Misc, phantom, fix poll

Return ERR even if there are pending data, but hw is not running.  Do not
decrement count in poll, do it in ioctl, where data are actually read.

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/misc/phantom.c

@@ -169,6 +169,7 @@ static long phantom_ioctl(struct file *file, unsigned int cmd,
 		for (i = 0; i < m; i++)
 			if (rs.mask & BIT(i))
 				rs.values[i] = ioread32(dev->iaddr + i);
+		atomic_set(&dev->counter, 0);
 		spin_unlock_irqrestore(&dev->regs_lock, flags);
 
 		if (copy_to_user(argp, &rs, sizeof(rs)))
@@ -254,11 +255,12 @@ static unsigned int phantom_poll(struct file *file, poll_table *wait)
 
 	pr_debug("phantom_poll: %d\n", atomic_read(&dev->counter));
 	poll_wait(file, &dev->wait, wait);
-	if (atomic_read(&dev->counter)) {
+
+	if (!(dev->status & PHB_RUNNING))
+		mask = POLLERR;
+	else if (atomic_read(&dev->counter))
 		mask = POLLIN | POLLRDNORM;
-		atomic_dec(&dev->counter);
+
-	} else if ((dev->status & PHB_RUNNING) == 0)
-		mask = POLLIN | POLLRDNORM | POLLERR;
 	pr_debug("phantom_poll end: %x/%d\n", mask, atomic_read(&dev->counter));
 
 	return mask;