diff options
Diffstat (limited to 'drivers/xen/events/events_base.c')
| -rw-r--r-- | drivers/xen/events/events_base.c | 41 |
1 files changed, 36 insertions, 5 deletions
diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c index 6f02c18fa65c..407741ece084 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/spinlock.h> #ifdef CONFIG_X86 #include <asm/desc.h> @@ -71,6 +72,23 @@ 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 + */ + static LIST_HEAD(xen_irq_list_head); /* IRQ <-> VIRQ mapping. */ @@ -105,7 +123,7 @@ static void clear_evtchn_to_irq_row(unsigned row) unsigned col; for (col = 0; col < EVTCHN_PER_ROW; col++) - evtchn_to_irq[row][col] = -1; + WRITE_ONCE(evtchn_to_irq[row][col], -1); } static void clear_evtchn_to_irq_all(void) @@ -142,7 +160,7 @@ static int set_evtchn_to_irq(evtchn_port_t evtchn, unsigned int irq) clear_evtchn_to_irq_row(row); } - evtchn_to_irq[row][col] = irq; + WRITE_ONCE(evtchn_to_irq[row][col], irq); return 0; } @@ -152,7 +170,7 @@ int get_evtchn_to_irq(evtchn_port_t evtchn) return -1; if (evtchn_to_irq[EVTCHN_ROW(evtchn)] == NULL) return -1; - return evtchn_to_irq[EVTCHN_ROW(evtchn)][EVTCHN_COL(evtchn)]; + return READ_ONCE(evtchn_to_irq[EVTCHN_ROW(evtchn)][EVTCHN_COL(evtchn)]); } /* Get info for IRQ */ @@ -261,10 +279,14 @@ static void xen_irq_info_cleanup(struct irq_info *info) */ evtchn_port_t evtchn_from_irq(unsigned irq) { - if (WARN(irq >= nr_irqs, "Invalid irq %d!\n", irq)) + const struct irq_info *info = NULL; + + if (likely(irq < nr_irqs)) + info = info_for_irq(irq); + if (!info) return 0; - return info_for_irq(irq)->evtchn; + return info->evtchn; } unsigned int irq_from_evtchn(evtchn_port_t evtchn) @@ -440,16 +462,21 @@ 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); + 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. */ @@ -1233,6 +1260,8 @@ static void __xen_evtchn_do_upcall(void) struct vcpu_info *vcpu_info = __this_cpu_read(xen_vcpu); int cpu = smp_processor_id(); + read_lock(&evtchn_rwlock); + do { vcpu_info->evtchn_upcall_pending = 0; @@ -1243,6 +1272,8 @@ static void __xen_evtchn_do_upcall(void) virt_rmb(); /* Hypervisor can set upcall pending. */ } while (vcpu_info->evtchn_upcall_pending); + + read_unlock(&evtchn_rwlock); } void xen_evtchn_do_upcall(struct pt_regs *regs) |