diff options
| -rw-r--r-- | drivers/xen/events/events_base.c | 87 |
1 files changed, 46 insertions, 41 deletions
diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c index c443f04aaad7..80b46de14f41 100644 --- a/drivers/xen/events/events_base.c +++ b/drivers/xen/events/events_base.c @@ -33,6 +33,7 @@ #include <linux/slab.h> #include <linux/irqnr.h> #include <linux/pci.h> +#include <linux/rcupdate.h> #include <linux/spinlock.h> #include <linux/cpuhotplug.h> #include <linux/atomic.h> @@ -96,6 +97,7 @@ enum xen_irq_type { struct irq_info { struct list_head list; struct list_head eoi_list; + struct rcu_work rwork; short refcnt; u8 spurious_cnt; u8 is_accounted; @@ -146,22 +148,12 @@ const struct evtchn_ops *evtchn_ops; static DEFINE_MUTEX(irq_mapping_update_lock); /* - * Lock protecting event handling loop against removing event channels. - * Adding of event channels is no issue as the associated IRQ becomes active - * only after everything is setup (before request_[threaded_]irq() the handler - * can't be entered for an event, as the event channel will be unmasked only - * then). - */ -static DEFINE_RWLOCK(evtchn_rwlock); - -/* * Lock hierarchy: * * irq_mapping_update_lock - * evtchn_rwlock - * IRQ-desc lock - * percpu eoi_list_lock - * irq_info->lock + * IRQ-desc lock + * percpu eoi_list_lock + * irq_info->lock */ static LIST_HEAD(xen_irq_list_head); @@ -305,6 +297,22 @@ static void channels_on_cpu_inc(struct irq_info *info) info->is_accounted = 1; } +static void delayed_free_irq(struct work_struct *work) +{ + struct irq_info *info = container_of(to_rcu_work(work), struct irq_info, + rwork); + unsigned int irq = info->irq; + + /* Remove the info pointer only now, with no potential users left. */ + set_info_for_irq(irq, NULL); + + kfree(info); + + /* Legacy IRQ descriptors are managed by the arch. */ + if (irq >= nr_legacy_irqs()) + irq_free_desc(irq); +} + /* Constructors for packed IRQ information. */ static int xen_irq_info_common_setup(struct irq_info *info, unsigned irq, @@ -667,33 +675,36 @@ static void xen_irq_lateeoi_worker(struct work_struct *work) eoi = container_of(to_delayed_work(work), struct lateeoi_work, delayed); - read_lock_irqsave(&evtchn_rwlock, flags); + rcu_read_lock(); while (true) { - spin_lock(&eoi->eoi_list_lock); + spin_lock_irqsave(&eoi->eoi_list_lock, flags); info = list_first_entry_or_null(&eoi->eoi_list, struct irq_info, eoi_list); - if (info == NULL || now < info->eoi_time) { - spin_unlock(&eoi->eoi_list_lock); + if (info == NULL) + break; + + if (now < info->eoi_time) { + mod_delayed_work_on(info->eoi_cpu, system_wq, + &eoi->delayed, + info->eoi_time - now); break; } list_del_init(&info->eoi_list); - spin_unlock(&eoi->eoi_list_lock); + spin_unlock_irqrestore(&eoi->eoi_list_lock, flags); info->eoi_time = 0; xen_irq_lateeoi_locked(info, false); } - if (info) - mod_delayed_work_on(info->eoi_cpu, system_wq, - &eoi->delayed, info->eoi_time - now); + spin_unlock_irqrestore(&eoi->eoi_list_lock, flags); - read_unlock_irqrestore(&evtchn_rwlock, flags); + rcu_read_unlock(); } static void xen_cpu_init_eoi(unsigned int cpu) @@ -708,16 +719,15 @@ static void xen_cpu_init_eoi(unsigned int cpu) void xen_irq_lateeoi(unsigned int irq, unsigned int eoi_flags) { struct irq_info *info; - unsigned long flags; - read_lock_irqsave(&evtchn_rwlock, flags); + rcu_read_lock(); info = info_for_irq(irq); if (info) xen_irq_lateeoi_locked(info, eoi_flags & XEN_EOI_FLAG_SPURIOUS); - read_unlock_irqrestore(&evtchn_rwlock, flags); + rcu_read_unlock(); } EXPORT_SYMBOL_GPL(xen_irq_lateeoi); @@ -731,6 +741,7 @@ static void xen_irq_init(unsigned irq) info->type = IRQT_UNBOUND; info->refcnt = -1; + INIT_RCU_WORK(&info->rwork, delayed_free_irq); set_info_for_irq(irq, info); /* @@ -788,31 +799,18 @@ static int __must_check xen_allocate_irq_gsi(unsigned gsi) static void xen_free_irq(unsigned irq) { struct irq_info *info = info_for_irq(irq); - unsigned long flags; if (WARN_ON(!info)) return; - write_lock_irqsave(&evtchn_rwlock, flags); - if (!list_empty(&info->eoi_list)) lateeoi_list_del(info); list_del(&info->list); - set_info_for_irq(irq, NULL); - WARN_ON(info->refcnt > 0); - write_unlock_irqrestore(&evtchn_rwlock, flags); - - kfree(info); - - /* Legacy IRQ descriptors are managed by the arch. */ - if (irq < nr_legacy_irqs()) - return; - - irq_free_desc(irq); + queue_rcu_work(system_wq, &info->rwork); } static void xen_evtchn_close(evtchn_port_t port) @@ -1716,7 +1714,14 @@ static void __xen_evtchn_do_upcall(void) int cpu = smp_processor_id(); struct evtchn_loop_ctrl ctrl = { 0 }; - read_lock(&evtchn_rwlock); + /* + * When closing an event channel the associated IRQ must not be freed + * until all cpus have left the event handling loop. This is ensured + * by taking the rcu_read_lock() while handling events, as freeing of + * the IRQ is handled via queue_rcu_work() _after_ closing the event + * channel. + */ + rcu_read_lock(); do { vcpu_info->evtchn_upcall_pending = 0; @@ -1729,7 +1734,7 @@ static void __xen_evtchn_do_upcall(void) } while (vcpu_info->evtchn_upcall_pending); - read_unlock(&evtchn_rwlock); + rcu_read_unlock(); /* * Increment irq_epoch only now to defer EOIs only for |