• Vitaly Kuznetsov's avatar
    netvsc: get rid of completion timeouts · 5362855a
    Vitaly Kuznetsov authored
    I'm hitting 5 second timeout in rndis_filter_set_rss_param() while setting
    RSS parameters for the device. When this happens we end up returning
    -ETIMEDOUT from the function and rndis_filter_device_add() falls back to
    setting
    
            net_device->max_chn = 1;
            net_device->num_chn = 1;
            net_device->num_sc_offered = 0;
    
    but after a moment the rndis request succeeds and subchannels start to
    appear. netvsc_sc_open() does unconditional nvscdev->num_sc_offered-- and
    it becomes U32_MAX-1. Consequent rndis_filter_device_remove() will hang
    while waiting for all U32_MAX-1 subchannels to appear and this is not
    going to happen.
    
    The immediate issue could be solved by adding num_sc_offered > 0 check to
    netvsc_sc_open() but we're getting out of sync with the host and it's not
    easy to adjust things later, e.g. in this particular case we'll be creating
    queues without a user request for it and races are expected. Same applies
    to other parts of the driver which have the same completion timeout.
    
    Following the trend in drivers/hv/* code I suggest we remove all these
    timeouts completely. As a guest we can always trust the host we're running
    on and if the host screws things up there is no easy way to recover anyway.
    Signed-off-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
    Acked-by: default avatarHaiyang Zhang <haiyangz@microsoft.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    5362855a
netvsc.c 34.6 KB