[tip: sched/rt] printk: Flush console on unregister_console()

[tip-bot2 for John Ogness]

The following commit has been merged into the sched/rt branch of tip:

Commit-ID:     0e53e2d9f72080b7ea1a4003558041fee78cdef9
Gitweb:        https://git.kernel.org/tip/0e53e2d9f72080b7ea1a4003558041fee78cdef9
Author:        John Ogness <john.ogness@xxxxxxxxxxxxx>
AuthorDate:    Wed, 04 Sep 2024 14:11:22 +02:06
Committer:     Petr Mladek <pmladek@xxxxxxxx>
CommitterDate: Wed, 04 Sep 2024 15:56:32 +02:00

printk: Flush console on unregister_console()

Ensure consoles have flushed pending records before
unregistering. The console should print up to at least its
related "console disabled" record.

Signed-off-by: John Ogness <john.ogness@xxxxxxxxxxxxx>
Reviewed-by: Petr Mladek <pmladek@xxxxxxxx>
Link: https://lore.kernel.org/r/20240904120536.115780-4-john.ogness@xxxxxxxxxxxxx
Signed-off-by: Petr Mladek <pmladek@xxxxxxxx>
---
 kernel/printk/printk.c |  9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index acf6680..c79e962 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -3771,11 +3771,16 @@ static int unregister_console_locked(struct console *console)
 	if (res > 0)
 		return 0;
 
+	if (!console_is_registered_locked(console))
+		res = -ENODEV;
+	else if (console_is_usable(console, console->flags))
+		__pr_flush(console, 1000, true);
+
 	/* Disable it unconditionally */
 	console_srcu_write_flags(console, console->flags & ~CON_ENABLED);
 
-	if (!console_is_registered_locked(console))
-		return -ENODEV;
+	if (res < 0)
+		return res;
 
 	/*
 	 * Use the driver synchronization to ensure that the hardware is not