# HG changeset patch
# User kfraser@xxxxxxxxxxxxxxxxxxxxx
# Date 1175086323 -3600
# Node ID 77b210daefee957faa220e94501ace6bf50e3b97
# Parent 7e6ef2b914aa739c51f15b0700aa54de41b4707d
linux evtchn: Read function in evtchn driver requires locking.
Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>
---
linux-2.6-xen-sparse/drivers/xen/evtchn/evtchn.c | 34 +++++++++++++++--------
1 files changed, 23 insertions(+), 11 deletions(-)
diff -r 7e6ef2b914aa -r 77b210daefee
linux-2.6-xen-sparse/drivers/xen/evtchn/evtchn.c
--- a/linux-2.6-xen-sparse/drivers/xen/evtchn/evtchn.c Wed Mar 28 12:38:13
2007 +0100
+++ b/linux-2.6-xen-sparse/drivers/xen/evtchn/evtchn.c Wed Mar 28 13:52:03
2007 +0100
@@ -56,6 +56,7 @@ struct per_user_data {
#define EVTCHN_RING_MASK(_i) ((_i)&(EVTCHN_RING_SIZE-1))
evtchn_port_t *ring;
unsigned int ring_cons, ring_prod, ring_overflow;
+ struct mutex ring_cons_mutex; /* protect against concurrent readers */
/* Processes wait on this queue when ring is empty. */
wait_queue_head_t evtchn_wait;
@@ -108,11 +109,16 @@ static ssize_t evtchn_read(struct file *
count = PAGE_SIZE;
for (;;) {
+ mutex_lock(&u->ring_cons_mutex);
+
+ rc = -EFBIG;
if (u->ring_overflow)
- return -EFBIG;
+ goto unlock_out;
if ((c = u->ring_cons) != (p = u->ring_prod))
break;
+
+ mutex_unlock(&u->ring_cons_mutex);
if (file->f_flags & O_NONBLOCK)
return -EAGAIN;
@@ -141,20 +147,24 @@ static ssize_t evtchn_read(struct file *
bytes2 = count - bytes1;
}
+ rc = -EFAULT;
if (copy_to_user(buf, &u->ring[EVTCHN_RING_MASK(c)], bytes1) ||
((bytes2 != 0) &&
copy_to_user(&buf[bytes1], &u->ring[0], bytes2)))
- return -EFAULT;
+ goto unlock_out;
u->ring_cons += (bytes1 + bytes2) / sizeof(evtchn_port_t);
-
- return bytes1 + bytes2;
+ rc = bytes1 + bytes2;
+
+ unlock_out:
+ mutex_unlock(&u->ring_cons_mutex);
+ return rc;
}
static ssize_t evtchn_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
- int rc, i;
+ int rc, i;
evtchn_port_t *kbuf = (evtchn_port_t *)__get_free_page(GFP_KERNEL);
struct per_user_data *u = file->private_data;
@@ -164,18 +174,16 @@ static ssize_t evtchn_write(struct file
/* Whole number of ports. */
count &= ~(sizeof(evtchn_port_t)-1);
- if (count == 0) {
- rc = 0;
+ rc = 0;
+ if (count == 0)
goto out;
- }
if (count > PAGE_SIZE)
count = PAGE_SIZE;
- if (copy_from_user(kbuf, buf, count) != 0) {
- rc = -EFAULT;
+ rc = -EFAULT;
+ if (copy_from_user(kbuf, buf, count) != 0)
goto out;
- }
spin_lock_irq(&port_user_lock);
for (i = 0; i < (count/sizeof(evtchn_port_t)); i++)
@@ -321,9 +329,11 @@ static int evtchn_ioctl(struct inode *in
case IOCTL_EVTCHN_RESET: {
/* Initialise the ring to empty. Clear errors. */
+ mutex_lock(&u->ring_cons_mutex);
spin_lock_irq(&port_user_lock);
u->ring_cons = u->ring_prod = u->ring_overflow = 0;
spin_unlock_irq(&port_user_lock);
+ mutex_unlock(&u->ring_cons_mutex);
rc = 0;
break;
}
@@ -370,6 +380,8 @@ static int evtchn_open(struct inode *ino
kfree(u);
return -ENOMEM;
}
+
+ mutex_init(&u->ring_cons_mutex);
filp->private_data = u;
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