From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1427789AbcBSQQi (ORCPT ); Fri, 19 Feb 2016 11:16:38 -0500 Received: from smtp73.iad3a.emailsrvr.com ([173.203.187.73]:38711 "EHLO smtp73.iad3a.emailsrvr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1949077AbcBSQOJ (ORCPT ); Fri, 19 Feb 2016 11:14:09 -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 2/8] staging: comedi: COMEDI_BUFINFO: force bytes_read or bytes_written to 0 Date: Fri, 19 Feb 2016 16:13:51 +0000 Message-Id: <1455898437-4640-3-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_read` member of `struct comedi_bufinfo` specifies the amount to advance the "read" position for an asynchronous command in the "read" direction, and the `bytes_written` member specifies the amount to advance the "write" position for a command in the "write" direction. The handler `do_bufinfo_ioctl()` may adjust these by the amount the position is actually advanced before copying them back to the user. Currently, it ignores the specified `bytes_read` value for a command in the "write" direction, and ignores the specified `bytes_written` for a command in the "read" direction, so the values copied back to the user are unchanged. Change it to force the ignored value to 0 before copying the values back to the user. Signed-off-by: Ian Abbott --- drivers/staging/comedi/comedi_fops.c | 30 ++++++++++++++++++------------ 1 file changed, 18 insertions(+), 12 deletions(-) diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c index 2cfb61e..04d6040 100644 --- a/drivers/staging/comedi/comedi_fops.c +++ b/drivers/staging/comedi/comedi_fops.c @@ -1141,19 +1141,25 @@ static int do_bufinfo_ioctl(struct comedi_device *dev, if (s->busy != file) return -EACCES; - if (bi.bytes_read && !(async->cmd.flags & CMDF_WRITE)) { - comedi_buf_read_alloc(s, bi.bytes_read); - bi.bytes_read = comedi_buf_read_free(s, bi.bytes_read); - - if (comedi_is_subdevice_idle(s) && - comedi_buf_read_n_available(s) == 0) { - do_become_nonbusy(dev, s); + if (!(async->cmd.flags & CMDF_WRITE)) { + /* command was set up in "read" direction */ + if (bi.bytes_read) { + comedi_buf_read_alloc(s, bi.bytes_read); + bi.bytes_read = comedi_buf_read_free(s, bi.bytes_read); + + if (comedi_is_subdevice_idle(s) && + comedi_buf_read_n_available(s) == 0) + do_become_nonbusy(dev, s); } - } - - if (bi.bytes_written && (async->cmd.flags & CMDF_WRITE)) { - comedi_buf_write_alloc(s, bi.bytes_written); - bi.bytes_written = comedi_buf_write_free(s, bi.bytes_written); + bi.bytes_written = 0; + } else { + /* command was set up in "write" direction */ + if (bi.bytes_written) { + comedi_buf_write_alloc(s, bi.bytes_written); + bi.bytes_written = + comedi_buf_write_free(s, bi.bytes_written); + } + bi.bytes_read = 0; } copyback_position: -- 2.7.0