vrabel <david.vrabel@citrix.com>
-Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-
----
- drivers/xen/events/events_base.c | 10 ++++---
- drivers/xen/events/events_fifo.c | 45 +++++++++++++++++++++++++++++++----
- drivers/xen/events/events_internal.h | 7 +++++
- 3 files changed, 53 insertions(+), 9 deletions(-)
-
---- a/drivers/xen/events/events_base.c
-+++ b/drivers/xen/events/events_base.c
-@@ -452,10 +452,12 @@ static void xen_free_irq(unsigned irq)
- irq_free_desc(irq);
- }
-
--static void xen_evtchn_close(unsigned int port)
-+static void xen_evtchn_close(unsigned int port, unsigned int cpu)
- {
- struct evtchn_close close;
-
-+ xen_evtchn_op_close(port, cpu);
-+
- close.port = port;
- if (HYPERVISOR_event_channel_op(EVTCHNOP_close, &close) != 0)
- BUG();
-@@ -544,7 +546,7 @@ out:
-
- err:
- pr_err("irq%d: Failed to set port to irq mapping (%d)\n", irq, rc);
-- xen_evtchn_close(evtchn);
-+ xen_evtchn_close(evtchn, NR_CPUS);
- return 0;
- }
-
-@@ -565,7 +567,7 @@ static void shutdown_pirq(struct irq_dat
- return;
-
- mask_evtchn(evtchn);
-- xen_evtchn_close(evtchn);
-+ xen_evtchn_close(evtchn, cpu_from_evtchn(evtchn));
- xen_irq_info_cleanup(info);
- }
-
-@@ -609,7 +611,7 @@ static void __unbind_from_irq(unsigned i
- if (VALID_EVTCHN(evtchn)) {
- unsigned int cpu = cpu_from_irq(irq);
-
-- xen_evtchn_close(evtchn);
-+ xen_evtchn_close(evtchn, cpu);
-
- switch (type_from_irq(irq)) {
- case IRQT_VIRQ:
---- a/drivers/xen/events/events_fifo.c
-+++ b/drivers/xen/events/events_fifo.c
-@@ -255,6 +255,12 @@ static void evtchn_fifo_unmask(unsigned
- }
- }
-
-+static bool evtchn_fifo_is_linked(unsigned port)
-+{
-+ event_word_t *word = event_word_from_port(port);
-+ return sync_test_bit(EVTCHN_FIFO_BIT(LINKED, word), BM(word));
-+}
-+
- static uint32_t clear_linked(volatile event_word_t *word)
- {
- event_word_t new, old, w;
-@@ -281,7 +287,8 @@ static void handle_irq_for_port(unsigned
-
- 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 +320,15 @@ static void consume_one_event(unsigned c
- 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 (likely(!drop))
-+ 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 +340,16 @@ static void evtchn_fifo_handle_events(un
-
- 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;
-@@ -371,6 +385,26 @@ static void evtchn_fifo_resume(void)
- event_array_pages = 0;
- }
-
-+static void evtchn_fifo_close(unsigned port, unsigned int cpu)
-+{
-+ if (cpu == NR_CPUS)
-+ return;
-+
-+ get_online_cpus();
-+ if (cpu_online(cpu)) {
-+ if (WARN_ON(irqs_disabled()))
-+ goto out;
-+
-+ while (evtchn_fifo_is_linked(port))
-+ cpu_relax();
-+ } else {
-+ __evtchn_fifo_handle_events(cpu, true);
-+ }
-+
-+out:
-+ put_online_cpus();
-+}
-+
- static const struct evtchn_ops evtchn_ops_fifo = {
- .max_channels = evtchn_fifo_max_channels,
- .nr_channels = evtchn_fifo_nr_channels,
-@@ -384,6 +418,7 @@ static const struct evtchn_ops evtchn_op
- .unmask = evtchn_fifo_unmask,
- .handle_events = evtchn_fifo_handle_events,
- .resume = evtchn_fifo_resume,
-+ .close = evtchn_fifo_close,
- };
-
- static int evtchn_fifo_alloc_control_block(unsigned cpu)
---- a/drivers/xen/events/events_internal.h
-+++ b/drivers/xen/events/events_internal.h
-@@ -68,6 +68,7 @@ struct evtchn_ops {
- bool (*test_and_set_mask)(unsigned port);
- void (*mask)(unsigned port);
- void (*unmask)(unsigned port);
-+ void (*close)(unsigned port, unsigned cpu);
-
- void (*handle_events)(unsigned cpu);
- void (*resume)(void);
-@@ -145,6 +146,12 @@ static inline void xen_evtchn_resume(voi
- evtchn_ops->resume();
- }
-
-+static inline void xen_evtchn_op_close(unsigned port, unsigned cpu)
-+{
-+ if (evtchn_ops->close)
-+ return evtchn_ops->close(port, cpu);
-+}
-+
- void xen_evtchn_2l_init(void);
- int xen_evtchn_fifo_init(void);
-
projects / thirdparty / kernel / stable-queue.git / commitdiff
