Re: [PATCH net-next] net: core: fix the order in dev_put() and rtnl_lock()

[Nikolay Aleksandrov]

On 14/09/2021 08:18, Eric Dumazet wrote:
> 
> 
> On 9/13/21 8:01 PM, Yajun Deng wrote:
>> The dev_put() should be after rtnl_lock() in case for race.
>>
>> Fixes: 893b19587534 ("net: bridge: fix ioctl locking")
>> Signed-off-by: Yajun Deng <yajun.deng@xxxxxxxxx>
>> ---
>>  net/core/dev_ioctl.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/net/core/dev_ioctl.c b/net/core/dev_ioctl.c
>> index 0e87237fd871..9796fa35fe88 100644
>> --- a/net/core/dev_ioctl.c
>> +++ b/net/core/dev_ioctl.c
>> @@ -384,8 +384,8 @@ static int dev_ifsioc(struct net *net, struct ifreq *ifr, void __user *data,
>>  		dev_hold(dev);
>>  		rtnl_unlock();
>>  		err = br_ioctl_call(net, netdev_priv(dev), cmd, ifr, NULL);
>> -		dev_put(dev);
>>  		rtnl_lock();
>> +		dev_put(dev);
>>  		return err;
>>  
>>  	case SIOCSHWTSTAMP:
>>
> 
> What race exactly are you trying to avoid ?
> 
> This patch does not look needed to me.
> 

+1 

There isn't a race there