[PATCH v2] Merge ipt_LOG and ip6t_LOG, add ring bufffer support

Hi!

This patch set merges ipt_LOG and ip6t_LOG and adds ring buffer support
to xt_LOG.

Using "--ring" a user can create LOG rules which log messages into
one or more ring buffers.
Each ring buffer is represented as pipe-like file in
/proc/net/netfilter/xt_LOG_ring/.

Ring buffer support can be enabled/disabled using
CONFIG_NETFILTER_XT_TARGET_LOG_RING.

Changes since v1:
 - Merged ipt_LOG and ip6t_LOG
 - Implemented ring buffer support as part of xt_LOG.

[PATCH 1/6] Netfilter: Merge ipt_LOG and ip6_LOG into xt_LOG
[PATCH 2/6] ring_buffer: Export for_each_buffer_cpu()
[PATCH 3/6] xt_log: Make printk() in sb_close() optional
[PATCH 4/6] Netfilter: xt_LOG: Implement ring buffer support
[PATCH 5/6] iptables: Merge libip6t_LOG and libipt_LOG into
[PATCH 6/6] iptables: xt_LOG: Add ring buffer support

Any feedback is welcome!

Thanks,
//richard