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Date: Thu, 26 Feb 2015 16:28:41 +0100
From: =?iso-8859-1?Q?Beno=EEt?= Canet <benoit.canet@irqsave.net>
To: huawei.xie@intel.com
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Subject: [dpdk-dev] vhost-user deconnection bug
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Hi Xie,

I connected a QEMU from git master with the vhost-user from git master
and noticed the following bug.

In the following code:

void                                                                            
user_destroy_device(struct vhost_device_ctx ctx)                                
{                                                                               
        struct virtio_net *dev = get_device(ctx);                               
                                                                                
        if (dev && (dev->flags & VIRTIO_DEV_RUNNING))                         
                notify_ops->destroy_device(dev);                                
                                                                                
        if (dev && dev->mem) {                                                  
                free_mem_region(dev);                                           
                free(dev->mem);                                                 
                dev->mem = NULL;                                                
        }                                                                       
}

The if (dev && (dev->flags & VIRTIO_DEV_RUNNING)) is evaluated false
and notify_ops->destroy_device(dev); is not called when QEMU terminate
and provocate the deconnexion.

As a consequence any piece of code busy polling or bursting on
the vhost-user device will segfault since it will not be notified
of the deconnexion.

By the way VIRTIO_DEV_RUNNING does not seem to be set anywhere.

Best regards

Benoît