Commit 0fb413ea authored by John Ogness's avatar John Ogness Committed by Petr Mladek
Browse files

tty: serial: kgdboc: document console_lock usage 



kgdboc_earlycon_init() uses the console_lock to ensure that no consoles
are unregistered until the kgdboc_earlycon is setup. This is necessary
because the trapping of the exit() callback assumes that the exit()
callback is not called before the trap is setup.

Explicitly document this non-typical console_lock usage.

Signed-off-by: default avatarJohn Ogness <john.ogness@linutronix.de>
Reviewed-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: default avatarDouglas Anderson <dianders@chromium.org>
Reviewed-by: default avatarDaniel Thompson <daniel.thompson@linaro.org>
Reviewed-by: default avatarPetr Mladek <pmladek@suse.com>
Signed-off-by: default avatarPetr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20221116162152.193147-9-john.ogness@linutronix.de
parent 3860e7c5

drivers/tty/serial/kgdboc.c

+8 −0
Original line number Diff line number Diff line
@@ -530,6 +530,14 @@ static int __init kgdboc_earlycon_init(char *opt) 
	 * Look for a matching console, or if the name was left blank just

	 * pick the first one we find.

	 */



	/*

	 * Hold the console_lock to guarantee that no consoles are

	 * unregistered until the kgdboc_earlycon setup is complete.

	 * Trapping the exit() callback relies on exit() not being

	 * called until the trap is setup. This also allows safe

	 * traversal of the console list and race-free reading of @flags.

	 */

	console_lock();

	for_each_console(con) {

		if (con->write && con->read &&