系统日志 time wait、__ratelimit、 SYN flooding含义

'net_ratelimit()

___ratelimit()

int ___ratelimit(struct ratelimit_state *rs, const char *func)
{
unsigned long flags;
31         int ret;
32
33         if (!rs->interval)
34                 return 1;
35
36         /*
37          * If we contend on this state's lock then almost
38          * by definition we are too busy to print a message,
39          * in addition to the one that will be printed by
40          * the entity that is holding the lock already:
41          */
42         if (!raw_spin_trylock_irqsave(&rs->lock, flags))
43                 return 0;
44
45         if (!rs->begin)
46                 rs->begin = jiffies;
47
48         if (time_is_before_jiffies(rs->begin + rs->interval)) {
49                 if (rs->missed)
50                         printk(KERN_WARNING "%s: %d callbacks suppressed\n",
51                                 func, rs->missed);
52                 rs->begin   = 0;
53                 rs->printed = 0;
54                 rs->missed  = 0;
55         }