Date: Mon, 20 Apr 2015 19:52:33 +0000 From: Mark Johnston <markj@FreeBSD.org> To: Gleb Smirnoff <glebius@FreeBSD.org> Cc: freebsd-net@FreeBSD.org Subject: Re: moving struct bpf_if to bpf.c Message-ID: <20150420195233.GA71166@muskytusk> In-Reply-To: <20150420192618.GY883@FreeBSD.org> References: <20150418210855.GA50409@charmander.west.isilon.com> <20150420192618.GY883@FreeBSD.org>
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On Mon, Apr 20, 2015 at 10:26:18PM +0300, Gleb Smirnoff wrote: > On Sat, Apr 18, 2015 at 02:08:56PM -0700, Mark Johnston wrote: > M> At the moment, bpf.h defines struct bpf_if differently depending on > M> whether BPF_INTERNAL is #defined. This causes problems with CTF, as it > M> results in a sort of bifurcation within the type graph: CTF sees two > M> different struct bpf_ifs, and so every struct/union containing a struct > M> bpf_if is duplicated, and so on. CTF currently imposes a limit of 2^15 > M> distinct types within a container, and several people have been running > M> into this limit. The type duplication exacerbates this problem. > M> > M> The change here fixes the issue by moving the definition of > M> struct bpf_if to bpf.c, and making its externally-used fields > M> available via struct bpf_if_ext: https://reviews.freebsd.org/D2319 > M> > M> In particular, the ext fields are at the same offsets within struct > M> bpf_if as before, so this change should have no functional impact. > M> Moreover, it reduces the number of types from 20879 to 15725 with my > M> (stripped-down) kernel config on amd64. Would anyone be willing to > M> review the proposed change? I've also placed the raw diff here: > M> https://people.freebsd.org/~markj/patches/bpf_entrails.diff > > What actual software needs to look at struct bpf_if? I wonder if > we can fix the software and hide the struct bpf_if into kernel > entirely. bpf_peers_present() is defined in bpf.h so that it can be inlined, and it needs access to the bif_dlist field of struct bpf_if. As far as I can see, this is the only reason for exposing part of struct bpf_if.
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