diff options
Diffstat (limited to 'drivers/staging/comedi/comedi_fops.c')
| -rw-r--r-- | drivers/staging/comedi/comedi_fops.c | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c index c74c50a6e52d..49c46651ad23 100644 --- a/drivers/staging/comedi/comedi_fops.c +++ b/drivers/staging/comedi/comedi_fops.c @@ -2567,14 +2567,17 @@ static ssize_t comedi_read(struct file *file, char __user *buf, size_t nbytes, * sufficient (unless there have been 2**32 detaches in the * meantime!), but check the subdevice pointer as well just in * case. + * + * Also check the subdevice is still in a suitable state to + * become non-busy in case it changed behind our back. */ new_s = comedi_file_read_subdevice(file); if (dev->attached && old_detach_count == dev->detach_count && - s == new_s && new_s->async == async) { - if (become_nonbusy || - comedi_buf_read_n_available(s) == 0) - do_become_nonbusy(dev, s); - } + s == new_s && new_s->async == async && s->busy == file && + !(async->cmd.flags & CMDF_WRITE) && + !comedi_is_subdevice_running(s) && + comedi_buf_read_n_available(s) == 0) + do_become_nonbusy(dev, s); mutex_unlock(&dev->mutex); } out: |