Panic on boot with today's CURRENT, ata related

[Søren Schmidt]

Nate Lawson wrote:
> I took a quick look at this ATA panic.  The exact same one occurs for 
> Ceri.  A quick dissassemble shows that the testb is the check for the 
> DMA flag at the very end of ata_generic_transaction().  The bug appears 
> to be that this may be a PIO request (since the DMA check is outside the 
> switch() statement).  The fix is to make sure it's a DMA request before 
> dereferencing an element of the DMA struct.  Try the attached patch.

No, the fix is to make sure there is a valid ch->dma pointer, the below 
is the correct fix.

--- ata-lowlevel.c      5 Aug 2004 21:13:41 -0000       1.41
+++ ata-lowlevel.c      6 Aug 2004 22:31:16 -0000
@@ -295,7 +295,7 @@
      }

      /* request finish here */
-    if (ch->dma->flags & ATA_DMA_LOADED)
+    if (ch->dma && ch->dma->flags & ATA_DMA_LOADED)
         ch->dma->unload(ch);
      return ATA_OP_FINISHED;
  }