`comedi_poll()` handles the poll() file operation for comedi devices. If no asynchronous command has been set up on the current "read" subdevice, it sets the `POLLIN` and `POLLRDNORM` bits in the return value to indicate that the read() file operation would not block as it would return an error. Add a check so it also does that if the asynchronous command has been set up in the "write" direction as that also causes the read() file operation to return an error.
Similarly, if no asynchronous command has need set up on the current "write" subdevice, it sets the `POLLOUT` and `POLLWRNORM` bits in the return value to indicate that the write() file operation would not block as it would return an error. Add a check so it also does that if the asynchronous command has been set up in the "read" direction as that also causes the write() file operation to return an error. Signed-off-by: Ian Abbott <[email protected]> --- drivers/staging/comedi/comedi_fops.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c index 6328965..d55f709 100644 --- a/drivers/staging/comedi/comedi_fops.c +++ b/drivers/staging/comedi/comedi_fops.c @@ -2017,6 +2017,7 @@ static unsigned int comedi_poll(struct file *file, poll_table *wait) if (s && s->async) { poll_wait(file, &s->async->wait_head, wait); if (!s->busy || !comedi_is_subdevice_running(s) || + (s->async->cmd.flags & CMDF_WRITE) || comedi_buf_read_n_available(s) > 0) mask |= POLLIN | POLLRDNORM; } @@ -2028,6 +2029,7 @@ static unsigned int comedi_poll(struct file *file, poll_table *wait) poll_wait(file, &s->async->wait_head, wait); comedi_buf_write_alloc(s, s->async->prealloc_bufsz); if (!s->busy || !comedi_is_subdevice_running(s) || + !(s->async->cmd.flags & CMDF_WRITE) || comedi_buf_write_n_allocated(s) >= bps) mask |= POLLOUT | POLLWRNORM; } -- 2.1.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
