Re: [PATCH] virtio-9p-device: fix memleak in virtio_9p_device_unrealize

[Pan Nengyuan <pannengyuan@huawei.com>]

On 1/14/2020 10:17 PM, Christian Schoenebeck wrote:
> On Dienstag, 14. Januar 2020 11:08:59 CET Christian Schoenebeck wrote:
>> On Dienstag, 14. Januar 2020 08:40:20 CET pannengyuan@huawei.com wrote:
>>> From: Pan Nengyuan <pannengyuan@huawei.com>
>>>
>>> v->vq forgot to cleanup in virtio_9p_device_unrealize, the memory leak
>>> stack is as follow:
>>>
>>> Direct leak of 14336 byte(s) in 2 object(s) allocated from:
>>>   #0 0x7f819ae43970 (/lib64/libasan.so.5+0xef970)  ??:?
>>>   #1 0x7f819872f49d (/lib64/libglib-2.0.so.0+0x5249d)  ??:?
>>>   #2 0x55a3a58da624 (./x86_64-softmmu/qemu-system-x86_64+0x2c14624)
>>>
>>> /mnt/sdb/qemu/hw/virtio/virtio.c:2327 #3 0x55a3a571bac7
>>> (./x86_64-softmmu/qemu-system-x86_64+0x2a55ac7)
>>> /mnt/sdb/qemu/hw/9pfs/virtio-9p-device.c:209 #4 0x55a3a58e7bc6
>>> (./x86_64-softmmu/qemu-system-x86_64+0x2c21bc6)
>>> /mnt/sdb/qemu/hw/virtio/virtio.c:3504 #5 0x55a3a5ebfb37
>>> (./x86_64-softmmu/qemu-system-x86_64+0x31f9b37)
>>> /mnt/sdb/qemu/hw/core/qdev.c:876
>>>
>>> Reported-by: Euler Robot <euler.robot@huawei.com>
>>> Signed-off-by: Pan Nengyuan <pannengyuan@huawei.com>
>>> ---
>>>
>>>  hw/9pfs/virtio-9p-device.c | 1 +
>>>  1 file changed, 1 insertion(+)
>>>
>>> diff --git a/hw/9pfs/virtio-9p-device.c b/hw/9pfs/virtio-9p-device.c
>>> index b5a7c03f26..b146387ae2 100644
>>> --- a/hw/9pfs/virtio-9p-device.c
>>> +++ b/hw/9pfs/virtio-9p-device.c
>>> @@ -215,6 +215,7 @@ static void virtio_9p_device_unrealize(DeviceState
>>> *dev, Error **errp) V9fsVirtioState *v = VIRTIO_9P(dev);
>>>
>>>      V9fsState *s = &v->state;
>>>
>>> +    virtio_delete_queue(v->vq);
>>>
>>>      virtio_cleanup(vdev);
>>>      v9fs_device_unrealize_common(s, errp);
>>>  
>>>  }
>>
>> Looks like you are using an old interface. The new one is
>>
>> 	void virtio_del_queue(VirtIODevice *vdev, int n);
> 
> Ah, my bad, it is actually the other way around, that is I was not up to date; 
> virtio_delete_queue() was apparently introduced a week ago:
> https://lists.gnu.org/archive/html/qemu-devel/2020-01/msg00723.html
> 
> The old virtio_del_queue() still exists though:
> https://github.com/qemu/qemu/blob/master/hw/virtio/virtio.c#L2339
> 
> Having said that, it would probably still make sense to use virtio_del_queue() 
> instead for now to make it easier for stable branches to merge this fix?
> 

virtio_delete_queue makes the cleanup more clear and it tends to replace the old one gradually.
So I think it would probably still use virtio_delete_queue.

Given that, maybe we can split this patch?
For example:
1. use virtio_del_queue to fix memleak, it's easier for stable to merge.
2. rename virtio_del_queue to virtio_delete_queue

> Best regards,
> Christian Schoenebeck
> 
> 
> 
> 
> .
>