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xen/evtchn: track enabled state for each port

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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>
This commit is contained in:
Jeremy Fitzhardinge 2009-09-18 16:31:22 -07:00
parent 74fca6a428
commit e3cc067b0a
1 changed files with 56 additions and 15 deletions
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71
drivers/xen/evtchn.c
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@ -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);