Re: [PATCH 07/10] acpi: Do not return struct iommu_ops from acpi_iommu_configure_id()

[Moritz Fischer]

On Tue, Nov 28, 2023 at 08:48:03PM -0400, Jason Gunthorpe wrote:

Nothing needs this pointer. Return a normal error code with the usual
IOMMU semantic that ENODEV means 'there is no IOMMU driver'.

Acked-by: Rafael J. Wysocki <rafael.j.wyso...@intel.com>
Reviewed-by: Jerry Snitselaar <jsnit...@redhat.com>
Tested-by: Hector Martin <mar...@marcan.st>
Signed-off-by: Jason Gunthorpe <j...@nvidia.com>
---
  drivers/acpi/scan.c | 29 +++++++++++++++++------------
  1 file changed, 17 insertions(+), 12 deletions(-)

diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 444a0b3c72f2d8..340ba720c72129 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c

@@ -1562,8 +1562,7 @@ static inline const struct iommu_ops *acpi_iommu_fwspec_ops(struct device *dev)

        return fwspec ? fwspec->ops : NULL;
  }

-static const struct iommu_ops *acpi_iommu_configure_id(struct device *dev,

-                                                      const u32 *id_in)
+static int acpi_iommu_configure_id(struct device *dev, const u32 *id_in)
  {
        int err;
        const struct iommu_ops *ops;

@@ -1577,7 +1576,7 @@ static const struct iommu_ops *acpi_iommu_configure_id(struct device *dev,

        ops = acpi_iommu_fwspec_ops(dev);
        if (ops) {
                mutex_unlock(&iommu_probe_device_lock);
-               return ops;
+               return 0;
        }

        err = iort_iommu_configure_id(dev, id_in);

@@ -1594,12 +1593,14 @@ static const struct iommu_ops *acpi_iommu_configure_id(struct device *dev,

        /* Ignore all other errors apart from EPROBE_DEFER */
        if (err == -EPROBE_DEFER) {
-               return ERR_PTR(err);
+               return err;
        } else if (err) {
                dev_dbg(dev, "Adding to IOMMU failed: %d\n", err);
-               return NULL;
+               return -ENODEV;
        }
-       return acpi_iommu_fwspec_ops(dev);
+       if (!acpi_iommu_fwspec_ops(dev))
+               return -ENODEV;
+       return 0;
  }

  #else /* !CONFIG_IOMMU_API */

@@ -1611,10 +1612,9 @@ int acpi_iommu_fwspec_init(struct device *dev, u32 id,

        return -ENODEV;
  }

-static const struct iommu_ops *acpi_iommu_configure_id(struct device *dev,

-                                                      const u32 *id_in)
+static int acpi_iommu_configure_id(struct device *dev, const u32 *id_in)
  {
-       return NULL;
+       return -ENODEV;
  }

  #endif /* !CONFIG_IOMMU_API */

@@ -1628,7 +1628,7 @@ static const struct iommu_ops *acpi_iommu_configure_id(struct device *dev,

  int acpi_dma_configure_id(struct device *dev, enum dev_dma_attr attr,
                          const u32 *input_id)
  {
-       const struct iommu_ops *iommu;
+       int ret;

        if (attr == DEV_DMA_NOT_SUPPORTED) {
                set_dma_ops(dev, &dma_dummy_ops);

@@ -1637,10 +1637,15 @@ int acpi_dma_configure_id(struct device *dev, enum dev_dma_attr attr,

        acpi_arch_dma_setup(dev);

-       iommu = acpi_iommu_configure_id(dev, input_id);
-       if (PTR_ERR(iommu) == -EPROBE_DEFER)
+       ret = acpi_iommu_configure_id(dev, input_id);
+       if (ret == -EPROBE_DEFER)
                return -EPROBE_DEFER;

+       /*
+        * Historically this routine doesn't fail driver probing due to errors
+        * in acpi_iommu_configure_id()
+        */
+
        arch_setup_dma_ops(dev, 0, U64_MAX, attr == DEV_DMA_COHERENT);

        return 0;
--
2.42.0

Reviewed-by: Moritz Fischer <mori...@google.com>

Cheers,
Moritz

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