Merge branch 'console-registration-cleanup' into for-linus

Author: pmladek

kernel/printk/printk.c

@@ -280,7 +280,6 @@ static struct console *exclusive_console;
 static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES];
 
 static int preferred_console = -1;
-static bool has_preferred_console;
 int console_set_on_cmdline;
 EXPORT_SYMBOL(console_set_on_cmdline);
 
@@ -2861,7 +2860,8 @@ early_param("keep_bootcon", keep_bootcon_setup);
  * Care need to be taken with consoles that are statically
  * enabled such as netconsole
  */
-static int try_enable_new_console(struct console *newcon, bool user_specified)
+static int try_enable_preferred_console(struct console *newcon,
+					bool user_specified)
 {
 	struct console_cmdline *c;
 	int i, err;
@@ -2891,10 +2891,8 @@ static int try_enable_new_console(struct console *newcon, bool user_specified)
 				return err;
 		}
 		newcon->flags |= CON_ENABLED;
-		if (i == preferred_console) {
+		if (i == preferred_console)
 			newcon->flags |= CON_CONSDEV;
-			has_preferred_console = true;
-		}
 		return 0;
 	}
 
@@ -2909,6 +2907,21 @@ static int try_enable_new_console(struct console *newcon, bool user_specified)
 	return -ENOENT;
 }
 
+/* Try to enable the console unconditionally */
+static void try_enable_default_console(struct console *newcon)
+{
+	if (newcon->index < 0)
+		newcon->index = 0;
+
+	if (newcon->setup && newcon->setup(newcon, NULL) != 0)
+		return;
+
+	newcon->flags |= CON_ENABLED;
+
+	if (newcon->device)
+		newcon->flags |= CON_CONSDEV;
+}
+
 /*
  * The console driver calls this routine during kernel initialization
  * to register the console printing procedure with printk() and to
@@ -2930,59 +2943,56 @@ static int try_enable_new_console(struct console *newcon, bool user_specified)
  */
 void register_console(struct console *newcon)
 {
-	struct console *bcon = NULL;
+	struct console *con;
+	bool bootcon_enabled = false;
+	bool realcon_enabled = false;
 	int err;
 
-	for_each_console(bcon) {
-		if (WARN(bcon == newcon, "console '%s%d' already registered\n",
-					 bcon->name, bcon->index))
+	for_each_console(con) {
+		if (WARN(con == newcon, "console '%s%d' already registered\n",
+					 con->name, con->index))
 			return;
 	}
 
-	/*
-	 * before we register a new CON_BOOT console, make sure we don't
-	 * already have a valid console
-	 */
-	if (newcon->flags & CON_BOOT) {
-		for_each_console(bcon) {
-			if (!(bcon->flags & CON_BOOT)) {
-				pr_info("Too late to register bootconsole %s%d\n",
-					newcon->name, newcon->index);
-				return;
-			}
-		}
+	for_each_console(con) {
+		if (con->flags & CON_BOOT)
+			bootcon_enabled = true;
+		else
+			realcon_enabled = true;
 	}
 
-	if (console_drivers && console_drivers->flags & CON_BOOT)
-		bcon = console_drivers;
-
-	if (!has_preferred_console || bcon || !console_drivers)
-		has_preferred_console = preferred_console >= 0;
+	/* Do not register boot consoles when there already is a real one. */
+	if (newcon->flags & CON_BOOT && realcon_enabled) {
+		pr_info("Too late to register bootconsole %s%d\n",
+			newcon->name, newcon->index);
+		return;
+	}
 
 	/*
-	 *	See if we want to use this console driver. If we
-	 *	didn't select a console we take the first one
-	 *	that registers here.
+	 * See if we want to enable this console driver by default.
+	 *
+	 * Nope when a console is preferred by the command line, device
+	 * tree, or SPCR.
+	 *
+	 * The first real console with tty binding (driver) wins. More
+	 * consoles might get enabled before the right one is found.
+	 *
+	 * Note that a console with tty binding will have CON_CONSDEV
+	 * flag set and will be first in the list.
 	 */
-	if (!has_preferred_console) {
-		if (newcon->index < 0)
-			newcon->index = 0;
-		if (newcon->setup == NULL ||
-		    newcon->setup(newcon, NULL) == 0) {
-			newcon->flags |= CON_ENABLED;
-			if (newcon->device) {
-				newcon->flags |= CON_CONSDEV;
-				has_preferred_console = true;
-			}
+	if (preferred_console < 0) {
+		if (!console_drivers || !console_drivers->device ||
+		    console_drivers->flags & CON_BOOT) {
+			try_enable_default_console(newcon);
 		}
 	}
 
 	/* See if this console matches one we selected on the command line */
-	err = try_enable_new_console(newcon, true);
+	err = try_enable_preferred_console(newcon, true);
 
 	/* If not, try to match against the platform default(s) */
 	if (err == -ENOENT)
-		err = try_enable_new_console(newcon, false);
+		err = try_enable_preferred_console(newcon, false);
 
 	/* printk() messages are not printed to the Braille console. */
 	if (err || newcon->flags & CON_BRL)
@@ -2994,8 +3004,10 @@ void register_console(struct console *newcon)
 	 * the real console are the same physical device, it's annoying to
 	 * see the beginning boot messages twice
 	 */
-	if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV))
+	if (bootcon_enabled &&
+	    ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) {
 		newcon->flags &= ~CON_PRINTBUFFER;
+	}
 
 	/*
 	 *	Put this console in the list - keep the
@@ -3051,15 +3063,15 @@ void register_console(struct console *newcon)
 	pr_info("%sconsole [%s%d] enabled\n",
 		(newcon->flags & CON_BOOT) ? "boot" : "" ,
 		newcon->name, newcon->index);
-	if (bcon &&
+	if (bootcon_enabled &&
 	    ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV) &&
 	    !keep_bootcon) {
 		/* We need to iterate through all boot consoles, to make
 		 * sure we print everything out, before we unregister them.
 		 */
-		for_each_console(bcon)
-			if (bcon->flags & CON_BOOT)
-				unregister_console(bcon);
+		for_each_console(con)
+			if (con->flags & CON_BOOT)
+				unregister_console(con);
 	}
 }
 EXPORT_SYMBOL(register_console);