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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Hulk Robot <hulkci@huawei.com>,
        YueHaibing <yuehaibing@huawei.com>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 4.14 012/107] net-sysfs: call dev_hold if kobject_init_and_add success
Date:   Mon,  1 Apr 2019 19:01:27 +0200
Message-Id: <20190401170046.650636106@linuxfoundation.org>
In-Reply-To: <20190401170045.246405031@linuxfoundation.org>
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4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: YueHaibing <yuehaibing@huawei.com>

[ Upstream commit a3e23f719f5c4a38ffb3d30c8d7632a4ed8ccd9e ]

In netdev_queue_add_kobject and rx_queue_add_kobject,
if sysfs_create_group failed, kobject_put will call
netdev_queue_release to decrease dev refcont, however
dev_hold has not be called. So we will see this while
unregistering dev:

unregister_netdevice: waiting for bcsh0 to become free. Usage count = -1

Reported-by: Hulk Robot <hulkci@huawei.com>
Fixes: d0d668371679 ("net: don't decrement kobj reference count on init failure")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/core/net-sysfs.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -917,6 +917,8 @@ static int rx_queue_add_kobject(struct n
 	if (error)
 		return error;
 
+	dev_hold(queue->dev);
+
 	if (dev->sysfs_rx_queue_group) {
 		error = sysfs_create_group(kobj, dev->sysfs_rx_queue_group);
 		if (error) {
@@ -926,7 +928,6 @@ static int rx_queue_add_kobject(struct n
 	}
 
 	kobject_uevent(kobj, KOBJ_ADD);
-	dev_hold(queue->dev);
 
 	return error;
 }
@@ -1327,6 +1328,8 @@ static int netdev_queue_add_kobject(stru
 	if (error)
 		return error;
 
+	dev_hold(queue->dev);
+
 #ifdef CONFIG_BQL
 	error = sysfs_create_group(kobj, &dql_group);
 	if (error) {
@@ -1336,7 +1339,6 @@ static int netdev_queue_add_kobject(stru
 #endif
 
 	kobject_uevent(kobj, KOBJ_ADD);
-	dev_hold(queue->dev);
 
 	return 0;
 }