linux-kernel - [PATCH v2 4/4] printk: Make console_{suspend,resume} handle CON

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Message-Id: <20251121-printk-cleanup-part2-v2-4-57b8b78647f4@suse.com>
Date: Fri, 21 Nov 2025 15:50:36 -0300
From: Marcos Paulo de Souza <mpdesouza@...e.com>
To: Petr Mladek <pmladek@...e.com>, Steven Rostedt <rostedt@...dmis.org>, 
 John Ogness <john.ogness@...utronix.de>, 
 Sergey Senozhatsky <senozhatsky@...omium.org>, 
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
 Jiri Slaby <jirislaby@...nel.org>, 
 Jason Wessel <jason.wessel@...driver.com>, 
 Daniel Thompson <danielt@...nel.org>, 
 Douglas Anderson <dianders@...omium.org>, 
 Richard Weinberger <richard@....at>, 
 Anton Ivanov <anton.ivanov@...bridgegreys.com>, 
 Johannes Berg <johannes@...solutions.net>
Cc: linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org, 
 kgdb-bugreport@...ts.sourceforge.net, linux-um@...ts.infradead.org, 
 Marcos Paulo de Souza <mpdesouza@...e.com>
Subject: [PATCH v2 4/4] printk: Make console_{suspend,resume} handle
 CON_SUSPENDED

Since commit 9e70a5e109a4 ("printk: Add per-console suspended state")
the CON_SUSPENDED flag was introced, and this flag was being checked
on console_is_usable function, which returns false if the console is
suspended.

To make the behavior consistent, change show_cons_active to look for
consoles that are not suspended, instead of checking CON_ENABLED.

Signed-off-by: Marcos Paulo de Souza <mpdesouza@...e.com>
---
 drivers/tty/tty_io.c   | 2 +-
 kernel/printk/printk.c | 5 +++--
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index e2d92cf70eb7..1b2ce0f36010 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -3554,7 +3554,7 @@ static ssize_t show_cons_active(struct device *dev,
 			continue;
 		if (!(c->flags & CON_NBCON) && !c->write)
 			continue;
-		if ((c->flags & CON_ENABLED) == 0)
+		if (c->flags & CON_SUSPENDED)
 			continue;
 		cs[i++] = c;
 		if (i >= ARRAY_SIZE(cs))
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index fed98a18e830..fe7c956f73bd 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -3542,7 +3542,7 @@ void console_suspend(struct console *console)
 {
 	__pr_flush(console, 1000, true);
 	console_list_lock();
-	console_srcu_write_flags(console, console->flags & ~CON_ENABLED);
+	console_srcu_write_flags(console, console->flags | CON_SUSPENDED);
 	console_list_unlock();
 
 	/*
@@ -3555,13 +3555,14 @@ void console_suspend(struct console *console)
 }
 EXPORT_SYMBOL(console_suspend);
 
+/* Unset CON_SUSPENDED flag so the console can start printing again. */
 void console_resume(struct console *console)
 {
 	struct console_flush_type ft;
 	bool is_nbcon;
 
 	console_list_lock();
-	console_srcu_write_flags(console, console->flags | CON_ENABLED);
+	console_srcu_write_flags(console, console->flags & ~CON_SUSPENDED);
 	is_nbcon = console->flags & CON_NBCON;
 	console_list_unlock();
 

-- 
2.51.1