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Date: Fri, 07 Nov 2008 18:49:32 +0100 From: Eric Dumazet <dada1@...mosbay.com> To: Alexey Dobriyan <adobriyan@...il.com> CC: "David S. Miller" <davem@...emloft.net>, Linux Netdev List <netdev@...r.kernel.org>, Patrick McHardy <kaber@...sh.net> Subject: Re: [PATCH] net: introduce read_pnet() and write_pnet() functions Alexey Dobriyan a écrit : > On Fri, Nov 07, 2008 at 04:44:37PM +0100, Eric Dumazet wrote: >> CONFIG_NET_NS is not a widespread option, we can reduce kernel size >> not declaring useless "struct net" pointers in several structures. > > This can be done separatedly for each offending "struct net *". Sure I can split the patch if you think its too complex. I also can leave #ifdef CONFIG_NET_NS all over if you like them. > >> This patch declares three helper to clean various "ifdef CONFIG_NET_NS" >> that we have in many places. > > There is an implicit assumption, that all such ifdefs are bad, while if fact > there are nothing wrong with them: Well... we can hide the ugly details. Especially with #ifdef in C files. > > #ifdef CONFIG_NET_NS > struct net *ct_net; > #endif > >> #ifdef CONFIG_NET_NS >> >> #define DECLARE_PNET(name) struct net *name; > > One more macro, instead of immediately understandable thing. DECLARE_PNET() ? Did you check DECLARE_RWSEM, DECLARE_WAITQUEUE, DECLARE_PER_CPU, DECLARE_BITMAP ... ??? > >> static inline void write_pnet(struct net **pnet, struct net *net) >> { >> *pnet = net; >> } >> >> static inline struct net *read_pnet(struct net * const *pnet) >> { >> return *pnet; >> } >> #else >> >> #define DECLARE_PNET(name) >> #define write_pnet(pnet, net) do { (void)(net);} while (0) >> #define read_pnet(pnet) (&init_net) >> >> #endif >> >> In particular, using these helpers permits a shrink of inet_bind_bucket >> (16 bytes instead of 32 on 32bit arches, and 32 bytes instead of 64 on 64bits) > > Why not just fix exactly bind bucket issue. Another #ifdef ? > > As I posted earlier, ->dst_net can go after IPv6 dst_ops can be embedded > directly into struct netns_ipv6, but header dependencies aren't trivial. > > As for netns comparisons, use net_eq() to amortize the cost somewhat. > > I believe all "struct net*" parameter passing could disappear with appropriate macros. This stuff currently eat a precious register on i386/x86_64/... architectures. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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