• Wei Liu's avatar
    xen-netback: bookkeep number of active queues in our own module · f7b50c4e
    Wei Liu authored
    The original code uses netdev->real_num_tx_queues to bookkeep number of
    queues and invokes netif_set_real_num_tx_queues to set the number of
    queues. However, netif_set_real_num_tx_queues doesn't allow
    real_num_tx_queues to be smaller than 1, which means setting the number
    to 0 will not work and real_num_tx_queues is untouched.
    
    This is bogus when xenvif_free is invoked before any number of queues is
    allocated. That function needs to iterate through all queues to free
    resources. Using the wrong number of queues results in NULL pointer
    dereference.
    
    So we bookkeep the number of queues in xen-netback to solve this
    problem. This fixes a regression introduced by multiqueue patchset in
    3.16-rc1.
    
    There's another bug in original code that the real number of RX queues
    is never set. In current Xen multiqueue design, the number of TX queues
    and RX queues are in fact the same. We need to set the numbers of TX and
    RX queues to the same value.
    
    Also remove xenvif_select_queue and leave queue selection to core
    driver, as suggested by David Miller.
    Reported-by: default avatarBoris Ostrovsky <boris.ostrovsky@oracle.com>
    Signed-off-by: default avatarWei Liu <wei.liu2@citrix.com>
    CC: Ian Campbell <ian.campbell@citrix.com>
    CC: Paul Durrant <paul.durrant@citrix.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    f7b50c4e
interface.c 19 KB