[PATCH v6 11/16] console/braille: Lock console->setup() call during the registration

[Petr Mladek <pmladek@suse.com>]

In braille_register_console(), the console->setup() callback must be
called while holding the console_lock. This prevents a race condition
with a possible active boot console that might be using the same hardware
registers.

See also the commit 801410b26a0e ("serial: Lock console when calling into
driver before registration").

Reported-by: Sashiko <sashiko-bot@kernel.org>
Closes: https://sashiko.dev/#/patchset/20260423130015.85175-1-pmladek%40suse.com
Suggested-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Acked-by: Chris Down <chris@chrisdown.name>
---
 drivers/accessibility/braille/braille_console.c | 10 +++++-----
 include/linux/console.h                         |  1 +
 kernel/printk/printk.c                          |  8 +++++++-
 3 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/drivers/accessibility/braille/braille_console.c b/drivers/accessibility/braille/braille_console.c
index 1b79b4d88bac..bc338e57d8ef 100644
--- a/drivers/accessibility/braille/braille_console.c
+++ b/drivers/accessibility/braille/braille_console.c
@@ -408,11 +408,11 @@ int braille_register_console(struct console *console, int index,
 		console_options = "57600o8";
 	if (braille_co)
 		return -ENODEV;
-	if (console->setup) {
-		ret = console->setup(console, console_options);
-		if (ret != 0)
-			return ret;
-	}
+
+	ret = console_call_setup(console, console_options);
+	if (ret != 0)
+		return ret;
+
 	console->flags |= CON_ENABLED | CON_BRL;
 	console->index = index;
 	braille_co = console;
diff --git a/include/linux/console.h b/include/linux/console.h
index cb8be9ea4a76..b68279a22514 100644
--- a/include/linux/console.h
+++ b/include/linux/console.h
@@ -710,6 +710,7 @@ enum con_flush_mode {
 };
 
 extern int add_preferred_console(const char *name, const short idx, char *options);
+extern int console_call_setup(struct console *newcon, char *options);
 extern void console_force_preferred_locked(struct console *con);
 extern void register_console(struct console *);
 extern int unregister_console(struct console *);
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 49c5624eede0..0e68af9a3490 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -3957,7 +3957,13 @@ static int __init keep_bootcon_setup(char *str)
 
 early_param("keep_bootcon", keep_bootcon_setup);
 
-static int console_call_setup(struct console *newcon, char *options)
+/*
+ * The function is intended only for the generic console registration code.
+ * It has been made global only for the Braille console driver which
+ * is partly using the generic console registration code but it is
+ * integrated with VT code instead of printk().
+ */
+int console_call_setup(struct console *newcon, char *options)
 {
 	int err;
 
-- 
2.56.0