linux-kernel - [PATCH 3.16 029/157] net-sysfs: call dev_hold if kobject_init_and

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Message-ID: <lsq.1565469607.156035753@decadent.org.uk>
Date:   Sat, 10 Aug 2019 21:40:07 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Hulk Robot" <hulkci@...wei.com>,
        "YueHaibing" <yuehaibing@...wei.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 3.16 029/157] net-sysfs: call dev_hold if kobject_init_and_add
 success

3.16.72-rc1 review patch.  If anyone has any objections, please let me know.

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

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

commit a3e23f719f5c4a38ffb3d30c8d7632a4ed8ccd9e upstream.

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>
Signed-off-by: David S. Miller <davem@...emloft.net>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 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
@@ -788,6 +788,8 @@ static int rx_queue_add_kobject(struct n
 	if (error)
 		return error;
 
+	dev_hold(queue->dev);
+
 	if (net->sysfs_rx_queue_group) {
 		error = sysfs_create_group(kobj, net->sysfs_rx_queue_group);
 		if (error) {
@@ -797,7 +799,6 @@ static int rx_queue_add_kobject(struct n
 	}
 
 	kobject_uevent(kobj, KOBJ_ADD);
-	dev_hold(queue->dev);
 
 	return error;
 }
@@ -1146,6 +1147,8 @@ 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) {
@@ -1155,7 +1158,6 @@ static int netdev_queue_add_kobject(stru
 #endif
 
 	kobject_uevent(kobj, KOBJ_ADD);
-	dev_hold(queue->dev);
 
 	return 0;
 }