Date: Mon, 22 Oct 2012 12:08:37 +0200 From: Marko Zec <zec@fer.hr> To: Adrian Chadd <adrian@freebsd.org> Cc: freebsd-net@freebsd.org, freebsd-hackers@freebsd.org Subject: Re: VIMAGE crashes on 9.x with hotplug net80211 devices Message-ID: <201210221208.37592.zec@fer.hr> In-Reply-To: <CAJ-VmokH2VqK-5of2%2B79mKbQ9m61tTvdqCCSJkj3EPejmDaH=A@mail.gmail.com> References: <CAJ-VmomchJZ7GUKrAjmmyBXDw-6H6O5fAxT_tfAFfhU=HknG1g@mail.gmail.com> <201210212322.48791.zec@fer.hr> <CAJ-VmokH2VqK-5of2%2B79mKbQ9m61tTvdqCCSJkj3EPejmDaH=A@mail.gmail.com>
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On Monday 22 October 2012 01:03:19 Adrian Chadd wrote: ... > > Obviously, handling device attach events is an exception from this > > rule, and up to this date this was never properly addressed... > > *laugh*. > > The problem now is figuring out how to do it without modifying all the > drivers. > > The attach is easy - I can likely set it up during the device_attach() > pass. I can do that, but it's enforcing "networking-ness" with the > device attach, which will be called for networking and non-networking > devices alike. > > However detach isn't easy - because I'm required to call > CURVNET_SET(ifp->if_vnet) and CURVNET_RESTORE() around if_free(), and > if_free() is called in the device specific detach() routine, I can't > easily set the current VNET context from outside the driver. > > I _guess_ I could device_attach() to use CURVNET_SET(vnet0) but > device_detach() can't do the same - it doesn't "know" about the > networking-ness of the device. > > I'm open to other suggestions. The only option I can think of now is to update all of the hotunpluggable device_detach() handlers to do CURVNET_SET(ifp->if_vnet) before calling further down into the networking stack, because as you already observed, whatever triggers a device_detach() handler is not aware of the nature of the driver. > (how the hell does this work for devices attached at probe time? What > vnet context do they have, and why doesn't the kernel panic there?) Because at boot / autoconfiguration time curvnet is implicitly set to vnet0 between SI_SUB_VNET and SI_SUB_VNET_DONE (i.e. before going SMP). Similarly, curvnet is set to vnet0 during kldload events. Marko
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