• Xin Long's avatar
    xfrm: reuse uncached_list to track xdsts · 510c321b
    Xin Long authored
    In early time, when freeing a xdst, it would be inserted into
    dst_garbage.list first. Then if it's refcnt was still held
    somewhere, later it would be put into dst_busy_list in
    dst_gc_task().
    
    When one dev was being unregistered, the dev of these dsts in
    dst_busy_list would be set with loopback_dev and put this dev.
    So that this dev's removal wouldn't get blocked, and avoid the
    kmsg warning:
    
      kernel:unregister_netdevice: waiting for veth0 to become \
      free. Usage count = 2
    
    However after Commit 52df157f ("xfrm: take refcnt of dst
    when creating struct xfrm_dst bundle"), the xdst will not be
    freed with dst gc, and this warning happens.
    
    To fix it, we need to find these xdsts that are still held by
    others when removing the dev, and free xdst's dev and set it
    with loopback_dev.
    
    But unfortunately after flow_cache for xfrm was deleted, no
    list tracks them anymore. So we need to save these xdsts
    somewhere to release the xdst's dev later.
    
    To make this easier, this patch is to reuse uncached_list to
    track xdsts, so that the dev refcnt can be released in the
    event NETDEV_UNREGISTER process of fib_netdev_notifier.
    
    Thanks to Florian, we could move forward this fix quickly.
    
    Fixes: 52df157f ("xfrm: take refcnt of dst when creating struct xfrm_dst bundle")
    Reported-by: default avatarJianlin Shi <jishi@redhat.com>
    Reported-by: default avatarHangbin Liu <liuhangbin@gmail.com>
    Tested-by: default avatarEyal Birger <eyal.birger@gmail.com>
    Signed-off-by: default avatarXin Long <lucien.xin@gmail.com>
    Signed-off-by: default avatarSteffen Klassert <steffen.klassert@secunet.com>
    510c321b
route.h 10 KB