Date: Wed, 22 Feb 2006 04:22:01 +0000 (GMT) From: Nate Nielsen <nielsen-list@memberwebs.com> To: Ian Dowse <iedowse@iedowse.com> Cc: freebsd-hackers@freebsd.org, Scott Long <scottl@samsco.org> Subject: Re: Panic Kernel Dump to umass device? Message-ID: <20060222042200.BC7B3DCAA07@mail.npubs.com> References: <200602111542.aa07502@nowhere.iedowse.com>
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Ian Dowse wrote:
> In message <43ED8E81.2060907@samsco.org>, Scott Long writes:
>
>>You're correct that dumping is meant to be done with interrupts and task
>>switching disabled. The first thing that the umass driver is missing is
>>a working CAM poll handler. Without this, there is no way for command
>>completions to be seen when interrupts are disabled. Beyond that, I
>>somewhat suspect that the USB stack expects to be able to push command
>>completion work off to worker threads, at least for some situations, and
>>that also will not work in the kernel dump environment. So, there is a
>>lot of work needed to make this happen.
>
>
> The USB stack supports polled operations, so it's actually not to
> hard to make this work. Below is a patch I had in one of my local
> trees that adds a CAM poll handler to the umass driver. I've just
> tested this and it does seem to make kernel dumping work, but I
> guess it might not be as reliable as dumping to other devices.
As noted earlier the umass polling patch you posted works for dumping to
a umass device via a uhci controller.
After a little more fiddling I've managed to get it working on an ohci
controller. Attached is a patch. This patch includes your patch above.
Cheers,
Nate
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Index: sys/dev/usb/umass.c
===================================================================
RCS file: /home/ncvs/src/sys/dev/usb/umass.c,v
retrieving revision 1.122.2.6
diff -U3 -r1.122.2.6 umass.c
--- sys/dev/usb/umass.c 29 Jan 2006 00:45:11 -0000 1.122.2.6
+++ sys/dev/usb/umass.c 22 Feb 2006 03:04:02 -0000
@@ -2643,21 +2643,17 @@
}
}
-/* umass_cam_poll
- * all requests are handled through umass_cam_action, requests
- * are never pending. So, nothing to do here.
- */
Static void
umass_cam_poll(struct cam_sim *sim)
{
-#ifdef USB_DEBUG
struct umass_softc *sc = (struct umass_softc *) sim->softc;
DPRINTF(UDMASS_SCSI, ("%s: CAM poll\n",
USBDEVNAME(sc->sc_dev)));
-#endif
- /* nop */
+ usbd_set_polling(sc->sc_udev, 1);
+ usbd_dopoll(sc->iface);
+ usbd_set_polling(sc->sc_udev, 0);
}
Index: sys/dev/usb/ohci.c
===================================================================
RCS file: /home/ncvs/src/sys/dev/usb/ohci.c,v
retrieving revision 1.154.2.2
diff -U3 -r1.154.2.2 ohci.c
--- sys/dev/usb/ohci.c 29 Jan 2006 01:26:46 -0000 1.154.2.2
+++ sys/dev/usb/ohci.c 22 Feb 2006 03:04:05 -0000
@@ -3049,6 +3049,9 @@
splx(s);
+ if (sc->sc_bus.use_polling)
+ ohci_waitintr(sc, xfer);
+
return (USBD_IN_PROGRESS);
}
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