[ATM]: avoid race conditions related to atm_devs list
Use semaphore to protect atm_devs list, as no one need access to it from
interrupt context. Avoid race conditions between atm_dev_register(),
atm_dev_lookup() and atm_dev_deregister(). Fix double spin_unlock() bug.
Signed-off-by: Stanislaw Gruszka <stf_xl@wp.pl>
Signed-off-by: Chas Williams <chas@cmf.nrl.navy.mil>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/atm/common.c b/net/atm/common.c
index db9318f..9e016f4 100644
--- a/net/atm/common.c
+++ b/net/atm/common.c
@@ -427,12 +427,12 @@
dev = try_then_request_module(atm_dev_lookup(itf), "atm-device-%d", itf);
} else {
dev = NULL;
- spin_lock(&atm_dev_lock);
+ down(&atm_dev_mutex);
if (!list_empty(&atm_devs)) {
dev = list_entry(atm_devs.next, struct atm_dev, dev_list);
atm_dev_hold(dev);
}
- spin_unlock(&atm_dev_lock);
+ up(&atm_dev_mutex);
}
if (!dev)
return -ENODEV;
diff --git a/net/atm/resources.c b/net/atm/resources.c
index 35f3ceb..ad533b0 100644
--- a/net/atm/resources.c
+++ b/net/atm/resources.c
@@ -25,7 +25,7 @@
LIST_HEAD(atm_devs);
-DEFINE_SPINLOCK(atm_dev_lock);
+DECLARE_MUTEX(atm_dev_mutex);
static struct atm_dev *__alloc_atm_dev(const char *type)
{
@@ -52,7 +52,7 @@
list_for_each(p, &atm_devs) {
dev = list_entry(p, struct atm_dev, dev_list);
- if ((dev->ops) && (dev->number == number)) {
+ if (dev->number == number) {
atm_dev_hold(dev);
return dev;
}
@@ -64,9 +64,9 @@
{
struct atm_dev *dev;
- spin_lock(&atm_dev_lock);
+ down(&atm_dev_mutex);
dev = __atm_dev_lookup(number);
- spin_unlock(&atm_dev_lock);
+ up(&atm_dev_mutex);
return dev;
}
@@ -81,11 +81,11 @@
type);
return NULL;
}
- spin_lock(&atm_dev_lock);
+ down(&atm_dev_mutex);
if (number != -1) {
if ((inuse = __atm_dev_lookup(number))) {
atm_dev_put(inuse);
- spin_unlock(&atm_dev_lock);
+ up(&atm_dev_mutex);
kfree(dev);
return NULL;
}
@@ -105,19 +105,17 @@
memset(&dev->flags, 0, sizeof(dev->flags));
memset(&dev->stats, 0, sizeof(dev->stats));
atomic_set(&dev->refcnt, 1);
- list_add_tail(&dev->dev_list, &atm_devs);
- spin_unlock(&atm_dev_lock);
if (atm_proc_dev_register(dev) < 0) {
printk(KERN_ERR "atm_dev_register: "
"atm_proc_dev_register failed for dev %s\n",
type);
- spin_lock(&atm_dev_lock);
- list_del(&dev->dev_list);
- spin_unlock(&atm_dev_lock);
+ up(&atm_dev_mutex);
kfree(dev);
return NULL;
}
+ list_add_tail(&dev->dev_list, &atm_devs);
+ up(&atm_dev_mutex);
return dev;
}
@@ -129,9 +127,9 @@
atm_proc_dev_deregister(dev);
- spin_lock(&atm_dev_lock);
+ down(&atm_dev_mutex);
list_del(&dev->dev_list);
- spin_unlock(&atm_dev_lock);
+ up(&atm_dev_mutex);
warning_time = jiffies;
while (atomic_read(&dev->refcnt) != 1) {
@@ -211,16 +209,16 @@
return -EFAULT;
if (get_user(len, &iobuf->length))
return -EFAULT;
- spin_lock(&atm_dev_lock);
+ down(&atm_dev_mutex);
list_for_each(p, &atm_devs)
size += sizeof(int);
if (size > len) {
- spin_unlock(&atm_dev_lock);
+ up(&atm_dev_mutex);
return -E2BIG;
}
tmp_buf = kmalloc(size, GFP_ATOMIC);
if (!tmp_buf) {
- spin_unlock(&atm_dev_lock);
+ up(&atm_dev_mutex);
return -ENOMEM;
}
tmp_p = tmp_buf;
@@ -228,7 +226,7 @@
dev = list_entry(p, struct atm_dev, dev_list);
*tmp_p++ = dev->number;
}
- spin_unlock(&atm_dev_lock);
+ up(&atm_dev_mutex);
error = ((copy_to_user(buf, tmp_buf, size)) ||
put_user(size, &iobuf->length))
? -EFAULT : 0;
@@ -415,13 +413,13 @@
void *atm_dev_seq_start(struct seq_file *seq, loff_t *pos)
{
- spin_lock(&atm_dev_lock);
+ down(&atm_dev_mutex);
return *pos ? dev_get_idx(*pos) : (void *) 1;
}
void atm_dev_seq_stop(struct seq_file *seq, void *v)
{
- spin_unlock(&atm_dev_lock);
+ up(&atm_dev_mutex);
}
void *atm_dev_seq_next(struct seq_file *seq, void *v, loff_t *pos)
diff --git a/net/atm/resources.h b/net/atm/resources.h
index 1291061..b7fb82a 100644
--- a/net/atm/resources.h
+++ b/net/atm/resources.h
@@ -11,8 +11,7 @@
extern struct list_head atm_devs;
-extern spinlock_t atm_dev_lock;
-
+extern struct semaphore atm_dev_mutex;
int atm_dev_ioctl(unsigned int cmd, void __user *arg);