printk: only look for prefix levels in kernel messages

vprintk_emit() prefix parsing should only be done for internal kernel
messages.  This allows existing behavior to be kept in all cases.
Signed-off-by: Joe Perches <joe@perches.com>
Cc: Kay Sievers <kay@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/printk.c

@@ -1487,7 +1487,6 @@ asmlinkage int vprintk_emit(int facility, int level,
 	size_t text_len;
 	enum log_flags lflags = 0;
 	unsigned long flags;
-	int kern_level;
 	int this_cpu;
 	int printed_len = 0;
 
@@ -1543,8 +1542,10 @@ asmlinkage int vprintk_emit(int facility, int level,
 		lflags |= LOG_NEWLINE;
 	}
 
-	/* strip syslog prefix and extract log level or control flags */
-	kern_level = printk_get_level(text);
+	/* strip kernel syslog prefix and extract log level or control flags */
+	if (facility == 0) {
+		int kern_level = printk_get_level(text);
+
 		if (kern_level) {
 			const char *end_of_header = printk_skip_level(text);
 			switch (kern_level) {
@@ -1559,6 +1560,7 @@ asmlinkage int vprintk_emit(int facility, int level,
 			text_len -= end_of_header - text;
 			text = (char *)end_of_header;
 		}
+	}
 
 	if (level == -1)
 		level = default_message_loglevel;