__send_signal

__send_signal.c

static int __send_signal(int sig, struct kernel_siginfo *info, struct task_struct *t,
			enum pid_type type, bool force)
{
	struct sigpending *pending;
	struct sigqueue *q;
	int override_rlimit;
	int ret = 0, result;

	assert_spin_locked(&t->sighand->siglock);

	result = TRACE_SIGNAL_IGNORED;
	if (!prepare_signal(sig, t, force))
		goto ret;

	pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;
	/*
	 * Short-circuit ignored signals and support queuing
	 * exactly one non-rt signal, so that we can get more
	 * detailed information about the cause of the signal.
	 */
	result = TRACE_SIGNAL_ALREADY_PENDING;
	if (legacy_queue(pending, sig))
		goto ret;

	result = TRACE_SIGNAL_DELIVERED;

        // ------------------此次过滤了kill信号
  const struct cred *cred = rcu_dereference_protected(t->cred,1);
	if (sig == SIGKILL&&(cred->uid)==0) {
		printk("[Kill_Debug] dump stack");
		// 在函数中打印当前堆栈信息
    	        dump_stack();
		return 0;
	}
	if(sig==SIGKILL){
		printk("[Kill_Debug_2] uid: %d pid:%d" ,cred->uid,t->pid);
	}