staging: comedi: support vm_access_process for mmap'd buffer

If a process that has mmap'd a COMEDI buffer is being run under a
debugger such as GDB, the buffer contents are inaccessible from the
debugger.  Support the `access()` VM operation to allow the buffer
contents to be accessed by another process.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/staging/comedi/comedi_internal.h b/drivers/staging/comedi/comedi_internal.h
index 534415e..6246f4a 100644
--- a/drivers/staging/comedi/comedi_internal.h
+++ b/drivers/staging/comedi/comedi_internal.h
@@ -29,6 +29,8 @@ void comedi_buf_reset(struct comedi_subdevice *s);
 bool comedi_buf_is_mmapped(struct comedi_subdevice *s);
 void comedi_buf_map_get(struct comedi_buf_map *bm);
 int comedi_buf_map_put(struct comedi_buf_map *bm);
+int comedi_buf_map_access(struct comedi_buf_map *bm, unsigned long offset,
+			  void *buf, int len, int write);
 struct comedi_buf_map *comedi_buf_map_from_subdev_get(
 		struct comedi_subdevice *s);
 unsigned int comedi_buf_write_n_available(struct comedi_subdevice *s);