diff options
Diffstat (limited to 'drivers/xen/evtchn.c')
| -rw-r--r-- | drivers/xen/evtchn.c | 123 |
1 files changed, 107 insertions, 16 deletions
diff --git a/drivers/xen/evtchn.c b/drivers/xen/evtchn.c index 00f40f051d95..38272ad24551 100644 --- a/drivers/xen/evtchn.c +++ b/drivers/xen/evtchn.c @@ -49,6 +49,8 @@ #include <linux/init.h> #include <linux/mutex.h> #include <linux/cpu.h> +#include <linux/mm.h> +#include <linux/vmalloc.h> #include <xen/xen.h> #include <xen/events.h> @@ -58,10 +60,10 @@ struct per_user_data { struct mutex bind_mutex; /* serialize bind/unbind operations */ struct rb_root evtchns; + unsigned int nr_evtchns; /* Notification ring, accessed via /dev/xen/evtchn. */ -#define EVTCHN_RING_SIZE (PAGE_SIZE / sizeof(evtchn_port_t)) -#define EVTCHN_RING_MASK(_i) ((_i)&(EVTCHN_RING_SIZE-1)) + unsigned int ring_size; evtchn_port_t *ring; unsigned int ring_cons, ring_prod, ring_overflow; struct mutex ring_cons_mutex; /* protect against concurrent readers */ @@ -80,10 +82,41 @@ struct user_evtchn { bool enabled; }; +static evtchn_port_t *evtchn_alloc_ring(unsigned int size) +{ + evtchn_port_t *ring; + size_t s = size * sizeof(*ring); + + ring = kmalloc(s, GFP_KERNEL); + if (!ring) + ring = vmalloc(s); + + return ring; +} + +static void evtchn_free_ring(evtchn_port_t *ring) +{ + kvfree(ring); +} + +static unsigned int evtchn_ring_offset(struct per_user_data *u, + unsigned int idx) +{ + return idx & (u->ring_size - 1); +} + +static evtchn_port_t *evtchn_ring_entry(struct per_user_data *u, + unsigned int idx) +{ + return u->ring + evtchn_ring_offset(u, idx); +} + static int add_evtchn(struct per_user_data *u, struct user_evtchn *evtchn) { struct rb_node **new = &(u->evtchns.rb_node), *parent = NULL; + u->nr_evtchns++; + while (*new) { struct user_evtchn *this; @@ -107,6 +140,7 @@ static int add_evtchn(struct per_user_data *u, struct user_evtchn *evtchn) static void del_evtchn(struct per_user_data *u, struct user_evtchn *evtchn) { + u->nr_evtchns--; rb_erase(&evtchn->node, &u->evtchns); kfree(evtchn); } @@ -144,8 +178,8 @@ static irqreturn_t evtchn_interrupt(int irq, void *data) spin_lock(&u->ring_prod_lock); - if ((u->ring_prod - u->ring_cons) < EVTCHN_RING_SIZE) { - u->ring[EVTCHN_RING_MASK(u->ring_prod)] = evtchn->port; + if ((u->ring_prod - u->ring_cons) < u->ring_size) { + *evtchn_ring_entry(u, u->ring_prod) = evtchn->port; wmb(); /* Ensure ring contents visible */ if (u->ring_cons == u->ring_prod++) { wake_up_interruptible(&u->evtchn_wait); @@ -200,10 +234,10 @@ static ssize_t evtchn_read(struct file *file, char __user *buf, } /* Byte lengths of two chunks. Chunk split (if any) is at ring wrap. */ - if (((c ^ p) & EVTCHN_RING_SIZE) != 0) { - bytes1 = (EVTCHN_RING_SIZE - EVTCHN_RING_MASK(c)) * + if (((c ^ p) & u->ring_size) != 0) { + bytes1 = (u->ring_size - evtchn_ring_offset(u, c)) * sizeof(evtchn_port_t); - bytes2 = EVTCHN_RING_MASK(p) * sizeof(evtchn_port_t); + bytes2 = evtchn_ring_offset(u, p) * sizeof(evtchn_port_t); } else { bytes1 = (p - c) * sizeof(evtchn_port_t); bytes2 = 0; @@ -219,7 +253,7 @@ static ssize_t evtchn_read(struct file *file, char __user *buf, rc = -EFAULT; rmb(); /* Ensure that we see the port before we copy it. */ - if (copy_to_user(buf, &u->ring[EVTCHN_RING_MASK(c)], bytes1) || + if (copy_to_user(buf, evtchn_ring_entry(u, c), bytes1) || ((bytes2 != 0) && copy_to_user(&buf[bytes1], &u->ring[0], bytes2))) goto unlock_out; @@ -278,6 +312,66 @@ static ssize_t evtchn_write(struct file *file, const char __user *buf, return rc; } +static int evtchn_resize_ring(struct per_user_data *u) +{ + unsigned int new_size; + evtchn_port_t *new_ring, *old_ring; + unsigned int p, c; + + /* + * Ensure the ring is large enough to capture all possible + * events. i.e., one free slot for each bound event. + */ + if (u->nr_evtchns <= u->ring_size) + return 0; + + if (u->ring_size == 0) + new_size = 64; + else + new_size = 2 * u->ring_size; + + new_ring = evtchn_alloc_ring(new_size); + if (!new_ring) + return -ENOMEM; + + old_ring = u->ring; + + /* + * Access to the ring contents is serialized by either the + * prod /or/ cons lock so take both when resizing. + */ + mutex_lock(&u->ring_cons_mutex); + spin_lock_irq(&u->ring_prod_lock); + + /* + * Copy the old ring contents to the new ring. + * + * If the ring contents crosses the end of the current ring, + * it needs to be copied in two chunks. + * + * +---------+ +------------------+ + * |34567 12| -> | 1234567 | + * +-----p-c-+ +------------------+ + */ + p = evtchn_ring_offset(u, u->ring_prod); + c = evtchn_ring_offset(u, u->ring_cons); + if (p < c) { + memcpy(new_ring + c, u->ring + c, (u->ring_size - c) * sizeof(*u->ring)); + memcpy(new_ring + u->ring_size, u->ring, p * sizeof(*u->ring)); + } else + memcpy(new_ring + c, u->ring + c, (p - c) * sizeof(*u->ring)); + + u->ring = new_ring; + u->ring_size = new_size; + + spin_unlock_irq(&u->ring_prod_lock); + mutex_unlock(&u->ring_cons_mutex); + + evtchn_free_ring(old_ring); + + return 0; +} + static int evtchn_bind_to_user(struct per_user_data *u, int port) { struct user_evtchn *evtchn; @@ -305,6 +399,10 @@ static int evtchn_bind_to_user(struct per_user_data *u, int port) if (rc < 0) goto err; + rc = evtchn_resize_ring(u); + if (rc < 0) + goto err; + rc = bind_evtchn_to_irqhandler(port, evtchn_interrupt, 0, u->name, evtchn); if (rc < 0) @@ -503,13 +601,6 @@ static int evtchn_open(struct inode *inode, struct file *filp) init_waitqueue_head(&u->evtchn_wait); - u->ring = (evtchn_port_t *)__get_free_page(GFP_KERNEL); - if (u->ring == NULL) { - kfree(u->name); - kfree(u); - return -ENOMEM; - } - mutex_init(&u->bind_mutex); mutex_init(&u->ring_cons_mutex); spin_lock_init(&u->ring_prod_lock); @@ -532,7 +623,7 @@ static int evtchn_release(struct inode *inode, struct file *filp) evtchn_unbind_from_user(u, evtchn); } - free_page((unsigned long)u->ring); + evtchn_free_ring(u->ring); kfree(u->name); kfree(u); |