From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E1752ECDFB8 for ; Fri, 20 Jul 2018 19:23:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9A4EB20661 for ; Fri, 20 Jul 2018 19:23:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9A4EB20661 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=codethink.co.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388395AbeGTUN0 (ORCPT ); Fri, 20 Jul 2018 16:13:26 -0400 Received: from imap1.codethink.co.uk ([176.9.8.82]:46371 "EHLO imap1.codethink.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388006AbeGTUNZ (ORCPT ); Fri, 20 Jul 2018 16:13:25 -0400 Received: from [148.252.241.226] (helo=xylophone) by imap1.codethink.co.uk with esmtpsa (Exim 4.84_2 #1 (Debian)) id 1fgb0C-0001fn-PF; Fri, 20 Jul 2018 20:23:44 +0100 Message-ID: <1532114624.21552.43.camel@codethink.co.uk> Subject: Re: [PATCH 4.4 101/105] spi: Fix scatterlist elements size in spi_map_buf From: Ben Hutchings To: Greg Kroah-Hartman , linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org, Maxime Chevallier , Mark Brown , Sudip Mukherjee Date: Fri, 20 Jul 2018 20:23:44 +0100 In-Reply-To: <20180701153156.693937436@linuxfoundation.org> References: <20180701153149.382300170@linuxfoundation.org> <20180701153156.693937436@linuxfoundation.org> Organization: Codethink Ltd. Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.22.6-1+deb9u1 Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 2018-07-01 at 18:02 +0200, Greg Kroah-Hartman wrote: > 4.4-stable review patch.  If anyone has any objections, please let me know. > > ------------------ > > From: Maxime Chevallier > > commit ce99319a182fe766be67f96338386f3ec73e321c upstream. > > When SPI transfers can be offloaded using DMA, the SPI core need to > build a scatterlist to make sure that the buffer to be transferred is > dma-able. > > This patch fixes the scatterlist entry size computation in the case > where the maximum acceptable scatterlist entry supported by the DMA > controller is less than PAGE_SIZE, when the buffer is vmalloced. > > For each entry, the actual size is given by the minimum between the > desc_len (which is the max buffer size supported by the DMA controller) > and the remaining buffer length until we cross a page boundary. > > Fixes: 65598c13fd66 ("spi: Fix per-page mapping of unaligned vmalloc-ed buffer") > Signed-off-by: Maxime Chevallier > Signed-off-by: Mark Brown > Cc: stable@vger.kernel.org > Signed-off-by: Sudip Mukherjee > Signed-off-by: Greg Kroah-Hartman > --- >  drivers/spi/spi.c |   10 ++++++++-- >  1 file changed, 8 insertions(+), 2 deletions(-) > > --- a/drivers/spi/spi.c > +++ b/drivers/spi/spi.c > @@ -707,8 +707,14 @@ static int spi_map_buf(struct spi_master >   for (i = 0; i < sgs; i++) { >   >   if (vmalloced_buf) { > - min = min_t(size_t, > -     len, desc_len - offset_in_page(buf)); > + /* > +  * Next scatterlist entry size is the minimum between > +  * the desc_len and the remaining buffer length that > +  * fits in a page. > +  */ > + min = min_t(size_t, desc_len, > +     min_t(size_t, len, > +   PAGE_SIZE - offset_in_page(buf))); >   vm_page = vmalloc_to_page(buf); >   if (!vm_page) { >   sg_free_table(sgt); I think this makes sense upstream, but in 4.4 it seems to be a no-op since desc_len is always set to PAGE_SIZE when vmalloced_buf is true. This fix depends on (at least) commit df88e91bbfd1 "spi: respect the maximum segment size of DMA device" which went into 4.6. Ben. -- Ben Hutchings, Software Developer   Codethink Ltd https://www.codethink.co.uk/ Dale House, 35 Dale Street Manchester, M1 2HF, United Kingdom