patch "Disable kgdboc failed by echo space to" added to tty-linus

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    Disable kgdboc failed by echo space to

to my tty git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git
in the tty-linus branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.

If you have any questions about this process, please let me know.


From 3ec8002951ea173e24b466df1ea98c56b7920e63 Mon Sep 17 00:00:00 2001
From: Wentao Wang <witallwang@gmail.com>
Date: Wed, 20 Mar 2019 15:30:39 +0000
Subject: Disable kgdboc failed by echo space to
 /sys/module/kgdboc/parameters/kgdboc
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

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>
---
 drivers/tty/serial/kgdboc.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/kgdboc.c b/drivers/tty/serial/kgdboc.c
index 6fb312e7af71..bfe5e9e034ec 100644
--- a/drivers/tty/serial/kgdboc.c
+++ b/drivers/tty/serial/kgdboc.c
@@ -148,8 +148,10 @@ 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;
-- 
2.21.0