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Date: Tue, 26 Jun 2012 20:29:09 -0600
From: "Kenneth D. Merry" <ken@freebsd.org>
To: Michael Butler <imb@protected-networks.net>
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Cc: Benjamin Kaduk <kaduk@mit.edu>, current@freebsd.org
Subject: Re: Removing an SDHC card causes a kernel panic on -current
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On Tue, Jun 26, 2012 at 19:41:07 -0400, Benjamin Kaduk wrote:
> On Tue, 26 Jun 2012, Michael Butler wrote:
> 
> >As follows, in "g_disk_providergone", a NULL pointer reference?:
> 
> g_disk_providergone() is new in r237518 (by ken); ken cc'd.

Can you try the attached patch to sys/geom/geom_disk.c?

Also, do you have full dmesg information for when the panic happened?

It looks like disk_destroy() has already been called in this case, and I
suppose that's likely to happen for any of the users of the GEOM disk class
that haven't been updated with the reference count changes I made in da(4).
(i.e. all of the rest of them.)

Let me know whether this works for you.

Thanks,

Ken
-- 
Kenneth Merry
ken@FreeBSD.ORG

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==== //depot/users/kenm/FreeBSD-test2/sys/geom/geom_disk.c#7 - /usr/home/kenm/perforce4/kenm/FreeBSD-test2/sys/geom/geom_disk.c ====
*** /tmp/tmp.75357.20	Tue Jun 26 20:25:44 2012
--- /usr/home/kenm/perforce4/kenm/FreeBSD-test2/sys/geom/geom_disk.c	Tue Jun 26 20:25:29 2012
***************
*** 502,507 ****
--- 502,515 ----
  	struct g_disk_softc *sc;
  
  	sc = (struct g_disk_softc *)pp->geom->softc;
+ 
+ 	/*
+ 	 * If the softc is already NULL, then we've probably been through
+ 	 * g_disk_destroy already; there is nothing for us to do anyway.
+ 	 */
+ 	if (sc == NULL)
+ 		return;
+ 
  	dp = sc->dp;
  
  	if (dp->d_gone != NULL)

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