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	Thu, 24 Apr 1997 05:17:48 -0400 (EDT)
From: Peter Dufault <dufault@hda.com>
Message-Id: <199704240917.FAA02943@hda.hda.com>
Subject: Re: Panic in sys/scsi/scsiconf.c - Please Help...
In-Reply-To: <XFMail.970423223607.Shimon@i-Connect.Net> from Simon Shapiro at "Apr 23, 97 10:25:18 pm"
To: Shimon@i-Connect.Net (Simon Shapiro)
Date: Thu, 24 Apr 1997 05:17:48 -0400 (EDT)
Cc: scsi@freebsd.org
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> I am calling scsi_attachdevs() from a device driver and getting PANIC:
> 
> extend_set: entry 1 already has storage
> panic:  scsi-attachdevs: malloc.
> 
> Upon close examination one sees the lines:
> 
> if(scbus == 0 || scbus->sc_link == 0
>            || extend_set(scbusses, scsibus, scbus) == 0) {
>                 panic("scsi_attachdevs: malloc");
> ...
> 

(That first "scbus == 0" isn't doing anything since it was just
dereferenced.)

Extend_set is allocating pointers in chunks, and reallocating and
moving them when it runs out of point space.  Then the array can be indexed
at run time instead of walking a data structure.

extend_set is panicing because it requires:

1. That the index (scsibus) not have already been set;
2. That newly allocated storage be zeroed.

We're probably violating rule 1.  I'm surprised you're on your
176th disk and just now getting to bus 1.  Is there a chance you
have two devices wired down to bus 1 and nothing complained?
Try boot verbose, and next time include your config output.

> us->sc_link == 0
>            || extend_set(scbusses, scsibus, scbus) == 0) {
>                 panic("scsi_attachdevs: malloc");

And as Justin asked, why do you always get repeated text at the
end of your messages?

Peter

-- 
Peter Dufault (dufault@hda.com)   Realtime Machine Control and Simulation
HD Associates, Inc.               Voice: 508 433 6936