[RHEL5.6] Kernel panic in cciss_softirq_done after sg_turs with CCISS driver

Issue

• Using an updated device-mapper-multipath to enable CCISS support causes kernel crash in cciss_softirq_done

• Kernel panics when issuing the Test Unit Ready command (sg_turs utility) on a device attached to a CCISS controller with a backtrace similar to this one:

  Unable to handle kernel NULL pointer dereference at 0000000000000030
  Pid: 0, comm: swapper Not tainted 2.6.18-236.el5 #1
  RIP: 0010:[<ffffffff880b94fc>]  [<ffffffff880b94fc>]:cciss:cciss_softirq_done+0xea/0x36d
  Call Trace:
   <IRQ>  [<ffffffff880bc1c9>] :cciss:do_cciss_intr+0xaab/0xae8
   [<ffffffff80037e5a>] blk_done_softirq+0x5f/0x6d
   [<ffffffff80012464>] __do_softirq+0x89/0x133
   [<ffffffff8005e2fc>] call_softirq+0x1c/0x28
   [<ffffffff8006d5f5>] do_softirq+0x2c/0x7d
   [<ffffffff8006d485>] do_IRQ+0xec/0xf5
  
  Code: 8b 57 30 74 0a 89 d5 81 e5 00 fe ff ff eb 07 41 8b ad dc 00 
  RIP  [<ffffffff880b94fc>] :cciss:cciss_softirq_done+0xea/0x36d