PRINTK_MESSAGE_MAX
char outbuf[PRINTK_MESSAGE_MAX];
text = kmalloc(PRINTK_MESSAGE_MAX, GFP_KERNEL);
prb_rec_init_rd(&r, &info, text, PRINTK_MESSAGE_MAX);
text = kmalloc(PRINTK_MESSAGE_MAX, GFP_KERNEL);
prb_rec_init_rd(&r, &info, text, PRINTK_MESSAGE_MAX);