linux-kernel - [PATCH] mtd: spi-nor: stm32-quadspi: Fix uninitialized error return code

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Date:   Sat, 15 Jul 2017 10:00:41 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Ludovic Barre <ludovic.barre@...com>,
        Cyrille Pitchen <cyrille.pitchen@...ev4u.fr>,
        Marek Vasut <marek.vasut@...il.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Boris Brezillon <boris.brezillon@...e-electrons.com>,
        Richard Weinberger <richard@....at>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...com>
Cc:     Arnd Bergmann <arnd@...db.de>, linux-mtd@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Geert Uytterhoeven <geert@...ux-m68k.org>
Subject: [PATCH] mtd: spi-nor: stm32-quadspi: Fix uninitialized error return code

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 <geert@...ux-m68k.org>
---
 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,
-- 
2.7.4