netdev - [PATCH] isdn/i4l: add error handling for try_module

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Date:   Tue, 12 Jun 2018 12:43:53 +0800
From:   Zhouyang Jia <jiazhouyang09@...il.com>
To:     unlisted-recipients:; (no To-header on input)
Cc:     Zhouyang Jia <jiazhouyang09@...il.com>,
        Karsten Keil <isdn@...ux-pingi.de>,
        Kees Cook <keescook@...omium.org>,
        Annie Cherkaev <annie.cherk@...il.com>,
        Al Viro <viro@...iv.linux.org.uk>,
        Jiten Thakkar <jitenmt@...il.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] isdn/i4l: add error handling for try_module_get

When try_module_get fails, the lack of error-handling code may
cause unexpected results.

This patch adds error-handling code after calling try_module_get.

Signed-off-by: Zhouyang Jia <jiazhouyang09@...il.com>
---
 drivers/isdn/i4l/isdn_common.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/isdn/i4l/isdn_common.c b/drivers/isdn/i4l/isdn_common.c
index 7c6f3f5..7e52851 100644
--- a/drivers/isdn/i4l/isdn_common.c
+++ b/drivers/isdn/i4l/isdn_common.c
@@ -71,7 +71,8 @@ static int isdn_add_channels(isdn_driver_t *d, int drvidx, int n, int adding);
 static inline void
 isdn_lock_driver(isdn_driver_t *drv)
 {
-	try_module_get(drv->interface->owner);
+	if (!try_module_get(drv->interface->owner))
+		printk(KERN_WARNING "isdn_lock_driver: cannot get module\n");
 	drv->locks++;
 }
 
-- 
2.7.4