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SubjectRe: [PATCH 2/5] iommu/omap: Permanently keep iommu_dev pointer in arch_data
Date
Hi Joerg,

On 03/31/2017 07:10 AM, Joerg Roedel wrote:
> From: Joerg Roedel <jroedel@suse.de>
>
> Instead of finding the matching IOMMU for a device using
> string comparision functions, keep the pointer to the
> iommu_dev in arch_data permanently populated.
>
> Signed-off-by: Joerg Roedel <jroedel@suse.de>
> ---
> drivers/iommu/omap-iommu.c | 56 ++++++++++++++++++++--------------------------
> drivers/iommu/omap-iommu.h | 2 +-
> 2 files changed, 25 insertions(+), 33 deletions(-)
>
> diff --git a/drivers/iommu/omap-iommu.c b/drivers/iommu/omap-iommu.c
> index e9c9b08..45df5c8 100644
> --- a/drivers/iommu/omap-iommu.c
> +++ b/drivers/iommu/omap-iommu.c
> @@ -802,33 +802,14 @@ static irqreturn_t iommu_fault_handler(int irq, void *data)
> return IRQ_NONE;
> }
>
> -static int device_match_by_alias(struct device *dev, void *data)
> -{
> - struct omap_iommu *obj = to_iommu(dev);
> - const char *name = data;
> -
> - pr_debug("%s: %s %s\n", __func__, obj->name, name);
> -
> - return strcmp(obj->name, name) == 0;
> -}
> -
> /**
> * omap_iommu_attach() - attach iommu device to an iommu domain
> - * @name: name of target omap iommu device
> + * @obj: target omap iommu device
> * @iopgd: page table
> **/
> -static struct omap_iommu *omap_iommu_attach(const char *name, u32 *iopgd)
> +static int omap_iommu_attach(struct omap_iommu *obj, u32 *iopgd)
> {
> int err;
> - struct device *dev;
> - struct omap_iommu *obj;
> -
> - dev = driver_find_device(&omap_iommu_driver.driver, NULL, (void *)name,
> - device_match_by_alias);
> - if (!dev)
> - return ERR_PTR(-ENODEV);
> -
> - obj = to_iommu(dev);
>
> spin_lock(&obj->iommu_lock);
>
> @@ -841,11 +822,13 @@ static struct omap_iommu *omap_iommu_attach(const char *name, u32 *iopgd)
> spin_unlock(&obj->iommu_lock);
>
> dev_dbg(obj->dev, "%s: %s\n", __func__, obj->name);
> - return obj;
> +
> + return 0;
>
> err_enable:
> spin_unlock(&obj->iommu_lock);
> - return ERR_PTR(err);
> +
> + return err;
> }
>
> /**
> @@ -1061,11 +1044,11 @@ static size_t omap_iommu_unmap(struct iommu_domain *domain, unsigned long da,
> omap_iommu_attach_dev(struct iommu_domain *domain, struct device *dev)
> {
> struct omap_iommu_domain *omap_domain = to_omap_domain(domain);
> - struct omap_iommu *oiommu;
> struct omap_iommu_arch_data *arch_data = dev->archdata.iommu;
> + struct omap_iommu *oiommu;
> int ret = 0;
>
> - if (!arch_data || !arch_data->name) {
> + if (!arch_data || !arch_data->iommu_dev) {
> dev_err(dev, "device doesn't have an associated iommu\n");
> return -EINVAL;
> }
> @@ -1079,15 +1062,17 @@ static size_t omap_iommu_unmap(struct iommu_domain *domain, unsigned long da,
> goto out;
> }
>
> + oiommu = arch_data->iommu_dev;
> +
> /* get a handle to and enable the omap iommu */
> - oiommu = omap_iommu_attach(arch_data->name, omap_domain->pgtable);
> - if (IS_ERR(oiommu)) {
> - ret = PTR_ERR(oiommu);
> + ret = omap_iommu_attach(oiommu, omap_domain->pgtable);
> + if (ret) {
> dev_err(dev, "can't get omap iommu: %d\n", ret);
> goto out;
> }
>
> - omap_domain->iommu_dev = arch_data->iommu_dev = oiommu;
> + arch_data->domain = omap_domain;
> + omap_domain->iommu_dev = oiommu;
> omap_domain->dev = dev;
> oiommu->domain = domain;
>
> @@ -1112,7 +1097,8 @@ static void _omap_iommu_detach_dev(struct omap_iommu_domain *omap_domain,
>
> omap_iommu_detach(oiommu);
>
> - omap_domain->iommu_dev = arch_data->iommu_dev = NULL;
> + omap_domain->iommu_dev = NULL;
> + arch_data->domain = NULL;
> omap_domain->dev = NULL;
> oiommu->domain = NULL;
> }
> @@ -1216,6 +1202,7 @@ static phys_addr_t omap_iommu_iova_to_phys(struct iommu_domain *domain,
> static int omap_iommu_add_device(struct device *dev)
> {
> struct omap_iommu_arch_data *arch_data;
> + struct omap_iommu *iommu;
> struct device_node *np;
> struct platform_device *pdev;
>
> @@ -1238,13 +1225,19 @@ static int omap_iommu_add_device(struct device *dev)
> return -EINVAL;
> }
>
> + iommu = platform_get_drvdata(pdev);
> + if (!iommu) {
> + of_node_put(np);
> + return -EINVAL;
> + }

This change is causing the issues. OMAP IOMMU driver is not probed yet,
but this gets called during the driver's init function in
bus_set_iommu() and bus's iommu_ops gets set to NULL. The add_device
today is used to add the linking to an IOMMU device (currently name
primarily to support the legacy non-DT mode which is no longer an issue,
but a dev pointer can be used instead here, and the real enabling is
done during the domain's attach_dev callback.

> +
> arch_data = kzalloc(sizeof(*arch_data), GFP_KERNEL);
> if (!arch_data) {
> of_node_put(np);
> return -ENOMEM;
> }
>
> - arch_data->name = kstrdup(dev_name(&pdev->dev), GFP_KERNEL);
> + arch_data->iommu_dev = iommu;
> dev->archdata.iommu = arch_data;
>
> of_node_put(np);
> @@ -1259,7 +1252,6 @@ static void omap_iommu_remove_device(struct device *dev)
> if (!dev->of_node || !arch_data)
> return;
>
> - kfree(arch_data->name);
> kfree(arch_data);
> }
>
> diff --git a/drivers/iommu/omap-iommu.h b/drivers/iommu/omap-iommu.h
> index 3cd414a..05bd279 100644
> --- a/drivers/iommu/omap-iommu.h
> +++ b/drivers/iommu/omap-iommu.h
> @@ -80,8 +80,8 @@ struct omap_iommu {
> * utilize omap-specific plumbing anymore.
> */
> struct omap_iommu_arch_data {
> - const char *name;

Missing the removal from the structure kerneldoc documentation.

> struct omap_iommu *iommu_dev;
> + struct omap_iommu_domain *domain;

This doesn't seem to serve any purpose for now, is there a plan/purpose
for this? The iommu_domain is being stored within the omap_iommu
structure at the moment and it is stored during attach_dev() callback.

regards
Suman

> };
>
> struct cr_regs {
>

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