[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>
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4969328026
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aaaaaadbe7
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@ -427,12 +427,12 @@ int vcc_connect(struct socket *sock, int itf, short vpi, int vci)
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dev = try_then_request_module(atm_dev_lookup(itf), "atm-device-%d", itf);
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} else {
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dev = NULL;
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spin_lock(&atm_dev_lock);
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down(&atm_dev_mutex);
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if (!list_empty(&atm_devs)) {
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dev = list_entry(atm_devs.next, struct atm_dev, dev_list);
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atm_dev_hold(dev);
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}
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spin_unlock(&atm_dev_lock);
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up(&atm_dev_mutex);
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}
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if (!dev)
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return -ENODEV;
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@ -25,7 +25,7 @@
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LIST_HEAD(atm_devs);
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DEFINE_SPINLOCK(atm_dev_lock);
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DECLARE_MUTEX(atm_dev_mutex);
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static struct atm_dev *__alloc_atm_dev(const char *type)
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{
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@ -52,7 +52,7 @@ static struct atm_dev *__atm_dev_lookup(int number)
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list_for_each(p, &atm_devs) {
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dev = list_entry(p, struct atm_dev, dev_list);
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if ((dev->ops) && (dev->number == number)) {
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if (dev->number == number) {
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atm_dev_hold(dev);
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return dev;
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}
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@ -64,9 +64,9 @@ struct atm_dev *atm_dev_lookup(int number)
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{
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struct atm_dev *dev;
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spin_lock(&atm_dev_lock);
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down(&atm_dev_mutex);
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dev = __atm_dev_lookup(number);
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spin_unlock(&atm_dev_lock);
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up(&atm_dev_mutex);
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return dev;
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}
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@ -81,11 +81,11 @@ struct atm_dev *atm_dev_register(const char *type, const struct atmdev_ops *ops,
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type);
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return NULL;
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}
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spin_lock(&atm_dev_lock);
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down(&atm_dev_mutex);
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if (number != -1) {
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if ((inuse = __atm_dev_lookup(number))) {
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atm_dev_put(inuse);
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spin_unlock(&atm_dev_lock);
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up(&atm_dev_mutex);
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kfree(dev);
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return NULL;
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}
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@ -105,19 +105,17 @@ struct atm_dev *atm_dev_register(const char *type, const struct atmdev_ops *ops,
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memset(&dev->flags, 0, sizeof(dev->flags));
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memset(&dev->stats, 0, sizeof(dev->stats));
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atomic_set(&dev->refcnt, 1);
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list_add_tail(&dev->dev_list, &atm_devs);
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spin_unlock(&atm_dev_lock);
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if (atm_proc_dev_register(dev) < 0) {
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printk(KERN_ERR "atm_dev_register: "
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"atm_proc_dev_register failed for dev %s\n",
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type);
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spin_lock(&atm_dev_lock);
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list_del(&dev->dev_list);
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spin_unlock(&atm_dev_lock);
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up(&atm_dev_mutex);
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kfree(dev);
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return NULL;
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}
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list_add_tail(&dev->dev_list, &atm_devs);
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up(&atm_dev_mutex);
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return dev;
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}
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@ -129,9 +127,9 @@ void atm_dev_deregister(struct atm_dev *dev)
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atm_proc_dev_deregister(dev);
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spin_lock(&atm_dev_lock);
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down(&atm_dev_mutex);
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list_del(&dev->dev_list);
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spin_unlock(&atm_dev_lock);
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up(&atm_dev_mutex);
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warning_time = jiffies;
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while (atomic_read(&dev->refcnt) != 1) {
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@ -211,16 +209,16 @@ int atm_dev_ioctl(unsigned int cmd, void __user *arg)
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return -EFAULT;
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if (get_user(len, &iobuf->length))
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return -EFAULT;
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spin_lock(&atm_dev_lock);
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down(&atm_dev_mutex);
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list_for_each(p, &atm_devs)
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size += sizeof(int);
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if (size > len) {
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spin_unlock(&atm_dev_lock);
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up(&atm_dev_mutex);
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return -E2BIG;
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}
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tmp_buf = kmalloc(size, GFP_ATOMIC);
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if (!tmp_buf) {
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spin_unlock(&atm_dev_lock);
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up(&atm_dev_mutex);
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return -ENOMEM;
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}
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tmp_p = tmp_buf;
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@ -228,7 +226,7 @@ int atm_dev_ioctl(unsigned int cmd, void __user *arg)
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dev = list_entry(p, struct atm_dev, dev_list);
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*tmp_p++ = dev->number;
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}
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spin_unlock(&atm_dev_lock);
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up(&atm_dev_mutex);
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error = ((copy_to_user(buf, tmp_buf, size)) ||
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put_user(size, &iobuf->length))
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? -EFAULT : 0;
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@ -415,13 +413,13 @@ static __inline__ void *dev_get_idx(loff_t left)
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void *atm_dev_seq_start(struct seq_file *seq, loff_t *pos)
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{
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spin_lock(&atm_dev_lock);
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down(&atm_dev_mutex);
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return *pos ? dev_get_idx(*pos) : (void *) 1;
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}
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void atm_dev_seq_stop(struct seq_file *seq, void *v)
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{
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spin_unlock(&atm_dev_lock);
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up(&atm_dev_mutex);
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}
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void *atm_dev_seq_next(struct seq_file *seq, void *v, loff_t *pos)
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@ -11,8 +11,7 @@
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extern struct list_head atm_devs;
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extern spinlock_t atm_dev_lock;
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extern struct semaphore atm_dev_mutex;
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int atm_dev_ioctl(unsigned int cmd, void __user *arg);
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