Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751406AbdGQJ52 (ORCPT ); Mon, 17 Jul 2017 05:57:28 -0400 Received: from mx08-00178001.pphosted.com ([91.207.212.93]:48689 "EHLO mx07-00178001.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751313AbdGQJ5W (ORCPT ); Mon, 17 Jul 2017 05:57:22 -0400 Subject: Re: [PATCH] mtd: spi-nor: stm32-quadspi: Fix uninitialized error return code To: Geert Uytterhoeven , Cyrille Pitchen , Marek Vasut , David Woodhouse , Brian Norris , Boris Brezillon , Richard Weinberger , Maxime Coquelin , Alexandre Torgue CC: Arnd Bergmann , , , References: <1500105641-14161-1-git-send-email-geert@linux-m68k.org> From: Ludovic BARRE Message-ID: <1962615c-d606-2e93-d256-47f15e1b1035@st.com> Date: Mon, 17 Jul 2017 11:56:13 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: <1500105641-14161-1-git-send-email-geert@linux-m68k.org> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Originating-IP: [10.75.127.50] X-ClientProxiedBy: SFHDAG6NODE1.st.com (10.75.127.16) To SFHDAG6NODE1.st.com (10.75.127.16) X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-07-17_06:,, signatures=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2337 Lines: 80 Hi Geert Thanks for your remarks. Today only write_reg could be call with len=0 (spi-nor.c: write_enable/disable, set_4byte, erase_chip) But your remark make sense to prevent: gcc warning and framework evolution ... -In stm32-quadspi.c transfer data is enabled if tx_data is true (some actions under this bool) stm32_qspi_write_reg has already this protection with "!!(buf && len > 0);" but we could extend this protection - cmd.tx_data = true; + cmd.tx_data = !!(len > 0); In : stm32_qspi_read, stm32_qspi_write, stm32_qspi_read_reg -And to avoid gcc warning: I prefer initialize "ret" in the beginning of function - int ret; + int ret = 0; I tested this changes, and it's ok for me. Geert could you resend a new version, or do you prefer that I take care of it BR Ludo On 07/15/2017 10:00 AM, Geert Uytterhoeven wrote: > With gcc 4.1.2: > > drivers/mtd/spi-nor/stm32-quadspi.c: In function ‘stm32_qspi_tx_poll’: > drivers/mtd/spi-nor/stm32-quadspi.c:230: warning: ‘ret’ may be used uninitialized in this function > > Indeed, if stm32_qspi_cmd.len is zero, ret will be uninitialized. > This length is passed from outside the driver using the > spi_nor.{read,write}{,_reg}() callbacks. > > Several functions in drivers/mtd/spi-nor/spi-nor.c (e.g. write_enable(), > write_disable(), and erase_chip()) call spi_nor.write_reg() with a zero > length. > > Fix this by returning an explicit zero on success. > > Fixes: 0d43d7ab277a048c ("mtd: spi-nor: add driver for STM32 quad spi flash controller") > Signed-off-by: Geert Uytterhoeven > --- > drivers/mtd/spi-nor/stm32-quadspi.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/mtd/spi-nor/stm32-quadspi.c b/drivers/mtd/spi-nor/stm32-quadspi.c > index 86c0931543c538c3..ad6a3e1844cbe5ec 100644 > --- a/drivers/mtd/spi-nor/stm32-quadspi.c > +++ b/drivers/mtd/spi-nor/stm32-quadspi.c > @@ -240,12 +240,12 @@ static int stm32_qspi_tx_poll(struct stm32_qspi *qspi, > STM32_QSPI_FIFO_TIMEOUT_US); > if (ret) { > dev_err(qspi->dev, "fifo timeout (stat:%#x)\n", sr); > - break; > + return ret; > } > tx_fifo(buf++, qspi->io_base + QUADSPI_DR); > } > > - return ret; > + return 0; > } > > static int stm32_qspi_tx_mm(struct stm32_qspi *qspi,