From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1949313AbcBSQOR (ORCPT ); Fri, 19 Feb 2016 11:14:17 -0500 Received: from smtp73.iad3a.emailsrvr.com ([173.203.187.73]:51356 "EHLO smtp73.iad3a.emailsrvr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1949149AbcBSQOL (ORCPT ); Fri, 19 Feb 2016 11:14:11 -0500 X-Auth-ID: abbotti@mev.co.uk X-Sender-Id: abbotti@mev.co.uk From: Ian Abbott To: devel@driverdev.osuosl.org Cc: Greg Kroah-Hartman , Ian Abbott , H Hartley Sweeten , linux-kernel@vger.kernel.org Subject: [PATCH 4/8] staging: comedi: COMEDI_BUFINFO: force bytes_written to 0 if stopped Date: Fri, 19 Feb 2016 16:13:53 +0000 Message-Id: <1455898437-4640-5-git-send-email-abbotti@mev.co.uk> X-Mailer: git-send-email 2.7.0 In-Reply-To: <1455898437-4640-1-git-send-email-abbotti@mev.co.uk> References: <1455898437-4640-1-git-send-email-abbotti@mev.co.uk> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- 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 e625ef2..b7c9270 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 = -- 2.7.0