diff options
Diffstat (limited to 'drivers/usb/core/devio.c')
| -rw-r--r-- | drivers/usb/core/devio.c | 26 |
1 files changed, 15 insertions, 11 deletions
diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c index 218621b9958e..ab6cc03a670b 100644 --- a/drivers/usb/core/devio.c +++ b/drivers/usb/core/devio.c @@ -59,6 +59,9 @@ #define USB_DEVICE_MAX USB_MAXBUS * 128 static struct class *usb_device_class; +/* Mutual exclusion for removal, open, and release */ +DEFINE_MUTEX(usbfs_mutex); + struct async { struct list_head asynclist; struct dev_state *ps; @@ -541,15 +544,13 @@ static int usbdev_open(struct inode *inode, struct file *file) struct dev_state *ps; int ret; - /* - * no locking necessary here, as chrdev_open has the kernel lock - * (still acquire the kernel lock for safety) - */ + /* Protect against simultaneous removal or release */ + mutex_lock(&usbfs_mutex); + ret = -ENOMEM; if (!(ps = kmalloc(sizeof(struct dev_state), GFP_KERNEL))) - goto out_nolock; + goto out; - lock_kernel(); ret = -ENOENT; /* check if we are called from a real node or usbfs */ if (imajor(inode) == USB_DEVICE_MAJOR) @@ -579,9 +580,8 @@ static int usbdev_open(struct inode *inode, struct file *file) list_add_tail(&ps->list, &dev->filelist); file->private_data = ps; out: - unlock_kernel(); - out_nolock: - return ret; + mutex_unlock(&usbfs_mutex); + return ret; } static int usbdev_release(struct inode *inode, struct file *file) @@ -591,7 +591,12 @@ static int usbdev_release(struct inode *inode, struct file *file) unsigned int ifnum; usb_lock_device(dev); + + /* Protect against simultaneous open */ + mutex_lock(&usbfs_mutex); list_del_init(&ps->list); + mutex_unlock(&usbfs_mutex); + for (ifnum = 0; ps->ifclaimed && ifnum < 8*sizeof(ps->ifclaimed); ifnum++) { if (test_bit(ifnum, &ps->ifclaimed)) @@ -600,9 +605,8 @@ static int usbdev_release(struct inode *inode, struct file *file) destroy_all_async(ps); usb_unlock_device(dev); usb_put_dev(dev); - ps->dev = NULL; kfree(ps); - return 0; + return 0; } static int proc_control(struct dev_state *ps, void __user *arg) |