ipmi_watchdog: Fix read syscall not responding to signals during sleep

Read syscall cannot response to sigals when data_to_read remains at 0
and the while loop cannot break.  Check signal_pending in the loop.

Reported-by: Zhen Ni <zhen.ni@easystack.cn>
Message-Id: <20230517085412.367022-1-zhen.ni@easystack.cn>
Signed-off-by: Corey Minyard <minyard@acm.org>

Author: cminyard

drivers/char/ipmi/ipmi_watchdog.c

@@ -802,7 +802,7 @@ static ssize_t ipmi_read(struct file *file,
 
 		init_waitqueue_entry(&wait, current);
 		add_wait_queue(&read_q, &wait);
-		while (!data_to_read) {
+		while (!data_to_read && !signal_pending(current)) {
 			set_current_state(TASK_INTERRUPTIBLE);
 			spin_unlock_irq(&ipmi_read_lock);
 			schedule();