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Silva" , Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= , Kishon Vijay Abraham I , Bjorn Helgaas , Christoph Hellwig , Niklas Cassel , dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org, linux-pci@vger.kernel.org, linux-nvme@lists.infradead.org, imx@lists.linux.dev Subject: Re: [PATCH v2 04/11] dmaengine: dw-edma: Remove ll_max = -1 in dw_edma_channel_setup() Message-ID: References: <20260109-edma_ll-v2-0-5c0b27b2c664@nxp.com> <20260109-edma_ll-v2-4-5c0b27b2c664@nxp.com> <6d6c222faypvbo6fvs7tad2gtzxqqzlsjkrbefwmgxodt5thbc@lylpaqxozrg7> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-ClientProxiedBy: PH8P221CA0022.NAMP221.PROD.OUTLOOK.COM (2603:10b6:510:2d8::7) To PA4PR04MB9366.eurprd04.prod.outlook.com (2603:10a6:102:2a9::8) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: PA4PR04MB9366:EE_|PA1PR04MB11263:EE_ X-MS-Office365-Filtering-Correlation-Id: 2d7c4e8d-50a5-4e8c-c5b2-08de754abb58 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|52116014|376014|7416014|366016|19092799006|1800799024|38350700014; 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However, if it occurs, the driver may > > > > overwrite adjacent memory before reporting an error. > > > > > > > > Remove the incorrect assignment so the calculated ll_max is honored > > > > > > > > Fixes: 31fb8c1ff962d ("dmaengine: dw-edma: Improve the linked list and data blocks definition") > > > > Signed-off-by: Frank Li > > > > --- > > > > drivers/dma/dw-edma/dw-edma-core.c | 1 - > > > > 1 file changed, 1 deletion(-) > > > > > > > > diff --git a/drivers/dma/dw-edma/dw-edma-core.c b/drivers/dma/dw-edma/dw-edma-core.c > > > > index c6b014949afe82f10362711fc8a956fe60a72835..b154bdd7f2897d9a28df698a425afc1b1c93698b 100644 > > > > --- a/drivers/dma/dw-edma/dw-edma-core.c > > > > +++ b/drivers/dma/dw-edma/dw-edma-core.c > > > > @@ -770,7 +770,6 @@ static int dw_edma_channel_setup(struct dw_edma *dw, u32 wr_alloc, u32 rd_alloc) > > > > chan->ll_max = (chip->ll_region_wr[chan->id].sz / EDMA_LL_SZ); > > > > else > > > > chan->ll_max = (chip->ll_region_rd[chan->id].sz / EDMA_LL_SZ); > > > > - chan->ll_max -= 1; > > > > > > Just curious: wasn't this to reserve one slot for the final link element? > > > > when calculate avaible entry, always use chan-ll_max -1. ll_max indicate > > memory size, final link element actually occupted a space. > > After the entire series is applied (esp. [PATCH v2 10/11] + [PATCH v2 11/11]), > yes, that makes sense to me. My concern was that before the semantics of > "ll_max" changes, this "-1" was required. In other words, this seemed to me not > a fix but a preparatory patch. Please correct me if I'm misunderstainding. Thanks, I found I make mistake, wrong think it as "chan->ll_max = -1". I will squash this change to patch 10. Frank > > Thanks, > Koichiro > > > > > Frank > > > > > > Best regards, > > > Koichiro > > > > > > > > > > > dev_vdbg(dev, "L. List:\tChannel %s[%u] max_cnt=%u\n", > > > > str_write_read(chan->dir == EDMA_DIR_WRITE), > > > > > > > > -- > > > > 2.34.1 > > > >