few nits below.
> +/*
> + * Allocate a iommu_process structure for the given task.
> + *
> + * Ideally we shouldn't need the domain parameter, since iommu_process is
> + * system-wide, but we use it to retrieve the driver's allocation ops and a
> + * PASID range.
> + */
> +static struct iommu_process *
> +iommu_process_alloc(struct iommu_domain *domain, struct task_struct *task)
> +{
> + int err;
> + int pasid;
> + struct iommu_process *process;
> +
> + if (WARN_ON(!domain->ops->process_alloc || !domain->ops->process_free))
> + return ERR_PTR(-ENODEV);
> +
> + process = domain->ops->process_alloc(task);
> + if (IS_ERR(process))
> + return process;
> + if (!process)
> + return ERR_PTR(-ENOMEM);
> +
> + process->pid = get_task_pid(task, PIDTYPE_PID);
> + process->release = domain->ops->process_free;
> + INIT_LIST_HEAD(&process->domains);
> + kref_init(&process->kref);
> +
nit, I think you should place this check right after the pid assignment.
> + if (!process->pid) {
> + err = -EINVAL;
> + goto err_free_process;
> + }
> +
> + idr_preload(GFP_KERNEL);
> + spin_lock(&iommu_process_lock);
> + pasid = idr_alloc_cyclic(&iommu_process_idr, process, domain->min_pasid,
> + domain->max_pasid + 1, GFP_ATOMIC);
> + process->pasid = pasid;
> + spin_unlock(&iommu_process_lock);
> + idr_preload_end();
> +
nit, You can maybe return here if pasid is not negative.
> + if (pasid < 0) {
> + err = pasid;
> + goto err_put_pid;
> + }
> +
> + return process;
> +
> +err_put_pid:
> + put_pid(process->pid);
> +
> +err_free_process:
> + domain->ops->process_free(process);
> +
> + return ERR_PTR(err);
> +}
> +
> +static void iommu_process_release(struct kref *kref)
> +{
> + struct iommu_process *process;
> + void (*release)(struct iommu_process *);
> +
> + assert_spin_locked(&iommu_process_lock);
> +
> + process = container_of(kref, struct iommu_process, kref);
if we are concerned about things going wrong (assert above), we should
also add some pointer check here (WARN) for process and release pointers as well.
> + release = process->release;
> +
> + WARN_ON(!list_empty(&process->domains));
> +
> + idr_remove(&iommu_process_idr, process->pasid);
> + put_pid(process->pid);
> + release(process);
> +}
> +
> +/*
> + * Returns non-zero if a reference to the process was successfully taken.
> + * Returns zero if the process is being freed and should not be used.
> + */
> +static int iommu_process_get_locked(struct iommu_process *process)
> +{
> + assert_spin_locked(&iommu_process_lock);
> +
> + if (process)
> + return kref_get_unless_zero(&process->kref);
> +
> + return 0;
> +}
> +
> +static void iommu_process_put_locked(struct iommu_process *process)
> +{
> + assert_spin_locked(&iommu_process_lock);
> +
> + kref_put(&process->kref, iommu_process_release);
> +}
> +
> +static int iommu_process_attach(struct iommu_domain *domain, struct device *dev,
> + struct iommu_process *process)
> +{
> + int err;
> + int pasid = process->pasid;
> + struct iommu_context *context;
> +
> + if (WARN_ON(!domain->ops->process_attach || !domain->ops->process_detach))
> + return -ENODEV;
> +
> + if (pasid > domain->max_pasid || pasid < domain->min_pasid)
> + return -ENOSPC;
> +
> + context = kzalloc(sizeof(*context), GFP_KERNEL);
> + if (!context)
> + return -ENOMEM;
> +
devm_kzalloc maybe?
> + context->process = process;
> + context->domain = domain;
> + refcount_set(&context->ref, 1);
> +
> + spin_lock(&iommu_process_lock);
> + err = domain->ops->process_attach(domain, dev, process, true);
> + if (err) {
> + kfree(context);
> + spin_unlock(&iommu_process_lock);
> + return err;
> + }
> +
> + list_add(&context->process_head, &process->domains);
> + list_add(&context->domain_head, &domain->processes);
> + spin_unlock(&iommu_process_lock);
> +
> + return 0;
> +}
--
Sinan Kaya
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.
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