Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754744Ab3JUIxo (ORCPT ); Mon, 21 Oct 2013 04:53:44 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:39925 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754656Ab3JUIxe (ORCPT ); Mon, 21 Oct 2013 04:53:34 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Ian Abbott" , "Greg Kroah-Hartman" Date: Mon, 21 Oct 2013 09:46:28 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 146/149] staging: comedi: ni_65xx: (bug fix) confine insn_bits to one subdevice In-Reply-To: X-SA-Exim-Connect-IP: 212.20.242.100 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3615 Lines: 86 3.2.52-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Ian Abbott commit 677a31565692d596ef42ea589b53ba289abf4713 upstream. The `insn_bits` handler `ni_65xx_dio_insn_bits()` has a `for` loop that currently writes (optionally) and reads back up to 5 "ports" consisting of 8 channels each. It reads up to 32 1-bit channels but can only read and write a whole port at once - it needs to handle up to 5 ports as the first channel it reads might not be aligned on a port boundary. It breaks out of the loop early if the next port it handles is beyond the final port on the card. It also breaks out early on the 5th port in the loop if the first channel was aligned. Unfortunately, it doesn't check that the current port it is dealing with belongs to the comedi subdevice the `insn_bits` handler is acting on. That's a bug. Redo the `for` loop to terminate after the final port belonging to the subdevice, changing the loop variable in the process to simplify things a bit. The `for` loop could now try and handle more than 5 ports if the subdevice has more than 40 channels, but the test `if (bitshift >= 32)` ensures it will break out early after 4 or 5 ports (depending on whether the first channel is aligned on a port boundary). (`bitshift` will be between -7 and 7 inclusive on the first iteration, increasing by 8 for each subsequent operation.) Signed-off-by: Ian Abbott Signed-off-by: Greg Kroah-Hartman [Ian Abbott: This patch applies to kernels 2.6.34.y through to 3.5.y inclusive.] Signed-off-by: Ben Hutchings --- drivers/staging/comedi/drivers/ni_65xx.c | 25 ++++++++++--------------- 1 file changed, 10 insertions(+), 15 deletions(-) --- a/drivers/staging/comedi/drivers/ni_65xx.c +++ b/drivers/staging/comedi/drivers/ni_65xx.c @@ -411,29 +411,25 @@ static int ni_65xx_dio_insn_bits(struct struct comedi_subdevice *s, struct comedi_insn *insn, unsigned int *data) { - unsigned base_bitfield_channel; - const unsigned max_ports_per_bitfield = 5; + int base_bitfield_channel; unsigned read_bits = 0; - unsigned j; + int last_port_offset = ni_65xx_port_by_channel(s->n_chan - 1); + int port_offset; + if (insn->n != 2) return -EINVAL; base_bitfield_channel = CR_CHAN(insn->chanspec); - for (j = 0; j < max_ports_per_bitfield; ++j) { - const unsigned port_offset = - ni_65xx_port_by_channel(base_bitfield_channel) + j; - const unsigned port = - sprivate(s)->base_port + port_offset; - unsigned base_port_channel; + for (port_offset = ni_65xx_port_by_channel(base_bitfield_channel); + port_offset <= last_port_offset; port_offset++) { + unsigned port = sprivate(s)->base_port + port_offset; + int base_port_channel = port_offset * ni_65xx_channels_per_port; unsigned port_mask, port_data, port_read_bits; - int bitshift; - if (port >= ni_65xx_total_num_ports(board(dev))) + int bitshift = base_port_channel - base_bitfield_channel; + + if (bitshift >= 32) break; - base_port_channel = port_offset * ni_65xx_channels_per_port; port_mask = data[0]; port_data = data[1]; - bitshift = base_port_channel - base_bitfield_channel; - if (bitshift >= 32 || bitshift <= -32) - break; if (bitshift > 0) { port_mask >>= bitshift; port_data >>= bitshift; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/