From: gfree.w...@foxmail.com Date: Tue, 2 May 2017 13:58:42 +0800 > These following drivers allocate kinds of resources in its ndo_init > func, free some of them or all in the destructor func. Then there is > one memleak that some errors happen after register_netdevice invokes > the ndo_init callback. Because only the ndo_uninit callback is invoked > in the error handler of register_netdevice, but destructor not. > > In my original approach, I tried to free the resources in the newlink > func when fail to register_netdevice, like destructor did except not > free the net_dev. This method is not good when destructor is changed, > and the memleak could be not fixed when there is no newlink callback. > > Now create one new func used to free the resources in the destructor, > and the ndo_uninit func also could invokes it when fail to register > the net_device by comparing the dev->reg_state with NETREG_UNINITIALIZED. > If there is no existing ndo_uninit, just add one. > > This solution doesn't only make sure free all resources in any case, > but also follows the original desgin that some resources could be kept > until the destructor executes normally after register the device > successfully.
I want to think about this some more. It is really unfortunate that resources are allocated strictly from the ndo_init() yet released in two different callbacks which are invoked only in certain (different) situations. Just the fact that we have to make an internal netdev state test in the ndo_uninit callback to get this right is a big red flag to me.
