diff options
| author | John Ogness | 2022-11-16 17:27:20 +0106 |
|---|---|---|
| committer | Petr Mladek | 2022-12-02 11:25:00 +0100 |
| commit | 0fb413ea64603a71e19b4b15a6c5b704e3897d06 (patch) | |
| tree | ddf789a84cf447301b08bab6c1842e69c87d9666 /drivers/tty | |
| parent | 3860e7c57fd23e744e045436f9872fb9d01381e2 (diff) | |
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: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20221116162152.193147-9-john.ogness@linutronix.de
Diffstat (limited to 'drivers/tty')
| -rw-r--r-- | drivers/tty/serial/kgdboc.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/drivers/tty/serial/kgdboc.c b/drivers/tty/serial/kgdboc.c index e76f0186c335..5be381003e58 100644 --- a/drivers/tty/serial/kgdboc.c +++ b/drivers/tty/serial/kgdboc.c @@ -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 && |