On Mon, Feb 15, 2016 at 6:35 PM, Roy Marples <r...@marples.name> wrote: > On 15/02/2016 08:08, Ryota Ozaki wrote: >> Module Name: src >> Committed By: ozaki-r >> Date: Mon Feb 15 08:08:04 UTC 2016 >> >> Modified Files: >> src/sys/net: if.c if.h >> >> Log Message: >> Run if_link_state_change in softint >> >> if_link_state_change can execute the network stack that is expected to >> not run in hardware interrupt (at least now), however network drivers >> may call it in hardware interrupt. Avoid that by introducing a new >> softint for if_link_state_change. > > I don't know anything about softints, so this could be a silly question, > but this change looks racey to me. Is there a guarantee anywhere that > if_link_state_change() won't be called again before > if_link_state_change_si() has been called?
Not guaranteed. Hmm, you're right. There is a race condition; ifp->if_link_state can be overwritten before calling if_link_state_change_si and it does matter if ifp->if_link_state has been back to ifp->if_old_link_state. (If ifp->if_link_state is different from ifp->if_old_link_state, it doesn't matter because it's just that the later state wins.) I think we can fix by returning from if_link_state_change_si if ifp->if_link_state == ifp->if_old_link_state. Is it correct? Thanks, ozaki-r
