Messages in this thread | | | Date | Sat, 14 Mar 2015 19:02:57 -0700 | From | Alexei Starovoitov <> | Subject | Re: [PATCH v2 net-next 1/2] bpf: allow extended BPF programs access skb fields |
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On 3/14/15 4:51 PM, Daniel Borkmann wrote: > On 03/14/2015 04:55 PM, Alexei Starovoitov wrote: > ... >> so from there I saw two options: either copy paste all >> build_bug_on and have the same *insn=... and build_bug_on in >> two places or consolidate them in single helper function. >> Obviously single helper function is a preferred method. >> I'm not sure what are you still arguing about. > > I'm repeating myself here, but fair enough. To me the v1 > code in sk_filter_convert_ctx_access() was more sound. So > taking out the ifindex issue, that's 4 BUILD_BUG_ON()s in > addition.
correct. it's 4 build_bug_on to several lines of copy pasted code. That copy-paste between two functions was already bugging me when I posted v1, but back then I didn't see a way to create a common helper. Adding this 4 extra lines pushed it over my internal bar of 'acceptable' copied code :) so in v2 I figured a way to create a helper.
> I actually think the current filter code is in a reasonable > shape. convert_bpf_extensions() is full of BPF to eBPF > conversions, so going over convert_bpf_extensions() some of > them would now use convert_skb_access(), some other ``skb > accesses''use macros directly in place, the reading-flow of > this code now is inconsistent to me and it would have been > more sound if that's just left as is in convert_bpf_extensions().
I still don't see this 'inconsistency'. convert_bpf_extensions() has code to convert classic only accesses. convert_skb_access() has code to convert both classic and extended. sk_filter_convert_ctx_access() has code to convert extended only.
In this patch convert_skb_access() has to deal with 3 fields. Later we may allow more field to be accessed by extended, so more lines will simply move from convert_bpf_extensions() into convert_skb_access(). So it will save us from copy-pasting in the future.
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