From: Wentao Wang <witallwang@gmail.com>
Date: Wed, 20 Mar 2019 15:30:39 +0000 (+0000)
Subject: Disable kgdboc failed by echo space to /sys/module/kgdboc/parameters/kgdboc
X-Git-Tag: v5.4-rc1~1304^2~1
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=3ec8002951ea173e24b466df1ea98c56b7920e63;p=platform%2Fkernel%2Flinux-rpi.git

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

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>
---

diff --git a/drivers/tty/serial/kgdboc.c b/drivers/tty/serial/kgdboc.c
index 6fb312e..bfe5e9e 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;