From aaaaaadbe7a663d110814db50fcbe7d320eb4c32 Mon Sep 17 00:00:00 2001 From: Stanislaw Gruszka Date: Tue, 29 Nov 2005 16:16:21 -0800 Subject: [PATCH] [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 Signed-off-by: Chas Williams Signed-off-by: David S. Miller --- net/atm/common.c | 4 ++-- net/atm/resources.c | 36 +++++++++++++++++------------------- net/atm/resources.h | 3 +-- 3 files changed, 20 insertions(+), 23 deletions(-) diff --git a/net/atm/common.c b/net/atm/common.c index db9318fc60..9e016f404e 100644 --- a/net/atm/common.c +++ b/net/atm/common.c @@ -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; diff --git a/net/atm/resources.c b/net/atm/resources.c index 35f3ceb768..ad533b02b8 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 @@ 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) diff --git a/net/atm/resources.h b/net/atm/resources.h index 12910619db..b7fb82a93b 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); -- 2.39.5