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    tuntap: forbid changing mq flag for persistent device · 8e6d91ae
    Jason Wang 提交于
    We currently allow changing the mq flag (IFF_MULTI_QUEUE) for a persistent
    device. This will result a mismatch between the number the queues in netdev and
    tuntap. This is because we only allocate a 1q netdevice when IFF_MULTI_QUEUE was
    not specified, so when we set the IFF_MULTI_QUEUE and try to attach more queues
    later, netif_set_real_num_tx_queues() may fail which result a single queue
    netdevice with multiple sockets attached.
    
    Solve this by disallowing changing the mq flag for persistent device.
    
    Bug was introduced by commit edfb6a14
    (tuntap: reduce memory using of queues).
    Reported-by: NSriram Narasimhan <sriram.narasimhan@hp.com>
    Cc: Michael S. Tsirkin <mst@redhat.com>
    Signed-off-by: NJason Wang <jasowang@redhat.com>
    Signed-off-by: NDavid S. Miller <davem@davemloft.net>
    8e6d91ae
tun.c 54.1 KB