Calling tty_find_polling_driver() can lead to uart_set_options() being
called (via the poll_init() callback of tty_operations) to configure the
uart. But uart_set_options() can also be called by register_console()
(via the setup() callback of console).
Take the console_list_lock to synchronize against register_console() and
also use it for console list traversal. This also ensures the console list
cannot change until the polling console has been chosen.
Signed-off-by: John Ogness <john.ogness@xxxxxxxxxxxxx>
---
drivers/tty/serial/kgdboc.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)
diff --git a/drivers/tty/serial/kgdboc.c b/drivers/tty/serial/kgdboc.c
index 82b4b4d67823..8c2b7ccdfebf 100644
--- a/drivers/tty/serial/kgdboc.c
+++ b/drivers/tty/serial/kgdboc.c
@@ -189,12 +189,20 @@ static int configure_kgdboc(void)
if (kgdboc_register_kbd(&cptr))
goto do_register;
+ /*
+ * tty_find_polling_driver() can call uart_set_options()
+ * (via poll_init) to configure the uart. Take the console_list_lock
+ * in order to synchronize against register_console(), which can also
+ * configure the uart via uart_set_options(). This also allows safe
+ * traversal of the console list.
+ */
+ console_list_lock();
+
p = tty_find_polling_driver(cptr, &tty_line);
- if (!p)
+ if (!p) {
+ console_list_unlock();
goto noconfig;
-
- /* For safe traversal of the console list. */
- console_list_lock();
+ }
/*
* Take console_lock to serialize device() callback with
--
2.30.2
