[SCSI] fix oops on usb storage device disconnect

We fix the oops by enforcing the host state model.  There have also
been two extra states added: SHOST_CANCEL_RECOVERY and
SHOST_DEL_RECOVERY so we can take the model through host removal while
the recovery thread is active.

Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index a780546..1f0ebab 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -1265,9 +1265,8 @@
 		list_for_each_safe(lh, lh_sf, &active_list) {
 			scmd = list_entry(lh, struct scsi_cmnd, eh_entry);
 			list_del_init(lh);
-			if (recovery) {
-				scsi_eh_scmd_add(scmd, SCSI_EH_CANCEL_CMD);
-			} else {
+			if (recovery &&
+			    !scsi_eh_scmd_add(scmd, SCSI_EH_CANCEL_CMD)) {
 				scmd->result = (DID_ABORT << 16);
 				scsi_finish_command(scmd);
 			}