BUG REPORT: terminal hangs when I load the sd_mod module

BUG REPORT: terminal hangs when I load the sd_mod module

[Chris Friesen]

I have a 2.6.0-test8 kernel with the jumpshot card reader.  I can
compile the generic scsi driver no problem, and when I insert the flash
card I get the following log entry:

Oct 20 23:23:02 doug kernel: hub 2-1:1.0: new USB device on port 2, 
assigned address 4
Oct 20 23:23:02 doug kernel: scsi1 : SCSI emulation for USB Mass Storage 
devices
Oct 20 23:23:02 doug kernel:   Vendor: Lexar     Model: Jumpshot USB CF 
   Rev: 0001
Oct 20 23:23:02 doug kernel:   Type:   Direct-Access 
   ANSI SCSI revision: 02

When I try and load the sd_mod module, that terminal just simply freezes
and I can't break out.  Similarly, if I compile scsi disk support right
into the kernel, it sits forever at boot time.  I have the following
options set in my .config.

#
# SCSI device support
#
CONFIG_SCSI=y
CONFIG_SCSI_PROC_FS=y

#
# SCSI support type (disk, tape, CD-ROM)
#
CONFIG_BLK_DEV_SD=m
# CONFIG_CHR_DEV_ST is not set
# CONFIG_CHR_DEV_OSST is not set
# CONFIG_BLK_DEV_SR is not set
CONFIG_CHR_DEV_SG=y

#
# Some SCSI devices (e.g. CD jukebox) support multiple LUNs
#
# CONFIG_SCSI_MULTI_LUN is not set
# CONFIG_SCSI_REPORT_LUNS is not set
CONFIG_SCSI_CONSTANTS=y
CONFIG_SCSI_LOGGING=y



This problem has been present since at least -test6.  Any ideas what's 
going on?

Thanks,
Chris

Re: BUG REPORT: terminal hangs when I load the sd_mod module

[Patrick Mansfield]

On Mon, Oct 20, 2003 at 11:30:49PM -0400, Chris Friesen wrote:

> When I try and load the sd_mod module, that terminal just simply freezes
> and I can't break out.  Similarly, if I compile scsi disk support right
> into the kernel, it sits forever at boot time.  I have the following
> options set in my .config.

> This problem has been present since at least -test6.  Any ideas what's 
> going on?

Maybe the MODE SENSE page cache is causing problems (known problem with
some USB storage devices), triggering the error (i.e. timeout) handler to
run, leading to the command being retried forever.

Turn on all scsi logging (you must be logging and booting over IDE, so
the following won't cause infinite logging):

sysctl -w dev.scsi.logging_level=0xffffffff

Also get a trace of the hung process via sysrq.

After you get that data, try removing sd_do_mode_sense() calls in sd.c to
see if MODE SENSE commands are causing problems.

You could also try using sg (sg_utils) to send a MODE SENSE page 8, and
see what happens.

-- Patrick Mansfield