[PATCH] spi: Initialize variable to prevent uninitialized warning

[PATCH] spi: Initialize variable to prevent uninitialized warning

[Nick Krause]

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-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
 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;
 	}
 	cr = bfin_read(&drv_data->regs->ctl) & ~(BIT_CTL_TIMOD | BIT_CTL_WORDSIZE);
-- 
2.0.1

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

[Guenter Roeck]

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-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> ---
>  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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Re: [PATCH] spi: Initialize variable to prevent uninitialized warning

[Mark Brown]

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On Wed, Aug 06, 2014 at 10:22:19PM -0700, Guenter Roeck wrote:

> 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.

It's not.  The goal isn't to fix the warning, it's to fix the problem
the compiler is telling you about - initialising to the wrong value is
just as bad as not being initialised at all.

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