[PATCH printk v5 37/40] tty: serial: kgdboc: synchronize tty_find_polling_driver() and register_console()
From: John Ogness <john.ogness@linutronix.de>
Date: 2022-11-16 16:26:07
Also in:
lkml
Subsystem:
kgdb / kdb /debug_core, the rest, tty layer and serial drivers · Maintainers:
Jason Wessel, Daniel Thompson, Linus Torvalds, Greg Kroah-Hartman, Jiri Slaby
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@linutronix.de> Reviewed-by: Daniel Thompson <redacted> Reviewed-by: Petr Mladek <pmladek@suse.com> --- 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
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2.30.2