[SCSI] 3w-xxxx: scsi_dma_unmap fix

This patch fixes the following regression that occurred during the
scsi_dma_map()/unmap()
changes when compiling with CONFIG_DMA_API_DEBUG=y :

WARNING: at lib/dma-debug.c:496 check_unmap+0x142/0x542()
Hardware name:
3w-xxxx 0000:02:02.0: DMA-API: device driver tries to free DMA memory
it has not allocated [device address=0x0000000000000000] [size=36
bytes]
Signed-off-by: Adam Radford <aradford@gmail.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

drivers/scsi/3w-xxxx.c

@@ -6,7 +6,7 @@
    		     Arnaldo Carvalho de Melo <acme@conectiva.com.br>
                      Brad Strand <linux@3ware.com>
 
-   Copyright (C) 1999-2007 3ware Inc.
+   Copyright (C) 1999-2009 3ware Inc.
 
    Kernel compatiblity By: 	Andre Hedrick <andre@suse.com>
    Non-Copyright (C) 2000	Andre Hedrick <andre@suse.com>
@@ -1294,7 +1294,8 @@ static void tw_unmap_scsi_data(struct pci_dev *pdev, struct scsi_cmnd *cmd)
 {
 	dprintk(KERN_WARNING "3w-xxxx: tw_unmap_scsi_data()\n");
 
-	scsi_dma_unmap(cmd);
+	if (cmd->SCp.phase == TW_PHASE_SGLIST)
+		scsi_dma_unmap(cmd);
 } /* End tw_unmap_scsi_data() */
 
 /* This function will reset a device extension */

drivers/scsi/3w-xxxx.h

@@ -6,7 +6,7 @@
    		     Arnaldo Carvalho de Melo <acme@conectiva.com.br>
                      Brad Strand <linux@3ware.com>
 
-   Copyright (C) 1999-2007 3ware Inc.
+   Copyright (C) 1999-2009 3ware Inc.
 
    Kernel compatiblity By:	Andre Hedrick <andre@suse.com>
    Non-Copyright (C) 2000	Andre Hedrick <andre@suse.com>