From: Alexei Starovoitov <ast@plumgrid.com>
Date: Mon, 1 Dec 2014 23:06:38 +0000 (-0800)
Subject: samples: bpf: trivial eBPF program in C
X-Git-Tag: omap-for-v3.20/drop-legacy-3517~122^2~93^2~1
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a80857822b0c2ed608c93504bd3687b78f20c619;p=pandora-kernel.git

samples: bpf: trivial eBPF program in C

this example does the same task as previous socket example
in assembler, but this one does it in C.

eBPF program in kernel does:
    /* assume that packet is IPv4, load one byte of IP->proto */
    int index = load_byte(skb, ETH_HLEN + offsetof(struct iphdr, protocol));
    long *value;

    value = bpf_map_lookup_elem(&my_map, &index);
    if (value)
        __sync_fetch_and_add(value, 1);

Corresponding user space reads map[tcp], map[udp], map[icmp]
and prints protocol stats every second

Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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