ahci: Do not receive interrupts sent by dummy ports

Alexander Gordeev · htejun · commit 2cf532f5e67c · 2014-04-18T15:55:57.000-04:00
In multiple MSI mode all AHCI ports (including dummy) get assigned separate MSI vectors and (as result of execution pci_enable_msi_exact() function) separate IRQ numbers, (mapped to the MSI vectors). Therefore, although interrupts from dummy ports are not desired they are still enabled. We do not request IRQs for dummy ports, but that only means we do not assign AHCI-specific ISRs to corresponding IRQ numbers. As result, dummy port interrupts still could come and traverse all the way from the PCI device to the kernel, causing unnecessary overhead. This update disables IRQs for dummy ports and prevents the described issue. Signed-off-by: Alexander Gordeev <agordeev@redhat.com> Signed-off-by: Tejun Heo <tj@kernel.org> Tested-by: David Milburn <dmilburn@redhat.com> Cc: linux-ide@vger.kernel.org Cc: stable@vger.kernel.org Fixes: 5ca72c4 ("AHCI: Support multiple MSIs")
diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
@@ -1241,12 +1241,16 @@ int ahci_host_activate(struct ata_host *host, int irq, unsigned int n_msis)
 	for (i = 0; i < host->n_ports; i++) {
 		struct ahci_port_priv *pp = host->ports[i]->private_data;
 
-		/* pp is NULL for dummy ports */
-		if (pp)
-			rc = devm_request_threaded_irq(host->dev,
-						       irq + i, ahci_hw_interrupt,
-						       ahci_thread_fn, IRQF_SHARED,
-						       pp->irq_desc, host->ports[i]);
+		/* Do not receive interrupts sent by dummy ports */
+		if (!pp) {
+			disable_irq(irq + i);
+			continue;
+		}
+
+		rc = devm_request_threaded_irq(host->dev, irq + i,
+					       ahci_hw_interrupt,
+					       ahci_thread_fn, IRQF_SHARED,
+					       pp->irq_desc, host->ports[i]);
 		if (rc)
 			goto out_free_irqs;
 	}
