Alexey Dobriyan wrote: > On Thu, Feb 11, 2010 at 11:27 AM, Patrick McHardy <kaber@xxxxxxxxx> wrote: >> Alexey Dobriyan wrote: >>>> -static inline int ebt_basic_match(struct ebt_entry *e, struct ethhdr *h, >>>> - const struct net_device *in, const struct net_device *out) >>>> +static inline int >>>> +ebt_basic_match(const struct ebt_entry *e, const struct ethhdr *h, >>>> + const struct net_device *in, const struct net_device *out) >>> These const modifiers are pointless because compilers are smart enough >>> to notice non-modifiability and generate the very same code in both cases. >>> >>> Nowadays, half of functions declarations in generic >>> xtables/iptables/ip6tables/arptables >>> code are littered with const which makes them pretty unpleasant to read. >> Well, the benefit is that the compiler can catch accidental modification >> of data that is supposed to be constant. > > Did it ever? Realistically? Yes, occasionally it has caught typos or other variable mixups for me. It also documents that a variable is only supposed to be read. >>From what I see, const is used with string functions > (to make string literals go to rodata) and with structures full of hooks > (to make them go to rodata). Yes, that's also a reason. >>>> - struct ebt_entry *e = (struct ebt_entry *)chain->data; >>>> + const struct ebt_entry *e = (struct ebt_entry *)chain->data; >>> And such things are wrong (not second const). >> What's wrong about this? > > Should it be (const struct ebt_entry *)? That's not necessary. Its just declaring the the memory should not be modified through e. The const qualification happens automatically. -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
