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Commit e3cc067b authored by Jeremy Fitzhardinge's avatar Jeremy Fitzhardinge
Browse files

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: default avatarJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
parent 74fca6a4

drivers/xen/evtchn.c

+56 −15
Original line number Diff line number Diff line
@@ -69,10 +69,36 @@ 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[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 @@ irqreturn_t evtchn_interrupt(int irq, void *data) 


	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 @@ irqreturn_t evtchn_interrupt(int irq, void *data) 
			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 @@ 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 +263,8 @@ 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);



	rc = bind_evtchn_to_irqhandler(port, evtchn_interrupt, IRQF_DISABLED,

				       u->name, (void *)(unsigned long)port);
@@ -242,7 +283,7 @@ static void evtchn_unbind_from_user(struct per_user_data *u, int 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,
@@ -333,7 +374,7 @@ 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;

		}
@@ -355,7 +396,7 @@ 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);
@@ -444,10 +485,10 @@ 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);

		evtchn_unbind_from_user(get_port_user(i), i);

	}



	spin_unlock_irq(&port_user_lock);