[ALSA] return ENODEV for disconnected devices

Modules: ALSA Core

Add dummy functions that return -ENODEV for the struct file_operations
of a disconnected device.  Without such functions, userspace would get
ENOTTY.
Signed-off-by: NClemens Ladisch <clemens@ladisch.de>

sound/core/init.c

@@ -169,11 +169,44 @@ struct snd_card *snd_card_new(int idx, const char *xid,
       	return NULL;
 }
 
+static loff_t snd_disconnect_llseek(struct file *file, loff_t offset, int orig)
+{
+	return -ENODEV;
+}
+
+static ssize_t snd_disconnect_read(struct file *file, char __user *buf,
+				   size_t count, loff_t *offset)
+{
+	return -ENODEV;
+}
+
+static ssize_t snd_disconnect_write(struct file *file, const char __user *buf,
+				    size_t count, loff_t *offset)
+{
+	return -ENODEV;
+}
+
 static unsigned int snd_disconnect_poll(struct file * file, poll_table * wait)
 {
 	return POLLERR | POLLNVAL;
 }
 
+static long snd_disconnect_ioctl(struct file *file,
+				 unsigned int cmd, unsigned long arg)
+{
+	return -ENODEV;
+}
+
+static int snd_disconnect_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	return -ENODEV;
+}
+
+static int snd_disconnect_fasync(int fd, struct file *file, int on)
+{
+	return -ENODEV;
+}
+
 /**
  *  snd_card_disconnect - disconnect all APIs from the file-operations (user space)
  *  @card: soundcard structure
@@ -224,7 +257,16 @@ int snd_card_disconnect(struct snd_card *card)
 		memset(f_ops, 0, sizeof(*f_ops));
 		f_ops->owner = file->f_op->owner;
 		f_ops->release = file->f_op->release;
+		f_ops->llseek = snd_disconnect_llseek;
+		f_ops->read = snd_disconnect_read;
+		f_ops->write = snd_disconnect_write;
 		f_ops->poll = snd_disconnect_poll;
+		f_ops->unlocked_ioctl = snd_disconnect_ioctl;
+#ifdef CONFIG_COMPAT
+		f_ops->compat_ioctl = snd_disconnect_ioctl;
+#endif
+		f_ops->mmap = snd_disconnect_mmap;
+		f_ops->fasync = snd_disconnect_fasync;
 
 		s_f_ops->next = card->s_f_ops;
 		card->s_f_ops = s_f_ops;