linux-kernel - [PATCH] net-sysfs: call dev_hold if kobject_init_and

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Date:   Tue, 19 Mar 2019 10:16:53 +0800
From:   Yue Haibing <yuehaibing@...wei.com>
To:     <davem@...emloft.net>, <idosch@...lanox.com>,
        <alexander.h.duyck@...el.com>, <tyhicks@...onical.com>
CC:     <linux-kernel@...r.kernel.org>, <netdev@...r.kernel.org>,
        YueHaibing <yuehaibing@...wei.com>
Subject: [PATCH] net-sysfs: call dev_hold if kobject_init_and_add success

From: YueHaibing <yuehaibing@...wei.com>

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@...wei.com>
Fixes: d0d668371679 ("net: don't decrement kobj reference count on init failure")
Signed-off-by: YueHaibing <yuehaibing@...wei.com>
---
 net/core/net-sysfs.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 4ff661f..8f8b7b6 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -928,6 +928,8 @@ static int rx_queue_add_kobject(struct net_device *dev, int index)
 	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) {
@@ -937,7 +939,6 @@ static int rx_queue_add_kobject(struct net_device *dev, int index)
 	}
 
 	kobject_uevent(kobj, KOBJ_ADD);
-	dev_hold(queue->dev);
 
 	return error;
 }
@@ -1464,6 +1465,8 @@ static int netdev_queue_add_kobject(struct net_device *dev, int index)
 	if (error)
 		return error;
 
+	dev_hold(queue->dev);
+
 #ifdef CONFIG_BQL
 	error = sysfs_create_group(kobj, &dql_group);
 	if (error) {
@@ -1473,7 +1476,6 @@ static int netdev_queue_add_kobject(struct net_device *dev, int index)
 #endif
 
 	kobject_uevent(kobj, KOBJ_ADD);
-	dev_hold(queue->dev);
 
 	return 0;
 }
-- 
2.7.0