linux-kernel - [PATCH 5/5] printk: Check CON_SUSPEND when unblanking a console

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Message-Id: <20250226-printk-renaming-v1-5-0b878577f2e6@suse.com>
Date: Wed, 26 Feb 2025 16:59:05 -0300
From: Marcos Paulo de Souza <mpdesouza@...e.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
 Eric Biederman <ebiederm@...ssion.com>, 
 "Rafael J. Wysocki" <rafael@...nel.org>, Len Brown <len.brown@...el.com>, 
 Pavel Machek <pavel@....cz>, Petr Mladek <pmladek@...e.com>, 
 Steven Rostedt <rostedt@...dmis.org>, 
 John Ogness <john.ogness@...utronix.de>, 
 Sergey Senozhatsky <senozhatsky@...omium.org>, 
 Todd E Brandt <todd.e.brandt@...ux.intel.com>, 
 Jiri Slaby <jirislaby@...nel.org>
Cc: linux-kernel@...r.kernel.org, kexec@...ts.infradead.org, 
 linux-pm@...r.kernel.org, linux-serial@...r.kernel.org, 
 Marcos Paulo de Souza <mpdesouza@...e.com>
Subject: [PATCH 5/5] printk: Check CON_SUSPEND when unblanking a console

The commit 9e70a5e109a4 ("printk: Add per-console suspended state")
introduced the CON_SUSPENDED flag for consoles. The suspended consoles
will stop receiving messages, so don't unblank suspended consoles
because it won't be showing anything either way.

Signed-off-by: Marcos Paulo de Souza <mpdesouza@...e.com>
---
 kernel/printk/printk.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index fbbaec06c9f3..4b7ed40bf808 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -3342,7 +3342,12 @@ void console_unblank(void)
 	 */
 	cookie = console_srcu_read_lock();
 	for_each_console_srcu(c) {
-		if ((console_srcu_read_flags(c) & CON_ENABLED) && c->unblank) {
+		short flags = console_srcu_read_flags(c);
+
+		if (flags & CON_SUSPENDED)
+			continue;
+
+		if ((flags & CON_ENABLED) && c->unblank) {
 			found_unblank = true;
 			break;
 		}
@@ -3379,7 +3384,12 @@ void console_unblank(void)

 	cookie = console_srcu_read_lock();
 	for_each_console_srcu(c) {
-		if ((console_srcu_read_flags(c) & CON_ENABLED) && c->unblank)
+		short flags = console_srcu_read_flags(c);
+
+		if (flags & CON_SUSPENDED)
+			continue;
+
+		if ((flags & CON_ENABLED) && c->unblank)
 			c->unblank();
 	}
 	console_srcu_read_unlock(cookie);

-- 
2.48.1