Merge branch 'xen/dev-evtchn' into upstream/evtchn

[pandora-kernel.git] / drivers / xen / evtchn.c

diff --git a/drivers/xen/evtchn.c b/drivers/xen/evtchn.c
index fec6ba3..ef11daf 100644 (file)
--- a/drivers/xen/evtchn.c
+++ b/drivers/xen/evtchn.c
@@ -69,20 +69,51 @@ struct per_user_data {
        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;
 static DEFINE_SPINLOCK(port_user_lock); /* protects port_user[] and ring_prod */
 
-irqreturn_t evtchn_interrupt(int irq, void *data)
+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;
+}
+
+static irqreturn_t evtchn_interrupt(int irq, void *data)
 {
        unsigned int port = (unsigned long)data;
        struct per_user_data *u;
 
        spin_lock(&port_user_lock);
 
-       u = port_user[port];
+       u = get_port_user(port);
+
+       WARN(!get_port_enabled(port),
+            "Interrupt for port %d, but apparently not enabled; per-user %p\n",
+            port, u);
 
        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;
@@ -92,9 +123,8 @@ irqreturn_t evtchn_interrupt(int irq, void *data)
                        kill_fasync(&u->evtchn_async_queue,
                                    SIGIO, POLL_IN);
                }
-       } else {
+       } else
                u->ring_overflow = 1;
-       }
 
        spin_unlock(&port_user_lock);
 
@@ -198,9 +228,18 @@ static ssize_t evtchn_write(struct file *file, const char __user *buf,
                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 +261,9 @@ static int evtchn_bind_to_user(struct per_user_data *u, int port)
         * 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);
+       set_port_enabled(port, true); /* start enabled */
 
        rc = bind_evtchn_to_irqhandler(port, evtchn_interrupt, IRQF_DISABLED,
                                       u->name, (void *)(unsigned long)port);
@@ -239,10 +279,7 @@ static void evtchn_unbind_from_user(struct per_user_data *u, int 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;
+       set_port_user(port, NULL);
 }
 
 static long evtchn_ioctl(struct file *file,
@@ -333,15 +370,17 @@ static long evtchn_ioctl(struct file *file,
                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;
                }
 
-               evtchn_unbind_from_user(u, unbind.port);
+               disable_irq(irq_from_evtchn(unbind.port));
 
                spin_unlock_irq(&port_user_lock);
 
+               evtchn_unbind_from_user(u, unbind.port);
+
                rc = 0;
                break;
        }
@@ -355,7 +394,7 @@ static long evtchn_ioctl(struct file *file,
 
                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);
@@ -431,7 +470,7 @@ static int evtchn_open(struct inode *inode, struct file *filp)
 
        filp->private_data = u;
 
-       return 0;
+       return nonseekable_open(inode, filp);;
 }
 
 static int evtchn_release(struct inode *inode, struct file *filp)
@@ -444,14 +483,21 @@ static int evtchn_release(struct inode *inode, struct file *filp)
        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);
+               disable_irq(irq_from_evtchn(i));
        }
 
        spin_unlock_irq(&port_user_lock);
 
+       for (i = 0; i < NR_EVENT_CHANNELS; i++) {
+               if (get_port_user(i) != u)
+                       continue;
+
+               evtchn_unbind_from_user(get_port_user(i), i);
+       }
+
        kfree(u->name);
        kfree(u);
 
@@ -467,12 +513,12 @@ static const struct file_operations evtchn_fops = {
        .fasync  = evtchn_fasync,
        .open    = evtchn_open,
        .release = evtchn_release,
-       .llseek = noop_llseek,
+       .llseek  = no_llseek,
 };
 
 static struct miscdevice evtchn_miscdev = {
        .minor        = MISC_DYNAMIC_MINOR,
-       .name         = "evtchn",
+       .name         = "xen/evtchn",
        .fops         = &evtchn_fops,
 };
 static int __init evtchn_init(void)
@@ -482,8 +528,11 @@ static int __init evtchn_init(void)
        if (!xen_domain())
                return -ENODEV;
 
+       port_user = kcalloc(NR_EVENT_CHANNELS, sizeof(*port_user), GFP_KERNEL);
+       if (port_user == NULL)
+               return -ENOMEM;
+
        spin_lock_init(&port_user_lock);
-       memset(port_user, 0, sizeof(port_user));
 
        /* Create '/dev/misc/evtchn'. */
        err = misc_register(&evtchn_miscdev);
@@ -499,6 +548,9 @@ static int __init evtchn_init(void)
 
 static void __exit evtchn_cleanup(void)
 {
+       kfree(port_user);
+       port_user = NULL;
+
        misc_deregister(&evtchn_miscdev);
 }