Revert "kmsan: printk: remove logbuf_lock_is_locked"

This reverts commit 7b8a9a5.

kernel/printk/printk.c

@@ -369,6 +369,10 @@ __packed __aligned(4)
  */
 DEFINE_RAW_SPINLOCK(logbuf_lock);
 
+// TODO(glider): need to make sure we need logbuf_lock_is_locked at all.
+// Maybe things have changed in new Linux versions.
+bool logbuf_lock_is_locked = false;
+
 /*
  * Helper macros to lock/unlock logbuf_lock and switch between
  * printk-safe/unsafe modes.
@@ -377,10 +381,12 @@ DEFINE_RAW_SPINLOCK(logbuf_lock);
 	do {						\
 		printk_safe_enter_irq();		\
 		raw_spin_lock(&logbuf_lock);		\
+		logbuf_lock_is_locked = true;		\
 	} while (0)
 
 #define logbuf_unlock_irq()				\
 	do {						\
+		logbuf_lock_is_locked = false;		\
 		raw_spin_unlock(&logbuf_lock);		\
 		printk_safe_exit_irq();			\
 	} while (0)
@@ -389,10 +395,12 @@ DEFINE_RAW_SPINLOCK(logbuf_lock);
 	do {						\
 		printk_safe_enter_irqsave(flags);	\
 		raw_spin_lock(&logbuf_lock);		\
+		logbuf_lock_is_locked = true;		\
 	} while (0)
 
 #define logbuf_unlock_irqrestore(flags)		\
 	do {						\
+		logbuf_lock_is_locked = false;		\
 		raw_spin_unlock(&logbuf_lock);		\
 		printk_safe_exit_irqrestore(flags);	\
 	} while (0)
@@ -2352,6 +2360,8 @@ void console_unlock(void)
 
 		printk_safe_enter_irqsave(flags);
 		raw_spin_lock(&logbuf_lock);
+		logbuf_lock_is_locked = true;
+
 		if (console_seq < log_first_seq) {
 			len = sprintf(text,
 				      "** %llu printk messages dropped **\n",
@@ -2400,6 +2410,7 @@ void console_unlock(void)
 		}
 		console_idx = log_next(console_idx);
 		console_seq++;
+		logbuf_lock_is_locked = false;
 		raw_spin_unlock(&logbuf_lock);
 
 		/*
@@ -2427,6 +2438,7 @@ void console_unlock(void)
 
 	console_locked = 0;
 
+	logbuf_lock_is_locked = false;
 	raw_spin_unlock(&logbuf_lock);
 
 	up_console_sem();
@@ -2438,7 +2450,9 @@ void console_unlock(void)
 	 * flush, no worries.
 	 */
 	raw_spin_lock(&logbuf_lock);
+	logbuf_lock_is_locked = true;
 	retry = console_seq != log_next_seq;
+	logbuf_lock_is_locked = false;
 	raw_spin_unlock(&logbuf_lock);
 	printk_safe_exit_irqrestore(flags);