Re: [PATCH v3 2/6] nbd: disallow NBD_SET_SOCK on an active device

[yangerkun <yangerkun@huawei.com>]

在 2026/7/22 11:03, yu kuai 写道:
> Hi,
> 
> 在 2026/7/13 14:56, Yang Erkun 写道:
>> We cannot add a socket to an already running nbd device, the reconfigure
>> for netlink can only active dead socket. But for ioctl path, we can call
>> NBD_SET_SOCK after NBD_DO_IT, reject this using nbd->pid which has been
>> setted when NBD_DO_IT. Besides, it is the root cause for commit
>> b98e762e3d71 ("nbd: freeze the queue while we're adding connections").
>>
>> Signed-off-by: Yang Erkun <yangerkun@huawei.com>
>> ---
>>    drivers/block/nbd.c | 7 +++++++
>>    1 file changed, 7 insertions(+)
>>
>> diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
>> index b1a5acd57426..a15553ab4b97 100644
>> --- a/drivers/block/nbd.c
>> +++ b/drivers/block/nbd.c
>> @@ -1302,6 +1302,13 @@ static int nbd_add_socket(struct nbd_device *nbd, unsigned long arg,
>>    		goto put_socket;
>>    	}
>>    
>> +	if (nbd->pid) {
>> +		dev_err(disk_to_dev(nbd->disk),
>> +			"Cannot add socket to a running device\n");
>> +		err = -EBUSY;
>> +		goto put_socket;
>> +	}
> 
> I think the checking if fine, but I'd like to add the checking before nbd_get_socket() and
> return -EBUSY directly.

OK.
> 
>> +
>>    	nsock = kzalloc_obj(*nsock);
>>    	if (!nsock) {
>>    		err = -ENOMEM;
>