[PATCH RFC 56/77] nvme: Update MSI/MSI-X interrupts enablement code

[Alexander Gordeev]

As result of recent re-design of the MSI/MSI-X interrupts enabling
pattern this driver has to be updated to use the new technique to
obtain a optimal number of MSI/MSI-X interrupts required.

Signed-off-by: Alexander Gordeev <agordeev at redhat.com>
---
 drivers/block/nvme-core.c |   48 +++++++++++++++++++++++---------------------
 1 files changed, 25 insertions(+), 23 deletions(-)

diff --git a/drivers/block/nvme-core.c b/drivers/block/nvme-core.c
index da52092..f69d7af 100644
--- a/drivers/block/nvme-core.c
+++ b/drivers/block/nvme-core.c
@@ -1774,34 +1774,36 @@ static int nvme_setup_io_queues(struct nvme_dev *dev)
 	/* Deregister the admin queue's interrupt */
 	free_irq(dev->entry[0].vector, dev->queues[0]);
 
-	vecs = nr_io_queues;
+	result = pci_msix_table_size(pdev);
+	if (result < 0)
+		goto msi;
+
+	vecs = min(result, nr_io_queues);
 	for (i = 0; i < vecs; i++)
 		dev->entry[i].entry = i;
-	for (;;) {
-		result = pci_enable_msix(pdev, dev->entry, vecs);
-		if (result <= 0)
-			break;
-		vecs = result;
-	}
 
-	if (result < 0) {
-		vecs = nr_io_queues;
-		if (vecs > 32)
-			vecs = 32;
-		for (;;) {
-			result = pci_enable_msi_block(pdev, vecs);
-			if (result == 0) {
-				for (i = 0; i < vecs; i++)
-					dev->entry[i].vector = i + pdev->irq;
-				break;
-			} else if (result < 0) {
-				vecs = 1;
-				break;
-			}
-			vecs = result;
-		}
+	result = pci_enable_msix(pdev, dev->entry, vecs);
+	if (result == 0)
+		goto irq;
+
+ msi:
+	result = pci_get_msi_cap(pdev);
+	if (result < 0)
+		goto no_msi;
+
+	vecs = min(result, nr_io_queues);
+
+	result = pci_enable_msi_block(pdev, vecs);
+	if (result == 0) {
+		for (i = 0; i < vecs; i++)
+			dev->entry[i].vector = i + pdev->irq;
+		goto irq;
 	}
 
+ no_msi:
+	vecs = 1;
+
+ irq:
 	/*
 	 * Should investigate if there's a performance win from allocating
 	 * more queues than interrupt vectors; it might allow the submission
-- 
1.7.7.6