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Commit aaaaaadb authored by Stanislaw Gruszka's avatar Stanislaw Gruszka Committed by David S. Miller
Browse files

[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: default avatarStanislaw Gruszka <stf_xl@wp.pl>
Signed-off-by: default avatarChas Williams <chas@cmf.nrl.navy.mil>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 49693280

net/atm/common.c

+2 −2
Original line number Diff line number Diff line
@@ -427,12 +427,12 @@ int vcc_connect(struct socket *sock, int itf, short vpi, int vci) 
		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;

net/atm/resources.c

+17 −19
Original line number Diff line number Diff line
@@ -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 @@ static struct atm_dev *__atm_dev_lookup(int number) 


	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 *atm_dev_lookup(int number) 
{

	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 @@ struct atm_dev *atm_dev_register(const char *type, const struct atmdev_ops *ops, 
		    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 @@ struct atm_dev *atm_dev_register(const char *type, const struct atmdev_ops *ops, 
		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 @@ void atm_dev_deregister(struct atm_dev *dev) 


	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 @@ int atm_dev_ioctl(unsigned int cmd, void __user *arg) 
				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 @@ int atm_dev_ioctl(unsigned int cmd, void __user *arg) 
				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 @@ static __inline__ void *dev_get_idx(loff_t left) 


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)

net/atm/resources.h

+1 −2
Original line number Diff line number Diff line
@@ -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);