diff options
| -rw-r--r-- | drivers/xen/evtchn.c | 37 |
1 files changed, 25 insertions, 12 deletions
diff --git a/drivers/xen/evtchn.c b/drivers/xen/evtchn.c index 517b9ee..af03195 100644 --- a/drivers/xen/evtchn.c +++ b/drivers/xen/evtchn.c @@ -54,6 +54,8 @@ #include <asm/xen/hypervisor.h> struct per_user_data { + struct mutex bind_mutex; /* serialize bind/unbind operations */ + /* Notification ring, accessed via /dev/xen/evtchn. */ #define EVTCHN_RING_SIZE (PAGE_SIZE / sizeof(evtchn_port_t)) #define EVTCHN_RING_MASK(_i) ((_i)&(EVTCHN_RING_SIZE-1)) @@ -69,7 +71,7 @@ struct per_user_data { /* Who's bound to each port? */ static struct per_user_data *port_user[NR_EVENT_CHANNELS]; -static DEFINE_SPINLOCK(port_user_lock); +static DEFINE_SPINLOCK(port_user_lock); /* protects port_user[] and ring_prod */ irqreturn_t evtchn_interrupt(int irq, void *data) { @@ -210,22 +212,24 @@ static ssize_t evtchn_write(struct file *file, const char __user *buf, static int evtchn_bind_to_user(struct per_user_data *u, int port) { - int irq; int rc = 0; - spin_lock_irq(&port_user_lock); - + /* + * Ports are never reused, so every caller should pass in a + * unique port. + * + * (Locking not necessary because we haven't registered the + * interrupt handler yet, and our caller has already + * serialized bind operations.) + */ BUG_ON(port_user[port] != NULL); - - irq = bind_evtchn_to_irqhandler(port, evtchn_interrupt, IRQF_DISABLED, - u->name, (void *)(unsigned long)port); - if (rc < 0) - goto fail; - port_user[port] = u; -fail: - spin_unlock_irq(&port_user_lock); + rc = bind_evtchn_to_irqhandler(port, evtchn_interrupt, IRQF_DISABLED, + u->name, (void *)(unsigned long)port); + if (rc >= 0) + rc = 0; + return rc; } @@ -234,6 +238,10 @@ static void evtchn_unbind_from_user(struct per_user_data *u, int port) int irq = irq_from_evtchn(port); unbind_from_irqhandler(irq, (void *)(unsigned long)port); + + /* make sure we unbind the irq handler before clearing the port */ + barrier(); + port_user[port] = NULL; } @@ -244,6 +252,9 @@ static long evtchn_ioctl(struct file *file, struct per_user_data *u = file->private_data; void __user *uarg = (void __user *) arg; + /* Prevent bind from racing with unbind */ + mutex_lock(&u->bind_mutex); + switch (cmd) { case IOCTL_EVTCHN_BIND_VIRQ: { struct ioctl_evtchn_bind_virq bind; @@ -368,6 +379,7 @@ static long evtchn_ioctl(struct file *file, rc = -ENOSYS; break; } + mutex_unlock(&u->bind_mutex); return rc; } @@ -414,6 +426,7 @@ static int evtchn_open(struct inode *inode, struct file *filp) return -ENOMEM; } + mutex_init(&u->bind_mutex); mutex_init(&u->ring_cons_mutex); filp->private_data = u; |
