LXR linux/include/net/netfilter/xt

   1#define S_SIZE (1024 - (sizeof(unsigned int) + 1))
   2
   3struct sbuff {
   4        unsigned int    count;
   5        char            buf[S_SIZE + 1];
   6};
   7static struct sbuff emergency, *emergency_ptr = &emergency;
   8
   9static __printf(2, 3) int sb_add(struct sbuff *m, const char *f, ...)
  10{
  11        va_list args;
  12        int len;
  13
  14        if (likely(m->count < S_SIZE)) {
  15                va_start(args, f);
  16                len = vsnprintf(m->buf + m->count, S_SIZE - m->count, f, args);
  17                va_end(args);
  18                if (likely(m->count + len < S_SIZE)) {
  19                        m->count += len;
  20                        return 0;
  21                }
  22        }
  23        m->count = S_SIZE;
  24        printk_once(KERN_ERR KBUILD_MODNAME " please increase S_SIZE\n");
  25        return -1;
  26}
  27
  28static struct sbuff *sb_open(void)
  29{
  30        struct sbuff *m = kmalloc(sizeof(*m), GFP_ATOMIC);
  31
  32        if (unlikely(!m)) {
  33                local_bh_disable();
  34                do {
  35                        m = xchg(&emergency_ptr, NULL);
  36                } while (!m);
  37        }
  38        m->count = 0;
  39        return m;
  40}
  41
  42static void sb_close(struct sbuff *m)
  43{
  44        m->buf[m->count] = 0;
  45        printk("%s\n", m->buf);
  46
  47        if (likely(m != &emergency))
  48                kfree(m);
  49        else {
  50                emergency_ptr = m;
  51                local_bh_enable();
  52        }
  53}
  54
  55