#include <linux/string.h>
#include <linux/errno.h>
#include <linux/fs.h>
-#include <linux/errno.h>
#include <linux/miscdevice.h>
#include <linux/major.h>
#include <linux/proc_fs.h>
#include <linux/poll.h>
#include <linux/irq.h>
#include <linux/init.h>
-#include <linux/gfp.h>
#include <linux/mutex.h>
#include <linux/cpu.h>
+
+#include <xen/xen.h>
#include <xen/events.h>
#include <xen/evtchn.h>
#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))
/* 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)
{
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;
}
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;
}
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;
rc = -ENOSYS;
break;
}
+ mutex_unlock(&u->bind_mutex);
return rc;
}
return -ENOMEM;
}
+ mutex_init(&u->bind_mutex);
mutex_init(&u->ring_cons_mutex);
filp->private_data = u;