Linux kernel _RET_IP_ and _THIS_IP_

#define _RET_IP_        (unsigned long)__builtin_return_address(0)
#define _THIS_IP_  ({ __label__ __here; __here: (unsigned long)&&__here; })


可以通过它来打印调用栈, addr参数传入_RET_IP

static void print_track(const char *s, struct track *t)
{
    if (!t->addr)
        return;


    printk(KERN_ERR "INFO: %s in %pS age=%lu cpu=%u pid=%d\n",
        s, (void *)t->addr, jiffies - t->when, t->cpu, t->pid);
#ifdef CONFIG_STACKTRACE
    {    
        int i;
        for (i = 0; i < TRACK_ADDRS_COUNT; i++) 
            if (t->addrs[i])
                printk(KERN_ERR "\t%pS\n", (void *)t->addrs[i]);
            else 
                break;
    }    
#endif
}


Following copy from http://blog.chinaunix.net/uid-11455994-id-176451.html

— Built-in Function: void * __builtin_return_address (unsigned int level)

This function returns the return address of the current function, or of one of its callers. The level argument is number of frames to scan up the call stack. A value of 0 yields the return address of the current function, a value of 1 yields the return address of the caller of the current function, and so forth. When inlining the expected behavior is that the function will return the address of the function that will be returned to. To work around this behavior use the noinline function attribute. 

Refer to:

http://blog.chinaunix.net/u/12592/showart_1679862.html