megaraid_sas : Add module parameter to disable IRQ-CPU affinity hint

Resending the patch. Addressed the review comments from Tomas Henzl.

For certain deployment, we may need to disable irq cpu affinity hint.
This module parameter provides option for use to disable irq cpu affinity hint
and allow irqbalancer to handle the rest.
Signed-off-by: Sumit Saxena <sumit.saxena@avagotech.com>
Signed-off-by: Kashyap Desai <kashyap.desai@avagotech.com>
Reviewed-by: Tomas Henzl <thenzl@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/scsi/megaraid/megaraid_sas_base.c

@@ -89,6 +89,10 @@ module_param(resetwaittime, int, S_IRUGO);
 MODULE_PARM_DESC(resetwaittime, "Wait time in seconds after I/O timeout "
 		 "before resetting adapter. Default: 180");
 
+int smp_affinity_enable = 1;
+module_param(smp_affinity_enable, int, S_IRUGO);
+MODULE_PARM_DESC(smp_affinity_enable, "SMP affinity feature enable/disbale Default: enable(1)");
+
 MODULE_LICENSE("GPL");
 MODULE_VERSION(MEGASAS_VERSION);
 MODULE_AUTHOR("megaraidlinux@lsi.com");
@@ -5162,6 +5166,7 @@ static int megasas_probe_one(struct pci_dev *pdev,
 				printk(KERN_DEBUG "megasas: Failed to "
 				       "register IRQ for vector %d.\n", i);
 				for (j = 0; j < i; j++) {
+					if (smp_affinity_enable)
 						irq_set_affinity_hint(
 							instance->msixentry[j].vector, NULL);
 					free_irq(
@@ -5172,12 +5177,15 @@ static int megasas_probe_one(struct pci_dev *pdev,
 				instance->msix_vectors = 0;
 				goto retry_irq_register;
 			}
+			if (smp_affinity_enable) {
 				if (irq_set_affinity_hint(instance->msixentry[i].vector,
 					get_cpu_mask(cpu)))
-				dev_err(&instance->pdev->dev, "Error setting"
-					"affinity hint for cpu %d\n", cpu);
+					dev_err(&instance->pdev->dev,
+						"Error setting affinity hint "
+						"for cpu %d\n", cpu);
 				cpu = cpumask_next(cpu, cpu_online_mask);
 			}
+		}
 	} else {
 		instance->irq_context[0].instance = instance;
 		instance->irq_context[0].MSIxIndex = 0;
@@ -5235,6 +5243,7 @@ static int megasas_probe_one(struct pci_dev *pdev,
 	instance->instancet->disable_intr(instance);
 	if (instance->msix_vectors)
 		for (i = 0; i < instance->msix_vectors; i++) {
+			if (smp_affinity_enable)
 				irq_set_affinity_hint(
 					instance->msixentry[i].vector, NULL);
 			free_irq(instance->msixentry[i].vector,
@@ -5399,6 +5408,7 @@ megasas_suspend(struct pci_dev *pdev, pm_message_t state)
 
 	if (instance->msix_vectors)
 		for (i = 0; i < instance->msix_vectors; i++) {
+			if (smp_affinity_enable)
 				irq_set_affinity_hint(
 					instance->msixentry[i].vector, NULL);
 			free_irq(instance->msixentry[i].vector,
@@ -5509,6 +5519,7 @@ megasas_resume(struct pci_dev *pdev)
 				printk(KERN_DEBUG "megasas: Failed to "
 				       "register IRQ for vector %d.\n", i);
 				for (j = 0; j < i; j++) {
+					if (smp_affinity_enable)
 						irq_set_affinity_hint(
 							instance->msixentry[j].vector, NULL);
 					free_irq(
@@ -5518,12 +5529,15 @@ megasas_resume(struct pci_dev *pdev)
 				goto fail_irq;
 			}
 
+			if (smp_affinity_enable) {
 				if (irq_set_affinity_hint(instance->msixentry[i].vector,
 					get_cpu_mask(cpu)))
-				dev_err(&instance->pdev->dev, "Error setting"
-					"affinity hint for cpu %d\n", cpu);
+					dev_err(&instance->pdev->dev, "Error "
+						"setting affinity hint for cpu "
+						"%d\n", cpu);
 				cpu = cpumask_next(cpu, cpu_online_mask);
 			}
+		}
 	} else {
 		instance->irq_context[0].instance = instance;
 		instance->irq_context[0].MSIxIndex = 0;
@@ -5640,6 +5654,7 @@ static void megasas_detach_one(struct pci_dev *pdev)
 
 	if (instance->msix_vectors)
 		for (i = 0; i < instance->msix_vectors; i++) {
+			if (smp_affinity_enable)
 				irq_set_affinity_hint(
 					instance->msixentry[i].vector, NULL);
 			free_irq(instance->msixentry[i].vector,
@@ -5729,6 +5744,7 @@ static void megasas_shutdown(struct pci_dev *pdev)
 	instance->instancet->disable_intr(instance);
 	if (instance->msix_vectors)
 		for (i = 0; i < instance->msix_vectors; i++) {
+			if (smp_affinity_enable)
 				irq_set_affinity_hint(
 					instance->msixentry[i].vector, NULL);
 			free_irq(instance->msixentry[i].vector,