diff options
| author | Al Viro <viro@zeniv.linux.org.uk> | 2013-04-16 01:18:17 +0400 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2013-04-29 23:41:49 +0400 |
| commit | ebb06be16bc9a1e66a010ca50c75c5128bafb4b1 (patch) | |
| tree | 3a9212bb7f267519242b3f66420cb98527edee41 | |
| parent | 1678ec00a632f8b9204e28e5c506128881171604 (diff) | |
| download | linux-ebb06be16bc9a1e66a010ca50c75c5128bafb4b1.tar.xz | |
mISDN: fix mISDN_read()/mISDN_read() race
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
| -rw-r--r-- | drivers/isdn/mISDN/timerdev.c | 23 |
1 files changed, 14 insertions, 9 deletions
diff --git a/drivers/isdn/mISDN/timerdev.c b/drivers/isdn/mISDN/timerdev.c index ddb8adcd5fbb..da2aa376a3a3 100644 --- a/drivers/isdn/mISDN/timerdev.c +++ b/drivers/isdn/mISDN/timerdev.c @@ -102,36 +102,41 @@ static ssize_t mISDN_read(struct file *filep, char __user *buf, size_t count, loff_t *off) { struct mISDNtimerdev *dev = filep->private_data; + struct list_head *list = &dev->expired; struct mISDNtimer *timer; - u_long flags; int ret = 0; if (*debug & DEBUG_TIMER) printk(KERN_DEBUG "%s(%p, %p, %d, %p)\n", __func__, filep, buf, (int)count, off); - if (list_empty(&dev->expired) && (dev->work == 0)) { + if (count < sizeof(int)) + return -ENOSPC; + + spin_lock_irq(&dev->lock); + while (list_empty(list) && (dev->work == 0)) { + spin_unlock_irq(&dev->lock); if (filep->f_flags & O_NONBLOCK) return -EAGAIN; wait_event_interruptible(dev->wait, (dev->work || - !list_empty(&dev->expired))); + !list_empty(list))); if (signal_pending(current)) return -ERESTARTSYS; + spin_lock_irq(&dev->lock); } - if (count < sizeof(int)) - return -ENOSPC; if (dev->work) dev->work = 0; - if (!list_empty(&dev->expired)) { - spin_lock_irqsave(&dev->lock, flags); - timer = (struct mISDNtimer *)dev->expired.next; + if (!list_empty(list)) { + timer = list_first_entry(list, struct mISDNtimer, list); list_del(&timer->list); - spin_unlock_irqrestore(&dev->lock, flags); + spin_unlock_irq(&dev->lock); if (put_user(timer->id, (int __user *)buf)) ret = -EFAULT; else ret = sizeof(int); kfree(timer); + } else { + spin_unlock_irq(&dev->lock); } return ret; } |