[SCSI] hpsa: fix a race in cmd_free/scsi_done

When the driver calls scsi_done and after that frees it's internal
preallocated memory it can happen that a new job is enqueud before
the memory is freed. The allocation fails and the message
"cmd_alloc returned NULL" is shown.
Patch below fixes it by moving cmd->scsi_done after cmd_free.

Signed-off-by: Tomas Henzl <thenzl@redhat.com>
Acked-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

drivers/scsi/hpsa.c

@@ -1205,8 +1205,8 @@ static void complete_scsi_command(struct CommandList *cp)
 	scsi_set_resid(cmd, ei->ResidualCnt);
 
 	if (ei->CommandStatus == 0) {
-		cmd->scsi_done(cmd);
 		cmd_free(h, cp);
+		cmd->scsi_done(cmd);
 		return;
 	}
 
@@ -1379,8 +1379,8 @@ static void complete_scsi_command(struct CommandList *cp)
 		dev_warn(&h->pdev->dev, "cp %p returned unknown status %x\n",
 				cp, ei->CommandStatus);
 	}
-	cmd->scsi_done(cmd);
 	cmd_free(h, cp);
+	cmd->scsi_done(cmd);
 }
 
 static void hpsa_pci_unmap(struct pci_dev *pdev,