| Message ID | 20221107141638.3790965-13-john.ogness@linutronix.de |
|---|---|
| State | Superseded |
| Headers | show |
| Series | reduce console_lock scope | expand |
On Mon, Nov 07, 2022 at 03:22:10PM +0106, John Ogness wrote: > 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> Daniel.
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 &&