[PATCH printk v2 38/38] printk, xen: fbfront: create/use safe function for forcing preferred

@@ -512,12 +512,8 @@ static void xenfb_make_preferred_console(void)
 	}
 	console_srcu_read_unlock(cookie);
 
-	if (c) {
-		unregister_console(c);
-		c->flags |= CON_CONSDEV;
-		c->flags &= ~CON_PRINTBUFFER; /* don't print again */
-		register_console(c);
-	}
+	if (c)
+		console_force_preferred(c);
 }
 
 static int xenfb_resume(struct xenbus_device *dev)

@@ -235,6 +235,7 @@ enum con_flush_mode {
 };
 
 extern int add_preferred_console(char *name, int idx, char *options);
+extern void console_force_preferred(struct console *c);
 extern void register_console(struct console *);
 extern int unregister_console(struct console *);
 extern void console_lock(void);

@@ -3207,38 +3207,17 @@ static void try_enable_default_console(struct console *newcon)
 
 static int unregister_console_locked(struct console *console);
 
-/*
- * The console driver calls this routine during kernel initialization
- * to register the console printing procedure with printk() and to
- * print any messages that were printed by the kernel before the
- * console driver was initialized.
- *
- * This can happen pretty early during the boot process (because of
- * early_printk) - sometimes before setup_arch() completes - be careful
- * of what kernel features are used - they may not be initialised yet.
- *
- * There are two types of consoles - bootconsoles (early_printk) and
- * "real" consoles (everything which is not a bootconsole) which are
- * handled differently.
- *  - Any number of bootconsoles can be registered at any time.
- *  - As soon as a "real" console is registered, all bootconsoles
- *    will be unregistered automatically.
- *  - Once a "real" console is registered, any attempt to register a
- *    bootconsoles will be rejected
- */
-void register_console(struct console *newcon)
+static void register_console_locked(struct console *newcon)
 {
 	struct console *con;
 	bool bootcon_enabled = false;
 	bool realcon_enabled = false;
 	int err;
 
-	console_list_lock();
-
 	for_each_console(con) {
 		if (WARN(con == newcon, "console '%s%d' already registered\n",
 					 con->name, con->index)) {
-			goto unlock;
+			return;
 		}
 
 		if (con->flags & CON_BOOT)

@@ -3251,7 +3230,7 @@ void register_console(struct console *newcon)
 	if (newcon->flags & CON_BOOT && realcon_enabled) {
 		pr_info("Too late to register bootconsole %s%d\n",
 			newcon->name, newcon->index);
-		goto unlock;
+		return;
 	}
 
 	/*

@@ -3282,7 +3261,7 @@ void register_console(struct console *newcon)
 
 	/* printk() messages are not printed to the Braille console. */
 	if (err || newcon->flags & CON_BRL)
-		goto unlock;
+		return;
 
 	/*
 	 * If we have a bootconsole, and are switching to a real console,

@@ -3346,7 +3325,31 @@ void register_console(struct console *newcon)
 				unregister_console_locked(con);
 		}
 	}
-unlock:
+}
+
+/*
+ * The console driver calls this routine during kernel initialization
+ * to register the console printing procedure with printk() and to
+ * print any messages that were printed by the kernel before the
+ * console driver was initialized.
+ *
+ * This can happen pretty early during the boot process (because of
+ * early_printk) - sometimes before setup_arch() completes - be careful
+ * of what kernel features are used - they may not be initialised yet.
+ *
+ * There are two types of consoles - bootconsoles (early_printk) and
+ * "real" consoles (everything which is not a bootconsole) which are
+ * handled differently.
+ *  - Any number of bootconsoles can be registered at any time.
+ *  - As soon as a "real" console is registered, all bootconsoles
+ *    will be unregistered automatically.
+ *  - Once a "real" console is registered, any attempt to register a
+ *    bootconsoles will be rejected
+ */
+void register_console(struct console *newcon)
+{
+	console_list_lock();
+	register_console_locked(newcon);
 	console_list_unlock();
 }
 EXPORT_SYMBOL(register_console);

@@ -3411,6 +3414,20 @@ int unregister_console(struct console *console)
 }
 EXPORT_SYMBOL(unregister_console);
 
+void console_force_preferred(struct console *c)
+{
+	console_list_lock();
+
+	if (unregister_console_locked(c) == 0) {
+		c->flags |= CON_CONSDEV;
+		c->flags &= ~CON_PRINTBUFFER; /* don't print again */
+		register_console_locked(c);
+	}
+
+	console_list_unlock();
+}
+EXPORT_SYMBOL(console_force_preferred);
+
 /*
  * Initialize the console device. This is called *early*, so
  * we can't necessarily depend on lots of kernel help here.