--- linux/drivers/scsi/libata-core.c.ori	2005-06-30 17:16:28.000000000 +0800
+++ linux/drivers/scsi/libata-core.c	2005-06-30 17:35:50.000000000 +0800
@@ -3086,9 +3086,14 @@
 	if (likely(qc->flags & ATA_QCFLAG_DMAMAP))
 		ata_sg_clean(qc);
 
+	/* atapi: inactivate qc to prevent the interrupt handler from 
+	 * completing the command twice, before the scsi error handler
+	 * is called.
+	 */
+	qc->flags &= ~ATA_QCFLAG_ACTIVE;
+
 	/* call completion callback */
 	rc = qc->complete_fn(qc, drv_stat);
-	qc->flags &= ~ATA_QCFLAG_ACTIVE;
 
 	/* if callback indicates not to complete command (non-zero),
 	 * return immediately