signal: check sig before setting info in kill_pid_usb_asyncio

In kill_pid_usb_asyncio, if signal is not valid, we do not need to
set info struct.

Signed-off-by: Zhiqiang Liu <liuzhiqiang26@huawei.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Link: https://lore.kernel.org/r/f525fd08-1cf7-fb09-d20c-4359145eb940@huawei.com
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

kernel/signal.c

@@ -1510,15 +1510,15 @@ int kill_pid_usb_asyncio(int sig, int errno, sigval_t addr,
 	unsigned long flags;
 	int ret = -EINVAL;
 
+	if (!valid_signal(sig))
+		return ret;
+
 	clear_siginfo(&info);
 	info.si_signo = sig;
 	info.si_errno = errno;
 	info.si_code = SI_ASYNCIO;
 	*((sigval_t *)&info.si_pid) = addr;
 
-	if (!valid_signal(sig))
-		return ret;
-
 	rcu_read_lock();
 	p = pid_task(pid, PIDTYPE_PID);
 	if (!p) {