Disable kgdboc failed by echo space to /sys/module/kgdboc/parameters/kgdboc

BugLink: https://bugs.launchpad.net/bugs/1838116
commit 3ec8002951ea173e24b466df1ea98c56b7920e63 upstream.

Echo "" to /sys/module/kgdboc/parameters/kgdboc will fail with "No such
device” error.

This is caused by function "configure_kgdboc" who init err to ENODEV
when the config is empty (legal input) the code go out with ENODEV
returned.

Fixes: 2dd453168643 ("kgdboc: Fix restrict error")
Signed-off-by: Wentao Wang <witallwang@gmail.com>
Cc: stable <stable@vger.kernel.org>
Acked-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/drivers/tty/serial/kgdboc.c b/drivers/tty/serial/kgdboc.c
index 93d3a0ec5e112138fe46f7f3fea5c0882da20468..b0aa864f84a97ed61b1ffecdd79551cfdb414dca 100644 (file)
--- a/drivers/tty/serial/kgdboc.c
+++ b/drivers/tty/serial/kgdboc.c
@@ -145,8 +145,10 @@ static int configure_kgdboc(void)
        char *cptr = config;
        struct console *cons;
 
-       if (!strlen(config) || isspace(config[0]))
+       if (!strlen(config) || isspace(config[0])) {
+               err = 0;
                goto noconfig;
+       }
 
        kgdboc_io_ops.is_console = 0;
        kgdb_tty_driver = NULL;