Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754041AbcDVNnd (ORCPT ); Fri, 22 Apr 2016 09:43:33 -0400 Received: from hqemgate15.nvidia.com ([216.228.121.64]:2942 "EHLO hqemgate15.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752972AbcDVNnb (ORCPT ); Fri, 22 Apr 2016 09:43:31 -0400 X-PGP-Universal: processed; by hqnvupgp07.nvidia.com on Fri, 22 Apr 2016 06:43:20 -0700 Subject: Re: [PATCH v2] dmaengine: tegra-apb: proper default init of channel slave_id To: Shardar Shariff Md , , , , , , , , , References: <1461329093-20300-1-git-send-email-smohammed@nvidia.com> From: Jon Hunter Message-ID: <571A2A7C.5010305@nvidia.com> Date: Fri, 22 Apr 2016 14:43:24 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: <1461329093-20300-1-git-send-email-smohammed@nvidia.com> X-Originating-IP: [10.21.132.108] X-ClientProxiedBy: UKMAIL102.nvidia.com (10.26.138.15) To UKMAIL101.nvidia.com (10.26.138.13) Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2091 Lines: 62 On 22/04/16 13:44, Shardar Shariff Md wrote: > Initialize default channel slave_id(req_sel) to invalid id > (i.e max supported slave id + 1) to avoid overwriting of slave_id > during tegra_dma_slave_config() with client data if slave_id > is not initialized through DT > > Signed-off-by: Shardar Shariff Md > > --- > - Instead of initializing the slave id to -1 define macros for > max slave id and invalid slave id and do the checks accordingly. > --- > drivers/dma/tegra20-apb-dma.c | 13 +++++++++++-- > 1 file changed, 11 insertions(+), 2 deletions(-) > > diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c > index 3871f29..2957e26 100644 > --- a/drivers/dma/tegra20-apb-dma.c > +++ b/drivers/dma/tegra20-apb-dma.c > @@ -114,6 +114,9 @@ > /* Channel base address offset from APBDMA base address */ > #define TEGRA_APBDMA_CHANNEL_BASE_ADD_OFFSET 0x1000 > > +#define TEGRA_APBDMA_SLAVE_ID_MAX 31 > +#define TEGRA_APBDMA_SLAVE_ID_INVALID (TEGRA_APBDMA_SLAVE_ID_MAX + 1) > + > struct tegra_dma; > > /* > @@ -353,7 +356,7 @@ static int tegra_dma_slave_config(struct dma_chan *dc, > } > > memcpy(&tdc->dma_sconfig, sconfig, sizeof(*sconfig)); > - if (!tdc->slave_id) > + if (tdc->slave_id == TEGRA_APBDMA_SLAVE_ID_INVALID) > tdc->slave_id = sconfig->slave_id; > tdc->config_init = true; > return 0; > @@ -1236,7 +1239,7 @@ static void tegra_dma_free_chan_resources(struct dma_chan *dc) > } > pm_runtime_put(tdma->dev); > > - tdc->slave_id = 0; > + tdc->slave_id = TEGRA_APBDMA_SLAVE_ID_INVALID; > } > > static struct dma_chan *tegra_dma_of_xlate(struct of_phandle_args *dma_spec, > @@ -1253,6 +1256,11 @@ static struct dma_chan *tegra_dma_of_xlate(struct of_phandle_args *dma_spec, > tdc = to_tegra_dma_chan(chan); > tdc->slave_id = dma_spec->args[0]; > > + if (tdc->slave_id > TEGRA_APBDMA_SLAVE_ID_MAX) { > + dev_err(tdc2dev(tdc), "Invalid slave id\n"); > + return NULL; > + } Please move this test to before the dma_get_any_slave_channel(), otherwise we could leak the DMA channel! Cheers Jon