[PATCH] libata: kill NULL qc handling from ->eng_timeout callbacks

->eng_timeout cannot be invoked with NULL qc anymore.  Add an
assertion in ata_scsi_error() and kill NULL qc handling from all
->eng_timeout callbacks.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
diff --git a/drivers/scsi/ahci.c b/drivers/scsi/ahci.c
index c67189a4..fa01894 100644
--- a/drivers/scsi/ahci.c
+++ b/drivers/scsi/ahci.c
@@ -677,19 +677,13 @@
 
 	spin_lock_irqsave(&host_set->lock, flags);
 
+	ahci_restart_port(ap, readl(port_mmio + PORT_IRQ_STAT));
 	qc = ata_qc_from_tag(ap, ap->active_tag);
-	if (!qc) {
-		printk(KERN_ERR "ata%u: BUG: timeout without command\n",
-		       ap->id);
-	} else {
-		ahci_restart_port(ap, readl(port_mmio + PORT_IRQ_STAT));
-		qc->err_mask |= AC_ERR_TIMEOUT;
-	}
+	qc->err_mask |= AC_ERR_TIMEOUT;
 
 	spin_unlock_irqrestore(&host_set->lock, flags);
 
-	if (qc)
-		ata_eh_qc_complete(qc);
+	ata_eh_qc_complete(qc);
 }
 
 static inline int ahci_host_intr(struct ata_port *ap, struct ata_queued_cmd *qc)