Date: Tue, 29 Jun 2004 11:45:57 +0200
From: Kurt Garloff <garloff@suse.de>
To: Bart Hartgers <bart@etpmod.phys.tue.nl>
Cc: linux-kernel@vger.kernel.org
Subject: Re: hwscan hangs on USB2 disk - SCSI_IOCTL_SEND_COMMAND
Message-ID: <20040629094557.GR4732@tpkurt.garloff.de>
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	Bart Hartgers <bart@etpmod.phys.tue.nl>, linux-kernel@vger.kernel.org
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Hi Bart,

On Tue, Jun 29, 2004 at 11:37:36AM +0200, Bart Hartgers wrote:
> The problem is that both hwscan and usb-storage get stuck in the 'D"
> state until I unplug the harddisk.
>=20
> A strace of hwscan shows:
>=20
> 21141 open("/dev/sda", O_RDONLY|O_NONBLOCK) =3D 3
> 21141 ioctl(3, 0x301, 0xbfffeba0)       =3D 0
> 21141 ioctl(3, BLKSSZGET, 0xbfffeb9c)   =3D 0
> 21141 ioctl(3, 0x80041272, 0xbfffeb90)  =3D 0
> 21141 ioctl(3, FIBMAP, 0xbfffec40)      =3D 0  <--- hwscan gets stuck here
>=20
> The last ioctl corresponds to this bit of code in
> hwinfo-8.38/src/hd/block.c:
>=20
> #ifndef SCSI_IOCTL_SEND_COMMAND
> #define SCSI_IOCTL_SEND_COMMAND 1
> #endif
>=20
> ...
>=20
>       memset(scsi_cmd_buf, 0, sizeof scsi_cmd_buf);
>       // ###### FIXME: smaller!
>       *((unsigned *) (scsi_cmd_buf + 4)) =3D sizeof scsi_cmd_buf - 0x100;
>       scsi_cmd_buf[8 + 0] =3D 0x12;
>       scsi_cmd_buf[8 + 1] =3D 0x01;
>       scsi_cmd_buf[8 + 2] =3D 0x80;
>       scsi_cmd_buf[8 + 4] =3D 0xff;
>=20
>       k =3D ioctl(fd, SCSI_IOCTL_SEND_COMMAND, scsi_cmd_buf);
>=20
> So it appears that the driver hangs because of a SCSI command. Is this
> kernel bug, and if so, where do I fix it?

To me it looks like a bug in the USB stick.
It probably locks up when you ask for VPD page 0x80 (serial number)
of the device with INQUIRY.=20
Some shitty USB devices lock up when you ask for more than 36 bytes
with INQUIRY. See code in scsi_scan.c and the BLIST_INQUIRY_36 and
_58 flags.
Your device may even do so when you don't ask for standard INQUIRY=20
data but for EVPD page 0x80 :-(

Does it work if you send the INQUIRY with 36 bytes allocation length?
scsi_cmd_buf[8 + 4] =3D 0x26;
--=20
Kurt Garloff  <garloff@suse.de>                            Cologne, DE=20
SUSE LINUX AG / Novell, Nuernberg, DE               Director SUSE Labs

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