staging: comedi: check actual data direction for COMEDI_BUFINFO ioctl

`do_bufinfo_ioctl()` handled the `COMEDI_BUFINFO` ioctl.  It is supposed
to update the read or write positions in the buffer depending on the
direction of data transfer set up by the asynchronous command.
Currently it checks the `SDF_CMD_READ` and `SDF_CMD_WRITE` subdevice
flags.  That's fine for most subdevices - the ones that only support one
direction, but is incorrect for those subdevices that allow the command
to be set up in either direction.  Since we now set the `CMDF_WRITE`
flag according to the data transfer direction of the current command
running on the subdevice, check that flag instead.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c
index 63afd78..704ae25 100644 (file)
--- a/drivers/staging/comedi/comedi_fops.c
+++ b/drivers/staging/comedi/comedi_fops.c
@@ -991,7 +991,7 @@ static int do_bufinfo_ioctl(struct comedi_device *dev,
        if (s->busy != file)
                return -EACCES;
 
-       if (bi.bytes_read && (s->subdev_flags & SDF_CMD_READ)) {
+       if (bi.bytes_read && !(async->cmd.flags & CMDF_WRITE)) {
                bi.bytes_read = comedi_buf_read_alloc(s, bi.bytes_read);
                comedi_buf_read_free(s, bi.bytes_read);
 
@@ -1001,7 +1001,7 @@ static int do_bufinfo_ioctl(struct comedi_device *dev,
                }
        }
 
-       if (bi.bytes_written && (s->subdev_flags & SDF_CMD_WRITE)) {
+       if (bi.bytes_written && (async->cmd.flags & CMDF_WRITE)) {
                bi.bytes_written =
                    comedi_buf_write_alloc(s, bi.bytes_written);
                comedi_buf_write_free(s, bi.bytes_written);