linux-kernel - Re: [PATCH] spi: Initialize variable to prevent uninitialized warning

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Date:	Wed, 6 Aug 2014 22:22:19 -0700
From:	Guenter Roeck <linux@...ck-us.net>
To:	Nick Krause <xerofoiify@...il.com>
Cc:	Mark Brown <broonie@...nel.org>,
	"open list:SPI SUBSYSTEM" <linux-spi@...r.kernel.org>,
	open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] spi: Initialize variable to prevent uninitialized warning

On Thu, Aug 07, 2014 at 06:51:00AM +0200, Nick Krause wrote:
> While compiling we see the following waring
> 
> drivers/spi/spi-bfin5xx.c: In function 'bfin_spi_pump_transfers':
> drivers/spi/spi-bfin5xx.c:695:6: warning: 'cr_width' may be used uninitialized
> in this function [-Wuninitialized]
> 
> Initialize it to prevent the above warning
> 
> Signed-off-by: Nick Krause <xerofoify@...il.com>
> ---
>  drivers/spi/spi-bfin5xx.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/spi/spi-bfin5xx.c b/drivers/spi/spi-bfin5xx.c
> index ebf720b..f268bf4 100644
> --- a/drivers/spi/spi-bfin5xx.c
> +++ b/drivers/spi/spi-bfin5xx.c
> @@ -559,7 +559,7 @@ static void bfin_spi_pump_transfers(unsigned long data)
>  	struct spi_transfer *previous = NULL;
>  	struct bfin_spi_slave_data *chip = NULL;
>  	unsigned int bits_per_word;
> -	u16 cr, cr_width, dma_width, dma_config;
> +	u16 cr, cr_width = 0, dma_width, dma_config;
>  	u32 tranf_success = 1;
>  	u8 full_duplex = 0;
>  
> @@ -648,7 +648,6 @@ static void bfin_spi_pump_transfers(unsigned long data)
>  	} else if (bits_per_word == 8) {
>  		drv_data->n_bytes = bits_per_word/8;
>  		drv_data->len = transfer->len;
> -		cr_width = 0;
>  		drv_data->ops = &bfin_bfin_spi_transfer_ops_u8;
>  	}

So if we ever hit that uninitialized case, where bits_per_word is
neither 8 nor 16, we'll have ops set to NULL and end up wondering
why the kernel crashes a bit further down in the code. Not really
sure if that is an improvement.

Guenter
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