Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751971AbdINMj4 (ORCPT ); Thu, 14 Sep 2017 08:39:56 -0400 Received: from mx07-00178001.pphosted.com ([62.209.51.94]:38347 "EHLO mx07-00178001.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751618AbdINMjz (ORCPT ); Thu, 14 Sep 2017 08:39:55 -0400 Subject: Re: [PATCH] mtd: spi-nor: stm32-quadspi: avoid unintialized return code To: Arnd Bergmann , Cyrille Pitchen , Marek Vasut CC: David Woodhouse , Brian Norris , Boris Brezillon , Richard Weinberger , Maxime Coquelin , Alexandre Torgue , , , References: <20170914110709.3591691-1-arnd@arndb.de> From: Ludovic BARRE Message-ID: Date: Thu, 14 Sep 2017 14:38:51 +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: <20170914110709.3591691-1-arnd@arndb.de> 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: SFHDAG1NODE1.st.com (10.75.127.1) To SFHDAG6NODE1.st.com (10.75.127.16) X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-09-14_03:,, signatures=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1612 Lines: 48 hi Arnd thx Arnd for compilation warning (gcc <= 4.6) Acked-by: Ludovic Barre PS: at runtime stm32_qspi_tx_poll can't be call, because stm32_qspi_tx check if there is tx data available if (!cmd->tx_data) return 0; BR Ludo On 09/14/2017 01:06 PM, Arnd Bergmann wrote: > If we send zero-length data to stm32_qspi_tx_poll() on older > compiler versions such as gcc-4.6, we get warned that the > return code is uninitialized: > > drivers/mtd/spi-nor/stm32-quadspi.c:248:2: error: ‘ret’ may be used uninitialized in this function [-Werror=uninitialized] > > On newer compiler versions, the return code is always zero > in this case, as the local variable gets optimized away and > is assumed to be zero after the loop completes without error. > > This changes the function to instead return -EINVAL if it > ever gets called with a zero length buffer. > > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82203 > Signed-off-by: Arnd Bergmann > --- > drivers/mtd/spi-nor/stm32-quadspi.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/mtd/spi-nor/stm32-quadspi.c b/drivers/mtd/spi-nor/stm32-quadspi.c > index 86c0931543c5..711cfe7aa4bf 100644 > --- a/drivers/mtd/spi-nor/stm32-quadspi.c > +++ b/drivers/mtd/spi-nor/stm32-quadspi.c > @@ -227,7 +227,7 @@ static int stm32_qspi_tx_poll(struct stm32_qspi *qspi, > void (*tx_fifo)(u8 *, void __iomem *); > u32 len = cmd->len, sr; > u8 *buf = cmd->buf; > - int ret; > + int ret = -EINVAL; > > if (cmd->qspimode == CCR_FMODE_INDW) > tx_fifo = stm32_qspi_write_fifo; >