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>

diff --git a/drivers/block/nvme-core.c b/drivers/block/nvme-core.c
index 8493708..a57d3bc 100644 (file)
--- 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;