linux-kernel - Re: [PATCH] net: sfc: avoid -Wtype-limits warning

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Message-ID: <3f85b364-6913-1ed5-0bc0-19aa2edc59f6@solarflare.com>
Date:	Thu, 16 Jun 2016 11:31:52 +0100
From:	Bert Kenward <bkenward@...arflare.com>
To:	Arnd Bergmann <arnd@...db.de>,
	Solarflare linux maintainers <linux-net-drivers@...arflare.com>,
	Edward Cree <ecree@...arflare.com>
CC:	"David S. Miller" <davem@...emloft.net>,
	Martin Habets <mhabets@...arflare.com>,
	<netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] net: sfc: avoid -Wtype-limits warning

On 15/06/16 21:31, Arnd Bergmann wrote:
> When building with -Wextra, we get a harmless warning from the
> EFX_EXTRACT_OWORD32 macro:
> 
> ethernet/sfc/farch.c: In function 'efx_farch_test_registers':
> ethernet/sfc/farch.c:119:30: error: comparison of unsigned expression < 0 is always false [-Werror=type-limits]
> ethernet/sfc/farch.c:124:144: error: comparison of unsigned expression < 0 is always false [-Werror=type-limits]
> ethernet/sfc/farch.c:124:392: error: comparison of unsigned expression < 0 is always false [-Werror=type-limits]
> ethernet/sfc/farch.c:124:731: error: comparison of unsigned expression < 0 is always false [-Werror=type-limits]
> 
> The macro and the caller are both correct, but we can avoid the
> warning by changing the index variable to a signed type.
> 
> Signed-off-by: Arnd Bergmann <arnd@...db.de>

Acked-by: Bert Kenward <bkenward@...arflare.com>

> ---
>  drivers/net/ethernet/sfc/farch.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/sfc/farch.c b/drivers/net/ethernet/sfc/farch.c
> index 133e9e35be9e..4c83739d158f 100644
> --- a/drivers/net/ethernet/sfc/farch.c
> +++ b/drivers/net/ethernet/sfc/farch.c
> @@ -104,7 +104,8 @@ int efx_farch_test_registers(struct efx_nic *efx,
>  			     const struct efx_farch_register_test *regs,
>  			     size_t n_regs)
>  {
> -	unsigned address = 0, i, j;
> +	unsigned address = 0;
> +	int i, j;
>  	efx_oword_t mask, imask, original, reg, buf;
>  
>  	for (i = 0; i < n_regs; ++i) {
>