Date: Thu, 04 Jun 1998 12:16:35 -0400 (EDT) From: Simon Shapiro <shimon@simon-shapiro.org> To: Greg Lehey <grog@lemis.com> Cc: Michael Hancock <michaelh@cet.co.jp>, "freebsd-current@freebsd.org" <freebsd-current@FreeBSD.ORG>, tcobb <tcobb@staff.circle.net>, Karl Pielorz <kpielorz@tdx.co.uk>, Bob Willcox <bob@luke.pmr.com>, Mike Smith <mike@smith.net.au> Subject: Re: DPT driver fails and panics with Degraded Array Message-ID: <XFMail.980604121635.shimon@simon-shapiro.org> In-Reply-To: <19980604095717.A22406@freebie.lemis.com>
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On 04-Jun-98 Greg Lehey wrote:
...
>>> I had to put some pretty ugly validity checks in the interrupt code to
>>> prevent my driver from trying to do an iodone (AIX's version of
>>> biodone)
>>> on already completed (or purged, I don't remember for sure...its been
>>> over a year now) commands. Seems that the DPT firmware would (on
>>> occasion) interrupt with a status packet that pointed to a ccb that my
>>> driver had already completed. As I recall this would only happen under
>>> heavy load and it was pretty intermittant. As far as I know, it was
>>> never actually fixed.
>>
>> Actually, this is *extremely* relevant, if the firmware is still doing
>> it and the DPT driver isn't aware of this.
>
> This would normally cause a 'biodone: buffer already done' message,
> which is a warning, not a panic. The only way I could think of this
> happening on a valid buffer (apart from the obvious of calling it
> while it wasn't busy) would be if something messed around with other
> buffer flags. I haven't been following this thread very
> carefully--were the panics associated with SMP only? If so, how is
> mutual exclusion performed in the bottom half of SMP drivers?
Actually this is a 2.2 (UP :-) problem. Not a 3.0, and not an SMP for sure.
Actually, SMP interrupt service is slow enough that this probably never has
a chance to show at all.
Simon
(We are getting about 2/3 the interrupts/sec under SMP. Last we checked
which was about 2 months ago).
---
Sincerely Yours,
Simon Shapiro Shimon@Simon-Shapiro.ORG
770.265.7340
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