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Date: Thu, 13 Dec 2001 23:31:50 +0100
From: ki@kretz.co.at
To: linux-kernel@vger.kernel.org
Subject: 2.4.17pre2: ieee1394 sd hotplug problems (Oops)
Message-ID: <20011213233150.A8628@boss.kretz.co.at>
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Hello all,

I am using an 80GB ide disk together with an 
ide <> firewire converter card. (Oxford chip)

usually I am doing the following: (no SCSI hd present but sd_mod loaded)

 * connect & power on hd
 * insmod ieee1394, ohci1394 and sbp2
 * look for the partition info in the syslog, looks like this:

Dec 13 20:24:29 ki_pc2 kernel: scsi0 : IEEE-1394 SBP-2 protocol driver
Dec 13 20:24:29 ki_pc2 kernel:   Vendor: MAXTOR 4  Model: K080H4            Rev:     
Dec 13 20:24:29 ki_pc2 kernel:   Type:   Direct-Access                      ANSI SCSI revision: 06
Dec 13 20:24:29 ki_pc2 kernel: Attached scsi disk sdd at scsi0, channel 0, id 0, lun 0
Dec 13 20:24:29 ki_pc2 kernel: SCSI device sdd: 156301487 512-byte hdwr sectors (80026 MB)
Dec 13 20:24:29 ki_pc2 kernel:  sdd: sdd1
Dec 13 20:24:58 ki_pc2 /sbin/hotplug: no runnable /etc/hotplug/ieee1394.agent is installed

note: sdd,  not sda as expected

 * use the disk - works ok, hdparm says  ~12MB/sec
 * rmmod sbp2 (and perhaps also the other 1394 modules) 
 * disconnect hard drive.
 etc..

The following happens: on  'insmod sbp2' the disk is found
but the minor device is incremented every time (now I am at /dev/sde :-( )

Trying to open one of the lower (non-present) minors results in an Oops:

in sd.c: at about line 470
        }
        /*
         * The following code can sleep.
         * Module unloading must be prevented
         */
        SDev = rscsi_disks[target].device;

	^^^^^ this becomes zero for the lower minor devices.

        if (SDev->host->hostt->module) ---- Oops

So it seems that the rmmod sbp2 does not properly clean up
the internal bookkeeping in sd.c when being unloaded.

I am not sure what happens if scsi-remove-single-device is done instead
of rmmod sbp2.

OTOH /proc/scsi/scsi correctly shows the present devices
 
there are a few /dev/sd[a-?]  left so I dont have to reboot every time but
the situation is a bit non-optimal for now.

Greetings,
karl

-- 
Karl Kiniger	    ki@kretz.co.at
Kretztechnik AG     OE5KVN
Tiefenbach 15
A-4871 Zipf	    Tel: (++43) 7682-3800-710  Fax (++43) 7682-3800-47