[PATCH] ip_conntrack_ftp: improve performance of update_nl_seq

[高昌利]

[NETFILTER]: nf_conntrack_ftp: Improve the performance of update_nl_seq by using
temporary variables and changing the sequence of program.

----
Signed-off-by: xiaosuo <xiaosuo at gmail.com>
----
 ip_conntrack_ftp.c |   31 +++++++++++++++++--------------
 1 file changed, 17 insertions(+), 14 deletions(-)
----
--- linux/net/ipv4/netfilter/ip_conntrack_ftp.c 2007-05-28 21:59:22.000000000
+0800
+++ linux-new/net/ipv4/netfilter/ip_conntrack_ftp.c     2007-05-28
22:36:07.000000000 +0800
@@ -264,25 +264,28 @@
 static void update_nl_seq(u32 nl_seq, struct ip_ct_ftp_master *info, int dir,
                          struct sk_buff *skb)
 {
-       unsigned int i, oldest = NUM_SEQ_TO_REMEMBER;
+       unsigned int i, oldest;
+       u_int32_t *seq_aft_nl = info->seq_aft_nl[dir];
+       int seq_aft_nl_num = info->seq_aft_nl_num[dir];

-       /* Look for oldest: if we find exact match, we're done. */
-       for (i = 0; i < info->seq_aft_nl_num[dir]; i++) {
-               if (info->seq_aft_nl[dir][i] == nl_seq)
-                       return;
+       if (seq_aft_nl_num < NUM_SEQ_TO_REMEMBER) {
+               seq_aft_nl[info->seq_aft_nl_num[dir]++] = nl_seq;
+               ip_conntrack_event_cache(IPCT_HELPINFO_VOLATILE, skb);
+               return;
+       }

-               if (oldest == info->seq_aft_nl_num[dir]
-                   || before(info->seq_aft_nl[dir][i], oldest))
+       for (oldest = 0, i = 1; i < seq_aft_nl_num; i ++) {
+               if (seq_aft_nl[oldest] == nl_seq)
+                       return;
+               if (before(seq_aft_nl[i], seq_aft_nl[oldest]))
                        oldest = i;
        }

-       if (info->seq_aft_nl_num[dir] < NUM_SEQ_TO_REMEMBER) {
-               info->seq_aft_nl[dir][info->seq_aft_nl_num[dir]++] = nl_seq;
-               ip_conntrack_event_cache(IPCT_HELPINFO_VOLATILE, skb);
-       } else if (oldest != NUM_SEQ_TO_REMEMBER) {
-               info->seq_aft_nl[dir][oldest] = nl_seq;
-               ip_conntrack_event_cache(IPCT_HELPINFO_VOLATILE, skb);
-       }
+       if (nl_seq == seq_aft_nl[oldest] || before(nl_seq, seq_aft_nl[oldest]))
+               return;
+
+       seq_aft_nl[oldest] = nl_seq;
+       ip_conntrack_event_cache(IPCT_HELPINFO_VOLATILE, skb);
 }

 static int help(struct sk_buff **pskb,


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