1. 10 Jun, 2017 4 commits
  2. 09 Jun, 2017 14 commits
  3. 08 Jun, 2017 21 commits
  4. 07 Jun, 2017 1 commit
    • David S. Miller's avatar
      net: Fix inconsistent teardown and release of private netdev state. · cf124db5
      David S. Miller authored
      Network devices can allocate reasources and private memory using
      netdev_ops->ndo_init().  However, the release of these resources
      can occur in one of two different places.
      
      Either netdev_ops->ndo_uninit() or netdev->destructor().
      
      The decision of which operation frees the resources depends upon
      whether it is necessary for all netdev refs to be released before it
      is safe to perform the freeing.
      
      netdev_ops->ndo_uninit() presumably can occur right after the
      NETDEV_UNREGISTER notifier completes and the unicast and multicast
      address lists are flushed.
      
      netdev->destructor(), on the other hand, does not run until the
      netdev references all go away.
      
      Further complicating the situation is that netdev->destructor()
      almost universally does also a free_netdev().
      
      This creates a problem for the logic in register_netdevice().
      Because all callers of register_netdevice() manage the freeing
      of the netdev, and invoke free_netdev(dev) if register_netdevice()
      fails.
      
      If netdev_ops->ndo_init() succeeds, but something else fails inside
      of register_netdevice(), it does call ndo_ops->ndo_uninit().  But
      it is not able to invoke netdev->destructor().
      
      This is because netdev->destructor() will do a free_netdev() and
      then the caller of register_netdevice() will do the same.
      
      However, this means that the resources that would normally be released
      by netdev->destructor() will not be.
      
      Over the years drivers have added local hacks to deal with this, by
      invoking their destructor parts by hand when register_netdevice()
      fails.
      
      Many drivers do not try to deal with this, and instead we have leaks.
      
      Let's close this hole by formalizing the distinction between what
      private things need to be freed up by netdev->destructor() and whether
      the driver needs unregister_netdevice() to perform the free_netdev().
      
      netdev->priv_destructor() performs all actions to free up the private
      resources that used to be freed by netdev->destructor(), except for
      free_netdev().
      
      netdev->needs_free_netdev is a boolean that indicates whether
      free_netdev() should be done at the end of unregister_netdevice().
      
      Now, register_netdevice() can sanely release all resources after
      ndo_ops->ndo_init() succeeds, by invoking both ndo_ops->ndo_uninit()
      and netdev->priv_destructor().
      
      And at the end of unregister_netdevice(), we invoke
      netdev->priv_destructor() and optionally call free_netdev().
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      cf124db5