From e3cc067b0a79d3a3672bfe7cfba12f2e8ae56039 Mon Sep 17 00:00:00 2001 From: Jeremy Fitzhardinge Date: Fri, 18 Sep 2009 16:31:22 -0700 Subject: 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 --- drivers/xen/evtchn.c | 71 +++++++++++++++++++++++++++++++++++++++++----------- 1 file changed, 56 insertions(+), 15 deletions(-) (limited to 'drivers/xen') diff --git a/drivers/xen/evtchn.c b/drivers/xen/evtchn.c index af031950f9b1..4356a9a030df 100644 --- a/drivers/xen/evtchn.c +++ b/drivers/xen/evtchn.c @@ -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); -- cgit