Date: Thu, 2 Dec 1999 17:01:20 +0100 (CET) From: Nick Hibma <hibma@skylink.it> To: Doug Rabson <dfr@nlsystems.com> Cc: FreeBSD Newbus Mailing List <new-bus@FreeBSD.org> Subject: Re: PCCARD eject freeze (was Re: your mail) Message-ID: <Pine.BSF.4.20.9912021651490.2349-100000@henny.jrc.it> In-Reply-To: <Pine.BSF.4.10.9912012001260.325-100000@salmon.nlsystems.com>
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> > device_detach deletes the softc allocated for the device. > > Drivers cache copies of softc in their ISRs and other places where > > they sleep and count on the cached copy of softc to still be around > > when they are woken up. If a pccard is ejected between these points, > > these cached copies disappear because the ejection code deletes the > > device from the device tree (an as a side effect calls detach, which > > frees the softc for the device). > > > > Suspend has a similar problem because it can come in while a > > device is sleeping. > > The device_detach routine *must* teardown all interrupt handlers and > release all resources. If this rule is followed, then the handler > shouldn't be called after detach, so there is no problem, right? The problem is that the following occurs now: DEVICE_DETACH called from device_delete_child wakes up all the sleepers and exits. The sleepers actually start running after DEVICE_DETACH has finished and the softc has been blown away by the device_delete_child that followed. I think this cries for a loop: Call detach and if EAGAIN is returned make sure sleepers can wake up and exit, and then try again. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ I have no idea how this 'wait for sleepers to have run' could be implemented, but this is I think the crucial part. Nick -- hibma@skylink.it n_hibma@freebsd.org USB project http://www.etla.net/~n_hibma/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-new-bus" in the body of the message
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