diff options
| -rw-r--r-- | drivers/usb/class/cdc-wdm.c | 16 |
1 files changed, 11 insertions, 5 deletions
diff --git a/drivers/usb/class/cdc-wdm.c b/drivers/usb/class/cdc-wdm.c index b27bbb957e16..7ca54d4dea92 100644 --- a/drivers/usb/class/cdc-wdm.c +++ b/drivers/usb/class/cdc-wdm.c @@ -391,7 +391,7 @@ outnl: static ssize_t wdm_read (struct file *file, char __user *buffer, size_t count, loff_t *ppos) { - int rv, cntr = 0; + int rv, cntr; int i = 0; struct wdm_device *desc = file->private_data; @@ -400,7 +400,8 @@ static ssize_t wdm_read if (rv < 0) return -ERESTARTSYS; - if (desc->length == 0) { + cntr = ACCESS_ONCE(desc->length); + if (cntr == 0) { desc->read = 0; retry: if (test_bit(WDM_DISCONNECTING, &desc->flags)) { @@ -455,25 +456,30 @@ retry: goto retry; } clear_bit(WDM_READ, &desc->flags); + cntr = desc->length; spin_unlock_irq(&desc->iuspin); } - cntr = count > desc->length ? desc->length : count; + if (cntr > count) + cntr = count; rv = copy_to_user(buffer, desc->ubuf, cntr); if (rv > 0) { rv = -EFAULT; goto err; } + spin_lock_irq(&desc->iuspin); + for (i = 0; i < desc->length - cntr; i++) desc->ubuf[i] = desc->ubuf[i + cntr]; - spin_lock_irq(&desc->iuspin); desc->length -= cntr; - spin_unlock_irq(&desc->iuspin); /* in case we had outstanding data */ if (!desc->length) clear_bit(WDM_READ, &desc->flags); + + spin_unlock_irq(&desc->iuspin); + rv = cntr; err: |