We need scsi_add_host sometimes without having a struct device (i.e.
eisa/vlb drivers, ieee1394 storage), so handle that case gracefully.

into mulgrave.(none):/home/jejb/BK/scsi-misc-new-2.5

- change the eh_notify semaphore to a completion
- add complete_and_exit() to the thread
- use a host structure flag to signal thread death instead of the signal

I earlier reported, that the error handler for ide-scsi exits prematurely if modprobed
from rc.sysinit. I put in some debug prints to apprehend the culprit responsible for
sending the SIGHUP signal that causes the exit.

This is what my log captured:

Jan  1 12:20:13 fallguy kernel: Process 223 [modprobe] starting scsi error handler
Jan  1 12:20:13 fallguy kernel: Wake up parent of scsi_eh_2, pid 224
Jan  1 12:20:13 fallguy kernel: Signals pending for scsi_eh_2: 00000000 00000000
Jan  1 12:20:13 fallguy kernel: Error handler scsi_eh_2 sleeping
Jan  1 12:20:13 fallguy kernel: scsi2 : SCSI host adapter emulation for IDE ATAPI devices
[detected devices skipped]
Jan  1 12:20:14 fallguy kernel: Signal 15 sent from 181 [rc.sysinit] to 182 [getkey]
Jan  1 12:20:14 fallguy kernel: Signal 1 sent from 22 [init] to 22 [init]
Jan  1 12:20:14 fallguy kernel: Signal 18 sent from 22 [init] to 22 [init]
Jan  1 12:20:14 fallguy kernel: Signal 1 sent from 22 [init] to 22 [init]
Jan  1 12:20:14 fallguy kernel: Signal 1 sent from 22 [init] to 24 [initlog]
Jan  1 12:20:14 fallguy kernel: Signal 1 sent from 22 [init] to 78 [khubd]
Jan  1 12:20:14 fallguy kernel: Signal 1 sent from 22 [init] to 224 [scsi_eh_2]
Jan  1 12:20:14 fallguy kernel: Signals pending for scsi_eh_2: 00000001 00000000
Jan  1 12:20:14 fallguy kernel: Error handler scsi_eh_2 exiting

Here is a snapshot of some processes made during rc.sysinit:

  F   UID   PID  PPID PRI  NI   VSZ  RSS WCHAN  STAT TTY        TIME COMMAND
100     0     1     0  15   0  1332  420 schedu S    ?          0:05 init
...
040     0    22     1  16   0  1332  388 wait4  S    tty1       0:00 init
000     0    23    22  15   0  4116 1316 wait4  S    tty1       0:00 /bin/bash /
040     0    24    23  16   0  2160 1364 schedu S    tty1       0:00 /sbin/initl
...

Init must have forked to exec bash to exec rc.sysinit which then gets re-executed
through initlog. When rc.sysinit ends, the last thing it does is send that TERM
signal from sub-process 181 to getkey (process 182) -- the 'Signal 15 ...' line 
above.

As the forked init (process 22) exits, it sends a flurry of signals to all surviving
processes created from it. That looks like standard "if I am to die I need to take
all my offspring down with me" behavior -- do you agree?

Since we want error handlers to survive, IMHO that means that the choice of signal
for error handler exit is unfortunate. The source of scsi_error suggests SIGPWR
might be a worthy alternative. I think that is true. From inspecting init source,
it is not capable of sending SIGPWR. SIGPWR should never be sent by dying processes
(its sole use should be from a power daemon _to_ init to shut the system down when
the juice is running out).

So I suggest the following changes to hosts.c and scsi_error.c:

Hi -

This simple patch adds scsi_level to the scsi_device sysfs attributes,
mainly for use with Doug Gilbert's lsscsi program.

The attachment modifies the SG_IO ioctl that is in
the block layer to:
   - convey the SCSI status value back via the sg_io_hdr
     structure
   - in the event of CHECK CONDITION, convey the sense
     buffer back via the sg_io_hdr structure
   - set "output" fields in sg_io_hdr structure to sane
     values
   - modify the errno behaviour to be more like the
     SCSI generic driver's SG_IO ioctl

This patch was presented around lk 2.5.51 but fell between
the cracks. The only modification is to take account of
the changes to scsi/scsi_lib.c since then.

into home.transmeta.com:/home/torvalds/v2.5/linux

into tetrachloride.(none):/mnt/stuff/kernel/2.5/watchdog

into tetrachloride.(none):/mnt/stuff/kernel/2.5/watchdog

into home.transmeta.com:/home/torvalds/v2.5/linux

into tetrachloride.(none):/mnt/stuff/kernel/2.5/agpgart

version before looking at more complicated changes.