• Dexuan Cui's avatar
    vmbus: remove hv_event_tasklet_disable/enable · dad72a1d
    Dexuan Cui authored
    With the recent introduction of per-channel tasklet, we need to update
    the way we handle the 3 concurrency issues:
    
    1. hv_process_channel_removal -> percpu_channel_deq vs.
       vmbus_chan_sched -> list_for_each_entry(..., percpu_list);
    
    2. vmbus_process_offer -> percpu_channel_enq/deq vs. vmbus_chan_sched.
    
    3. vmbus_close_internal vs. the per-channel tasklet vmbus_on_event;
    
    The first 2 issues can be handled by Stephen's recent patch
    "vmbus: use rcu for per-cpu channel list", and the third issue
    can be handled by calling tasklet_disable in vmbus_close_internal here.
    
    We don't need the original hv_event_tasklet_disable/enable since we
    now use per-channel tasklet instead of the previous per-CPU tasklet,
    and actually we must remove them due to the side effect now:
    vmbus_process_offer -> hv_event_tasklet_enable -> tasklet_schedule will
    start the per-channel callback prematurely, cauing NULL dereferencing
    (the channel may haven't been properly configured to run the callback yet).
    
    Fixes: 631e63a9 ("vmbus: change to per channel tasklet")
    Signed-off-by: default avatarDexuan Cui <decui@microsoft.com>
    Cc: "K. Y. Srinivasan" <kys@microsoft.com>
    Cc: Haiyang Zhang <haiyangz@microsoft.com>
    Cc: Stephen Hemminger <sthemmin@microsoft.com>
    Tested-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
    Signed-off-by: default avatarK. Y. Srinivasan <kys@microsoft.com>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    dad72a1d
channel.c 25.5 KB