David Miller <davem@xxxxxxxxxxxxx> writes: > From: ebiederm@xxxxxxxxxxxx (Eric W. Biederman) > Date: Tue, 11 Mar 2014 13:48:01 -0700 > >> To play devil's advocate to my own patch. Does anyone know where kgdb >> over network (kgdboe) code lives today? >> >> What little I could find in a quick google search strongly suggests that >> kgdboe was abandoned in 2010 or so. >> >> I am trying to figure out if there are any active out of tree projects >> that need by directional netpoll. > > Good questions. > > I, perhaps mistakenly, kept the functionality around because there > were claims that we'd use it in-tree. > > That of course never materialized. > > The fact that people have a lot of trouble even finding the kgdboe > sources is quite telling, indeed. Also telling is that we actually broken kgdboe support in 2011 when netpoll_poll was removed. > Let's kill it, we can pull it back in (perhaps with a better design) > if something is proposed in-tree that will need it. Sounds good. Patches to follow shortly. > But I'm skeptical we ever will need it, and even if such a > reinstatement is proposed f.e. for the kgdboe use case it has holes. > > Consider the case where kgdboe takes a breakpoint in a hardware > interrupt handler. What happens? We cannot allow it to perform a > full back-and-forth conversation with the remote gdb from such a > context. In interests of full disclosure I missed a subtle detail, and what the code does today is that when netpoll_poll_dev is running is that it intercepts and drops all in-coming packets. So I think the current packet receive design might be salvaged, if someone gets interested again. The bitrot is pretty significant currently. Still I should point out that the code that drops received skbs is technically wrong today. It uses kfree_skb, instead of the needed dev_kfree_skb_any that is needed to work in any context netpoll_rx might be called in. Eric -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html