On Fri, 22 Mar 2024 07:58:02 -0700 Breno Leitao wrote: > > Looks like init_dummy_netdev wipes the netdev structure clean, so I > > don't think we can use it directly as the setup function, Breno :( > > Before my patch, init_dummy_netdev was being also used. The patch was > basically replacing the init_dummy_netdev by alloc_netdev() with will > call "setup(dev);" later. > > - init_dummy_netdev(&irq_grp->napi_ndev); > + irq_grp->napi_ndev = alloc_netdev(0, "dummy", NET_NAME_UNKNOWN, > + init_dummy_netdev); > > I am wondering if alloc_netdev() is messing with something instead of > init_dummy_netdev(). alloc_netdev() allocates some memory and initializes lists which free_netdev() wants to free, basically. But init_dummy_netdev() does: /* Clear everything. Note we don't initialize spinlocks * are they aren't supposed to be taken by any of the * NAPI code and this dummy netdev is supposed to be * only ever used for NAPI polls */ memset(dev, 0, sizeof(struct net_device)); so all those pointers and init alloc_netdev() did before calling setup will get wiped. > Also, Kalle's crash is during rmmod, and not during initialization. > getting NULL after free_netdev() is called. > > > Maybe we should add a new helper to "alloc dummy netdev" which can > > call alloc_netdev() with right arguments and do necessary init? > > What are the right arguments in this case? I'm not sure we have a noop setup() callback today. If you define a wrapper to allocate a dummy netdev you can define a new empty function next to it and pass that as init? Hope I got the question right.
