NVMe: Use dma_set_mask() correctly

In some circumstances setting a 64-bit DMA mask can fail, as explained
in Documentation/DMA-API-HOWTO.txt.  Use the recommended code sequence
to set a 32-bit DMA mask if setting a 64-bit DMA mask fails.

Reported-by: Chayan Biswas <Chayan.Biswas@sandisk.com>
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>

1 files changed, 8 insertions, 2 deletions

diff --git a/drivers/block/nvme-core.c b/drivers/block/nvme-core.c
index 84937089d5db..a57d3bcec803 100644
--- a/drivers/block/nvme-core.c
+++ b/drivers/block/nvme-core.c
@@ -1927,8 +1927,14 @@ static int nvme_probe(struct pci_dev *pdev, const struct pci_device_id *id)
         INIT_LIST_HEAD(&dev->namespaces);
         dev->pci_dev = pdev;
         pci_set_drvdata(pdev, dev);
-        dma_set_mask(&pdev->dev, DMA_BIT_MASK(64));
-        dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(64));
+
+        if (!dma_set_mask(&pdev->dev, DMA_BIT_MASK(64)))
+                dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(64));
+        else if (!dma_set_mask(&pdev->dev, DMA_BIT_MASK(32)))
+                dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32));
+        else
+                goto disable;
+
         result = nvme_set_instance(dev);
         if (result)
                 goto disable;