early_printk: Allow more than one early console

It is desirable to be able to use one early boot device to debug
another or to have multiple places you can see the early boot
diagnostics, such as the vga screen or serial device.

This patch changes the early_printk console device registration to
allow more than one early printk device to get registered via
register_console().
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

arch/x86/kernel/early_printk.c

@@ -176,10 +176,19 @@ asmlinkage void early_printk(const char *fmt, ...)
 	va_end(ap);
 }
 
+static inline void early_console_register(struct console *con, int keep_early)
+{
+	early_console = con;
+	if (keep_early)
+		early_console->flags &= ~CON_BOOT;
+	else
+		early_console->flags |= CON_BOOT;
+	register_console(early_console);
+}
 
 static int __init setup_early_printk(char *buf)
 {
-	int keep_early;
+	int keep;
 
 	if (!buf)
 		return 0;
@@ -188,42 +197,34 @@ static int __init setup_early_printk(char *buf)
 		return 0;
 	early_console_initialized = 1;
 
-	keep_early = (strstr(buf, "keep") != NULL);
+	keep = (strstr(buf, "keep") != NULL);
 
+	while (*buf != '\0') {
 		if (!strncmp(buf, "serial", 6)) {
 			early_serial_init(buf + 6);
-		early_console = &early_serial_console;
-	} else if (!strncmp(buf, "ttyS", 4)) {
-		early_serial_init(buf);
-		early_console = &early_serial_console;
-	} else if (!strncmp(buf, "vga", 3)
-		&& boot_params.screen_info.orig_video_isVGA == 1) {
+			early_console_register(&early_serial_console, keep);
+		}
+		if (!strncmp(buf, "ttyS", 4)) {
+			early_serial_init(buf + 4);
+			early_console_register(&early_serial_console, keep);
+		}
+		if (!strncmp(buf, "vga", 3) &&
+		    boot_params.screen_info.orig_video_isVGA == 1) {
 			max_xpos = boot_params.screen_info.orig_video_cols;
 			max_ypos = boot_params.screen_info.orig_video_lines;
 			current_ypos = boot_params.screen_info.orig_y;
-		early_console = &early_vga_console;
+			early_console_register(&early_vga_console, keep);
+		}
 #ifdef CONFIG_EARLY_PRINTK_DBGP
-	} else if (!strncmp(buf, "dbgp", 4)) {
-		if (early_dbgp_init(buf+4) < 0)
-			return 0;
-		early_console = &early_dbgp_console;
-		/*
-		 * usb subsys will reset ehci controller, so don't keep
-		 * that early console
-		 */
-		keep_early = 0;
+		if (!strncmp(buf, "dbgp", 4) && !early_dbgp_init(buf + 4))
+			early_console_register(&early_dbgp_console, keep);
 #endif
 #ifdef CONFIG_HVC_XEN
-	} else if (!strncmp(buf, "xen", 3)) {
-		early_console = &xenboot_console;
+		if (!strncmp(buf, "xen", 3))
+			early_console_register(&xenboot_console, keep);
 #endif
+		buf++;
 	}
-
-	if (keep_early)
-		early_console->flags &= ~CON_BOOT;
-	else
-		early_console->flags |= CON_BOOT;
-	register_console(early_console);
 	return 0;
 }