diff options
| -rw-r--r-- | drivers/usb/core/devices.c | 66 |
1 files changed, 24 insertions, 42 deletions
diff --git a/drivers/usb/core/devices.c b/drivers/usb/core/devices.c index c83c975152a6..6053a8b730cd 100644 --- a/drivers/usb/core/devices.c +++ b/drivers/usb/core/devices.c @@ -117,9 +117,21 @@ static const char *format_endpt = * However, these will come from functions that return ptrs to each of them. */ -static DECLARE_WAIT_QUEUE_HEAD(deviceconndiscwq); -/* guarded by usbfs_mutex */ -static unsigned int conndiscevcnt; +/* + * Wait for an connect/disconnect event to happen. We initialize + * the event counter with an odd number, and each event will increment + * the event counter by two, so it will always _stay_ odd. That means + * that it will never be zero, so "event 0" will never match a current + * event, and thus 'poll' will always trigger as readable for the first + * time it gets called. + */ +static struct device_connect_event { + atomic_t count; + wait_queue_head_t wait; +} device_event = { + .count = ATOMIC_INIT(1), + .wait = __WAIT_QUEUE_HEAD_INITIALIZER(device_event.wait) +}; /* this struct stores the poll state for <mountpoint>/devices pollers */ struct usb_device_status { @@ -157,10 +169,8 @@ static const struct class_info clas_info[] = void usbfs_conn_disc_event(void) { - mutex_lock(&usbfs_mutex); - conndiscevcnt++; - mutex_unlock(&usbfs_mutex); - wake_up(&deviceconndiscwq); + atomic_add(2, &device_event.count); + wake_up(&device_event.wait); } static const char *class_decode(const int class) @@ -632,42 +642,16 @@ static ssize_t usb_device_read(struct file *file, char __user *buf, static unsigned int usb_device_poll(struct file *file, struct poll_table_struct *wait) { - struct usb_device_status *st; - unsigned int mask = 0; - - mutex_lock(&usbfs_mutex); - st = file->private_data; - if (!st) { - st = kmalloc(sizeof(struct usb_device_status), GFP_KERNEL); - if (!st) { - mutex_unlock(&usbfs_mutex); - return POLLIN; - } - - st->lastev = conndiscevcnt; - file->private_data = st; - mask = POLLIN; - } + unsigned int event_count; - if (file->f_mode & FMODE_READ) - poll_wait(file, &deviceconndiscwq, wait); - if (st->lastev != conndiscevcnt) - mask |= POLLIN; - st->lastev = conndiscevcnt; - mutex_unlock(&usbfs_mutex); - return mask; -} + poll_wait(file, &device_event.wait, wait); -static int usb_device_open(struct inode *inode, struct file *file) -{ - file->private_data = NULL; - return 0; -} + event_count = atomic_read(&device_event.count); + if (file->f_version != event_count) { + file->f_version = event_count; + return POLLIN | POLLRDNORM; + } -static int usb_device_release(struct inode *inode, struct file *file) -{ - kfree(file->private_data); - file->private_data = NULL; return 0; } @@ -699,6 +683,4 @@ const struct file_operations usbfs_devices_fops = { .llseek = usb_device_lseek, .read = usb_device_read, .poll = usb_device_poll, - .open = usb_device_open, - .release = usb_device_release, }; |