On 09/22/2015 03:55 PM, David Ahern wrote:
ip_route_input_slow is a maze of gotos (9 of them!) making it error prone and difficult to read. This patchset refactors it, removing all but 2 of the labels. The brd_input label for broadcast path requires too many inputs to make a reasonble helper out of it so I left it as is.None of these patches change functionality, only move code around to make ip_route_input_slow more readable. Size comparison using gcc version 4.7.2 (Debian 4.7.2-5) With CONFIG_IP_ROUTE_VERBOSE: Before patches: $ size kbuild2/net/ipv4/route.o text data bss dec hex filename 20615 2321 32 22968 59b8 kbuild2/net/ipv4/route.o After patches: $ size kbuild/net/ipv4/route.o text data bss dec hex filename 20774 2321 32 23127 5a57 kbuild/net/ipv4/route.o An increase of 159 bytes with CONFIG_IP_ROUTE_VERBOSE. Without CONFIG_IP_ROUTE_VERBOSE: Before patches: $ size kbuild2/net/ipv4/route.o text data bss dec hex filename 19778 2321 32 22131 5673 kbuild2/net/ipv4/route.o After patches: $ size kbuild/net/ipv4/route.o text data bss dec hex filename 19858 2321 32 22211 56c3 kbuild/net/ipv4/route.o An increase of 80 bytes without CONFIG_IP_ROUTE_VERBOSE. David Ahern (9): net: Remove martian_source_keep_err goto label net: Remove e_inval label from ip_route_input_slow net: Remove e_nobufs label from ip_route_input_slow net: Move rth handling from ip_route_input_slow to helper net: Move martian_destination to helper net: Remove martian_source goto net: Remove martian_destination label net: Remove local_input label net: Remove no_route label net/ipv4/route.c | 239 ++++++++++++++++++++++++++++++++----------------------- 1 file changed, 139 insertions(+), 100 deletions(-)
One option you might consider when untangling this is to just return the values instead of leaving any labels. I just did a quick test on my system with gcc version 5.1.1 and going through and just replacing all of the labels with returns actually resulted in smaller code since the compiler was smart enough to just combine the returns anyway.
You may also want to increase the scope of this patch set to include __mkroute_input as it ends up being compiled into this function as well. From what I have seen there is a bit of redundancy with some of the code from local_input.
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