[PATCH 8/8] printk: Try enable preferred consoles only when there are any

[Petr Mladek <pmladek@suse.com>]

try_enable_preferred_console() used to be always called because it
had several hidden effects, namely:

- enabled Braille consoles which were ignored by "preferred_dev_console"
  because they were not associated with /dev/console.

- returned success when a console was pre-enabled using CON_ENABLED
  flag.

- returned success when a console was enabled by default because
  try_enable_default_console() did not return success.

The first two hidden effects were removed in previous patches. Remove
the last one so that try_enable_preferred_console() can be called only
when any non-Braille console is preferred.

Signed-off-by: Petr Mladek <pmladek@suse.com>
---
 kernel/printk/printk.c | 25 ++++++++++++++-----------
 1 file changed, 14 insertions(+), 11 deletions(-)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index db91be780de9..462d870feaf2 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -3975,18 +3975,23 @@ static int try_enable_braille_console(struct console *newcon)
 }
 
 /* Try to enable the console unconditionally */
-static void try_enable_default_console(struct console *newcon)
+static int try_enable_default_console(struct console *newcon)
 {
+	int err;
+
 	if (newcon->index < 0)
 		newcon->index = 0;
 
-	if (console_call_setup(newcon, NULL) != 0)
-		return;
+	err = console_call_setup(newcon, NULL);
+	if (err)
+		return err;
 
 	newcon->flags |= CON_ENABLED;
 
 	if (newcon->device)
 		newcon->flags |= CON_CONSDEV;
+
+	return 0;
 }
 
 /* Return the starting sequence number for a newly registered console. */
@@ -4156,17 +4161,15 @@ void register_console(struct console *newcon)
 	if (preferred_dev_console < 0) {
 		if (hlist_empty(&console_list) || !console_first()->device ||
 		    console_first()->flags & CON_BOOT) {
-			try_enable_default_console(newcon);
+			err = try_enable_default_console(newcon);
 		}
+	} else {
+		err = try_enable_preferred_console(newcon, true);
+
+		if (err == -ENOENT)
+			err = try_enable_preferred_console(newcon, false);
 	}
 
-	/* See if this console matches one we selected on the command line */
-	err = try_enable_preferred_console(newcon, true);
-
-	/* If not, try to match against the platform default(s) */
-	if (err == -ENOENT)
-		err = try_enable_preferred_console(newcon, false);
-
 	/*
 	 * Some consoles, such as pstore and netconsole, can be enabled even
 	 * without matching. Accept them at this stage when they had a chance
-- 
2.52.0