Panic with sym on 10.2

[Marius Strobl]

On Tue, Jan 19, 2016 at 03:39:55PM +0100, Andrea Venturoli wrote:
> On 01/19/16 15:19, Matthew Seaman wrote:
> > On 01/19/16 13:13, Andrea Venturoli wrote:
> >> Two days ago I upgraded a (perfectly working) 9.3/i386 box to 10.2p10
> >> Since then I've had two panics with the following message:
> >>
> >> panic: assertion "lp->busy_itl==0&&lp->busy_itlq==0" failed: file
> >> /usr/src/sys/dev/sym/sym_hipd.c
> >>
> >> Since the disk controller is involved, I do not get any core and I have
> >> to press the reset button.
> >>
> >> Google showed up no results (I'm not using ZFS, btw) and Bugzilla didn't
> >> help either.
> >>

These debugging assertions in sym_get_ccb() probably can just be
replaced with graceful handling (see the attached patch). I'm
unsure whether it's sufficient to tell the CAM stack to retry at
a later point, though, and given I'm not hitting this problem I
also can't test. Unlike SCSI-2, SCSI-3 generally allows to mix a
single untagged command with tagged ones (the situation you are
encountering), which FreeBSD apparently started doing somewhere
between 9.3 and 10.2. However, permitting that would require a
careful review of sym(4) and most likely larger changes.

Marius

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