From mboxrd@z Thu Jan  1 00:00:00 1970
From: =?ISO-8859-2?Q?Micha=B3_Miros=B3aw?= <mirqus@gmail.com>
Subject: Re: [PATCH 2/2] net: Handle different key sizes between address
 families in flow cache
Date: Sun, 4 Sep 2011 17:34:19 +0200
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References: <alpine.LFD.2.00.1109031004500.1492@ja.ssi.bg> <1315141641-3120-3-git-send-email-david.ward@ll.mit.edu>
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Cc: netdev@vger.kernel.org, Julian Anastasov <ja@ssi.bg>
To: David Ward <david.ward@ll.mit.edu>
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2011/9/4 David Ward <david.ward@ll.mit.edu>:
> With the conversion of struct flowi to a union of AF-specific structs=
, some
> operations on the flow cache need to account for the exact size of th=
e key.
[...]
> --- a/include/net/flow.h
> +++ b/include/net/flow.h
[...]
> +typedef unsigned long flow_compare_t;
> +
> +static inline size_t flowi_size(u16 family)
> +{
> + =A0 =A0 =A0 switch (family) {
> + =A0 =A0 =A0 case AF_INET:
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 BUILD_BUG_ON(sizeof(struct flowi4) % si=
zeof(flow_compare_t));
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 return sizeof(struct flowi4);
> + =A0 =A0 =A0 case AF_INET6:
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 BUILD_BUG_ON(sizeof(struct flowi6) % si=
zeof(flow_compare_t));
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 return sizeof(struct flowi6);
> + =A0 =A0 =A0 case AF_DECnet:
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 BUILD_BUG_ON(sizeof(struct flowidn) % s=
izeof(flow_compare_t));
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 return sizeof(struct flowidn);
> + =A0 =A0 =A0 }
> + =A0 =A0 =A0 return 0;
> +}

Since most called user (flow_key_compare) uses returned value didided
by sizeof(flow_compare_t), you could just return divided value here
and save some shift operations by it.

Best Regards,
Micha=B3 Miros=B3aw