Messages in this thread | | | Date | Fri, 14 Mar 2014 13:58:22 +0100 | From | Pablo Neira Ayuso <> | Subject | Re: [PATCH v10 net-next 1/3] filter: add Extended BPF interpreter and converter |
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On Wed, Mar 12, 2014 at 02:43:32PM -0700, Alexei Starovoitov wrote: > diff --git a/include/linux/filter.h b/include/linux/filter.h > index e568c8ef896b..6e6aab5e062b 100644 > --- a/include/linux/filter.h > +++ b/include/linux/filter.h > @@ -25,20 +25,45 @@ struct sock; > struct sk_filter > { > atomic_t refcnt; > - unsigned int len; /* Number of filter blocks */ > + /* len - number of insns in sock_filter program > + * len_ext - number of insns in socket_filter_ext program > + * jited - true if either original or extended program was JITed > + * orig_prog - original sock_filter program if not NULL > + */ > + unsigned int len; > + unsigned int len_ext; > + unsigned int jited:1;
This is consuming 4 bytes just to store the jited bit. I think you can scratch that bit from len, given the maximum filter length for bpf. I think the the jited bit change that David suggested have to come in first place as a separated patch in the series.
> + struct sock_filter *orig_prog;
If your new extended filtering is not used, this consumes 8 extra bytes + len_ext (bytes) in x86_64. I think a more generic way to make this is that you can move the original bpf filter and its length at the bottom of this structure after insns to store something like:
struct sk_bpf_compat { struct sock_filter *prog; unsigned int len; };
This would be only allocated when you filtering approach is used. For that you'll need some enum in sk_filter to indicate the filtering approach, but we'll save 8 bytes per filter in the end with regards to this current patch.
> struct rcu_head rcu; > - unsigned int (*bpf_func)(const struct sk_buff *skb, > - const struct sock_filter *filter); > + union { > + unsigned int (*bpf_func)(const struct sk_buff *skb, > + const struct sock_filter *fp); > + unsigned int (*bpf_func_ext)(const struct sk_buff *skb, > + const struct sock_filter_ext *fp); > + }; > union { > struct sock_filter insns[0]; > + struct sock_filter_ext insns_ext[0]; > struct work_struct work; > }; > }; >
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