Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751342AbdIOKHn (ORCPT ); Fri, 15 Sep 2017 06:07:43 -0400 Received: from mx08-00178001.pphosted.com ([91.207.212.93]:44825 "EHLO mx07-00178001.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751171AbdIOKHm (ORCPT ); Fri, 15 Sep 2017 06:07:42 -0400 Subject: Re: [PATCH] mtd: spi-nor: stm32-quadspi: Fix uninitialized error return code To: Geert Uytterhoeven CC: Cyrille Pitchen , Marek Vasut , David Woodhouse , Brian Norris , Boris Brezillon , Richard Weinberger , Maxime Coquelin , Alexandre Torgue , Arnd Bergmann , MTD Maling List , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" References: <1500105641-14161-1-git-send-email-geert@linux-m68k.org> <1962615c-d606-2e93-d256-47f15e1b1035@st.com> From: Ludovic BARRE Message-ID: Date: Fri, 15 Sep 2017 12:06:39 +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: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-Originating-IP: [10.75.127.46] X-ClientProxiedBy: SFHDAG4NODE2.st.com (10.75.127.11) To SFHDAG6NODE1.st.com (10.75.127.16) X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-09-15_03:,, signatures=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3543 Lines: 109 On 07/17/2017 12:22 PM, Geert Uytterhoeven wrote: > Hi Ludovic, > > On Mon, Jul 17, 2017 at 11:56 AM, Ludovic BARRE wrote: >> 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 > > Ah, I missed the check for !cmd->tx_data at the top of stm32_qspi_tx() > >> -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 > > If you initialized ret at the beginning, you lose the ability to catch newly > introduced similar bugs in the future. like discuss in thread https://patchwork.kernel.org/patch/9952849/ with Arnd and Geert Cyrille, Marek: could you take geert patch and abandon https://patchwork.kernel.org/patch/9952849/ thanks Acked-by: Ludovic Barre > >> 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, > > Gr{oetje,eeting}s, > > Geert > > -- > Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org > > In personal conversations with technical people, I call myself a hacker. But > when I'm talking to journalists I just say "programmer" or something like that. > -- Linus Torvalds >