RE: [PATCH 3.12 065/122] lib/checksum.c: fix carry in csum_tcpudp_nofold

[David Laight]

> +static inline u32 from64to32(u64 x)
> +{
> +	/* add up 32-bit and 32-bit for 32+c bit */
> +	x = (x & 0xffffffff) + (x >> 32);
> +	/* add up carry.. */
> +	x = (x & 0xffffffff) + (x >> 32);
> +	return (u32)x;
> +}

As a matter of interest, does the compiler optimise away the
second (x & 0xffffffff) ?
The code could just be:
	x = (x & 0xffffffff) + (x >> 32);
	return x + (x >> 32);

	David

	
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