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    rtl8139: flush queued packets when RxBufPtr is written · 00b7ade8
    Stefan Hajnoczi 提交于
    Net queues support efficient "receive disable".  For example, tap's file
    descriptor will not be polled while its peer has receive disabled.  This
    saves CPU cycles for needlessly copying and then dropping packets which
    the peer cannot receive.
    
    rtl8139 is missing the qemu_flush_queued_packets() call that wakes the
    queue up when receive becomes possible again.
    
    As a result, the Windows 7 guest driver reaches a state where the
    rtl8139 cannot receive packets.  The driver has actually refilled the
    receive buffer but we never resume reception.
    
    The bug can be reproduced by running a large FTP 'get' inside a Windows
    7 guest:
    
      $ qemu -netdev tap,id=tap0,...
             -device rtl8139,netdev=tap0
    
    The Linux guest driver does not trigger the bug, probably due to a
    different buffer management strategy.
    Reported-by: NOliver Francke <oliver.francke@filoo.de>
    Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>
    00b7ade8
rtl8139.c 101.4 KB