2013-06-13 13:10:10

by Benjamin Poirier

Subject: [PATCH] netiucv: Hold rtnl between name allocation and device registration.

fixes a race condition between concurrent initializations of netiucv devices
that try to use the same name.

sysfs: cannot create duplicate filename '/devices/iucv/netiucv2'
[...]
Call Trace:
([<00000000002edea4>] sysfs_add_one+0xb0/0xdc)
[<00000000002eecd4>] create_dir+0x80/0xfc
[<00000000002eee38>] sysfs_create_dir+0xe8/0x118
[<00000000003835a8>] kobject_add_internal+0x120/0x2d0
[<00000000003839d6>] kobject_add+0x62/0x9c
[<00000000003d9564>] device_add+0xcc/0x510
[<000003e00212c7b4>] netiucv_register_device+0xc0/0x1ec [netiucv]

Signed-off-by: Benjamin Poirier <[email protected]>
Tested-by: Ursula Braun <[email protected]>
---
drivers/s390/net/netiucv.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/s390/net/netiucv.c b/drivers/s390/net/netiucv.c
index 4ffa66c..9ca3996 100644
--- a/drivers/s390/net/netiucv.c
+++ b/drivers/s390/net/netiucv.c
@@ -2040,6 +2040,7 @@ static struct net_device *netiucv_init_netdevice(char *username, char *userdata)
netiucv_setup_netdevice);
if (!dev)
return NULL;
+ rtnl_lock();
if (dev_alloc_name(dev, dev->name) < 0)
goto out_netdev;

@@ -2061,6 +2062,7 @@ static struct net_device *netiucv_init_netdevice(char *username, char *userdata)
out_fsm:
kfree_fsm(privptr->fsm);
out_netdev:
+ rtnl_unlock();
free_netdev(dev);
return NULL;
}
@@ -2100,6 +2102,7 @@ static ssize_t conn_write(struct device_driver *drv,

rc = netiucv_register_device(dev);
if (rc) {
+ rtnl_unlock();
IUCV_DBF_TEXT_(setup, 2,
"ret %d from netiucv_register_device\n", rc);
goto out_free_ndev;
@@ -2109,7 +2112,8 @@ static ssize_t conn_write(struct device_driver *drv,
priv = netdev_priv(dev);
SET_NETDEV_DEV(dev, priv->dev);

- rc = register_netdev(dev);
+ rc = register_netdevice(dev);
+ rtnl_unlock();
if (rc)
goto out_unreg;

--
1.7.10.4

2013-06-14 00:41:56

by David Miller

Subject: Re: [PATCH] netiucv: Hold rtnl between name allocation and device registration.

From: Benjamin Poirier <[email protected]>
Date: Thu, 13 Jun 2013 09:09:47 -0400

> fixes a race condition between concurrent initializations of netiucv devices
> that try to use the same name.
>
> sysfs: cannot create duplicate filename '/devices/iucv/netiucv2'
> [...]
> Call Trace:
> ([<00000000002edea4>] sysfs_add_one+0xb0/0xdc)
> [<00000000002eecd4>] create_dir+0x80/0xfc
> [<00000000002eee38>] sysfs_create_dir+0xe8/0x118
> [<00000000003835a8>] kobject_add_internal+0x120/0x2d0
> [<00000000003839d6>] kobject_add+0x62/0x9c
> [<00000000003d9564>] device_add+0xcc/0x510
> [<000003e00212c7b4>] netiucv_register_device+0xc0/0x1ec [netiucv]
>
> Signed-off-by: Benjamin Poirier <[email protected]>
> Tested-by: Ursula Braun <[email protected]>

Yes as dev_alloc_name() must be invoked under RTNL or dev_base_lock, this
fix is correct.

Applied, thanks.