From bb0c6bfac7d4aebb6525b285ca03c4316d72647a Mon Sep 17 00:00:00 2001 From: Ian Abbott Date: Fri, 19 Feb 2016 16:13:53 +0000 Subject: [PATCH] staging: comedi: COMEDI_BUFINFO: force bytes_written to 0 if stopped The `COMEDI_BUFINFO` ioctl is used to advance the current position in the buffer by a specified amount (which can be 0) and get the new position. On input, the `bytes_written` member of `struct comedi_bufinfo` specifies the amount to advance the "write" position for an asynchronous command in the "write" direction. On output, the member indicates the amount the "write" position has actually been advanced. Advancing the "write" position is current done even if the command has stopped and cannot use any more written data. Change it to force the amount successfully written to 0 in that case. Signed-off-by: Ian Abbott Signed-off-by: Greg Kroah-Hartman --- 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 e625ef2bcb7f..b7c9270f9e92 100644 --- a/drivers/staging/comedi/comedi_fops.c +++ b/drivers/staging/comedi/comedi_fops.c @@ -1155,6 +1155,8 @@ static int do_bufinfo_ioctl(struct comedi_device *dev, bi.bytes_written = 0; } else { /* command was set up in "write" direction */ + if (!comedi_is_subdevice_running(s)) + bi.bytes_written = 0; if (bi.bytes_written) { comedi_buf_write_alloc(s, bi.bytes_written); bi.bytes_written = -- 2.30.2