xen/evtchn: track enabled state for each port
enable/disable_irq() complain if the enables/disables are unbalanced,
so keep track of the state and avoid redundant enables.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
diff --git a/drivers/xen/evtchn.c b/drivers/xen/evtchn.c
index af03195..4356a9a 100644
--- a/drivers/xen/evtchn.c
+++ b/drivers/xen/evtchn.c
@@ -69,10 +69,36 @@
const char *name;
};
-/* Who's bound to each port? */
-static struct per_user_data *port_user[NR_EVENT_CHANNELS];
+/*
+ * Who's bound to each port? This is logically an array of struct
+ * per_user_data *, but we encode the current enabled-state in bit 0.
+ */
+static unsigned long port_user[NR_EVENT_CHANNELS];
static DEFINE_SPINLOCK(port_user_lock); /* protects port_user[] and ring_prod */
+static inline struct per_user_data *get_port_user(unsigned port)
+{
+ return (struct per_user_data *)(port_user[port] & ~1);
+}
+
+static inline void set_port_user(unsigned port, struct per_user_data *u)
+{
+ port_user[port] = (unsigned long)u;
+}
+
+static inline bool get_port_enabled(unsigned port)
+{
+ return port_user[port] & 1;
+}
+
+static inline void set_port_enabled(unsigned port, bool enabled)
+{
+ if (enabled)
+ port_user[port] |= 1;
+ else
+ port_user[port] &= ~1;
+}
+
irqreturn_t evtchn_interrupt(int irq, void *data)
{
unsigned int port = (unsigned long)data;
@@ -80,9 +106,15 @@
spin_lock(&port_user_lock);
- u = port_user[port];
+ u = get_port_user(port);
+
+ if (WARN(!get_port_enabled(port),
+ "Interrupt for port %d, but apparently not enabled; per-user %p\n",
+ port, u))
+ goto out;
disable_irq_nosync(irq);
+ set_port_enabled(port, false);
if ((u->ring_prod - u->ring_cons) < EVTCHN_RING_SIZE) {
u->ring[EVTCHN_RING_MASK(u->ring_prod)] = port;
@@ -92,10 +124,10 @@
kill_fasync(&u->evtchn_async_queue,
SIGIO, POLL_IN);
}
- } else {
+ } else
u->ring_overflow = 1;
- }
+out:
spin_unlock(&port_user_lock);
return IRQ_HANDLED;
@@ -198,9 +230,18 @@
goto out;
spin_lock_irq(&port_user_lock);
- for (i = 0; i < (count/sizeof(evtchn_port_t)); i++)
- if ((kbuf[i] < NR_EVENT_CHANNELS) && (port_user[kbuf[i]] == u))
- enable_irq(irq_from_evtchn(kbuf[i]));
+
+ for (i = 0; i < (count/sizeof(evtchn_port_t)); i++) {
+ unsigned port = kbuf[i];
+
+ if (port < NR_EVENT_CHANNELS &&
+ get_port_user(port) == u &&
+ !get_port_enabled(port)) {
+ set_port_enabled(port, true);
+ enable_irq(irq_from_evtchn(port));
+ }
+ }
+
spin_unlock_irq(&port_user_lock);
rc = count;
@@ -222,8 +263,8 @@
* interrupt handler yet, and our caller has already
* serialized bind operations.)
*/
- BUG_ON(port_user[port] != NULL);
- port_user[port] = u;
+ BUG_ON(get_port_user(port) != NULL);
+ set_port_user(port, u);
rc = bind_evtchn_to_irqhandler(port, evtchn_interrupt, IRQF_DISABLED,
u->name, (void *)(unsigned long)port);
@@ -242,7 +283,7 @@
/* make sure we unbind the irq handler before clearing the port */
barrier();
- port_user[port] = NULL;
+ set_port_user(port, NULL);
}
static long evtchn_ioctl(struct file *file,
@@ -333,7 +374,7 @@
spin_lock_irq(&port_user_lock);
rc = -ENOTCONN;
- if (port_user[unbind.port] != u) {
+ if (get_port_user(unbind.port) != u) {
spin_unlock_irq(&port_user_lock);
break;
}
@@ -355,7 +396,7 @@
if (notify.port >= NR_EVENT_CHANNELS) {
rc = -EINVAL;
- } else if (port_user[notify.port] != u) {
+ } else if (get_port_user(notify.port) != u) {
rc = -ENOTCONN;
} else {
notify_remote_via_evtchn(notify.port);
@@ -444,10 +485,10 @@
free_page((unsigned long)u->ring);
for (i = 0; i < NR_EVENT_CHANNELS; i++) {
- if (port_user[i] != u)
+ if (get_port_user(i) != u)
continue;
- evtchn_unbind_from_user(port_user[i], i);
+ evtchn_unbind_from_user(get_port_user(i), i);
}
spin_unlock_irq(&port_user_lock);
