Description of problem:
Segfault on startup when trying to monitor SCSI hard drives on AMD64
with smartd.

Version-Release number of selected component (if applicable):
# rpm -q kernel-utils
kernel-utils-2.4-8.37.3

How reproducible:
Every time.

Steps to Reproduce:
1. Set up an AMD64 machine with SCSI hard drives
2. Add "/dev/sda -a -m root.redhat.com" to
/etc/smartd.conf
3. launch "smartd -d", and see the crash.
  
The crash only occurs when smartd is compiled with -O2, and -O1, not
when compiled with -O0.

Backtrace with -O1:
scsidevicescan (devices=0x7fbffff3f0, cfg=0x0) at smartd.c:852
852     smartd.c: No such file or directory.
       in smartd.c
(gdb) bt
#0  scsidevicescan (devices=0x7fbffff3f0, cfg=0x0) at smartd.c:852
#1  0x0000000000405772 in main (argc=0, argv=0x0) at smartd.c:2175

It crashes as soon as it tries to access cfg->, as cfg is NULL, but
adding a 'printf ("%p\n", cfg);' says that cfg is not NULL...

Breakpoint Backtrace with -O0, as it doesn't crash with -O0:
Breakpoint 1, scsidevicescan (devices=0x7fbffff400, cfg=0x51cfa0)
   at smartd.c:758
758     smartd.c: No such file or directory.
       in smartd.c
(gdb) bt
#0  scsidevicescan (devices=0x7fbffff400, cfg=0x51cfa0) at smartd.c:758
#1  0x00000000004067e4 in main (argc=2, argv=0x7fbffff908) at
smartd.c:2183

I tried debugging with ElectricFence, both under- and overfencing, and
there don't seem to be any memory corruption issues.
I still don't understand why "cfg" would show up as NULL when compiled
with -O1, and non-NULL, with -O0, under gdb.

(Bear in mind that those sources were modified a bit when trying to
debug the problem, the crash actually occurs when accessing cfg->:
// record number of device, type of device, increment device count
cfg->tryata = 0;

I think it could be a compilation/optimisation problem.