Hi Sven, synchronize_net already contains a synchronize_rcu at its end, so the synchronize_rcu in the batman code there has always been redundant.
I've removed the synchronize_rcu instead of the synchronize_net to be on the safe side. I guess usually no more packets should arrive anyway as the batman packet type is not registered anymore. But I wasn't sure if the might_sleep() of synchronize_net() might be needed for something, so I didn't dare to remove synchronize_net. If someone says it'd be ok to remove synchronize_net() instead, I could make a new patch, no problem. Cheers, Linus On Mon, Sep 06, 2010 at 09:30:46AM +0200, Sven Eckelmann wrote: > On Mon, Sep 06, 2010 at 01:29:53AM +0200, Linus Lüssing wrote: > > During the module shutdown procedure in batman_exit(), a rcu callback is > > being scheduled (batman_exit -> hardif_remove_interfaces -> > > hardif_remove_interfae -> call_rcu). However, when the kernel unloads > > the module, the rcu callback might not have been executed yet, resulting > > in a "unable to handle kernel paging request" in __rcu_process_callback > > afterwards, causing the kernel to freeze. > > Therefore, we should always flush all rcu callback functions scheduled > > during the shutdown procedure. > > I am really irritated by your patch. I would have expected that you add a > synchronyze_rcu in batman_exit and that was it. Instead I see a > synchronize_net > added and a synchronize_net/-_rcu removed from mesh_free. This doesn't seem to > match at all. Could you please explain further why it is implemented that way? > > thanks, > Sven
