@@ -1866,7 +1866,7 @@ static unsigned int comedi_poll(struct file *file, poll_table *wait)
mask = 0;
read_subdev = comedi_get_read_subdevice(dev_file_info);
- if (read_subdev) {
+ if (read_subdev && read_subdev->async) {
poll_wait(file, &read_subdev->async->wait_head, wait);
if (!read_subdev->busy
|| comedi_buf_read_n_available(read_subdev->async) > 0
@@ -1876,7 +1876,7 @@ static unsigned int comedi_poll(struct file *file, poll_table *wait)
}
}
write_subdev = comedi_get_write_subdevice(dev_file_info);
- if (write_subdev) {
+ if (write_subdev && write_subdev->async) {
poll_wait(file, &write_subdev->async->wait_head, wait);
comedi_buf_write_alloc(write_subdev->async,
write_subdev->async->prealloc_bufsz);
@@ -1918,7 +1918,7 @@ static ssize_t comedi_write(struct file *file, const char __user *buf,
}
s = comedi_get_write_subdevice(dev_file_info);
- if (s == NULL) {
+ if (!s || !s->async) {
retval = -EIO;
goto done;
}
@@ -2029,7 +2029,7 @@ static ssize_t comedi_read(struct file *file, char __user *buf, size_t nbytes,
}
s = comedi_get_read_subdevice(dev_file_info);
- if (s == NULL) {
+ if (!s || !s->async) {
retval = -EIO;
goto done;
}