[PATCH] drm/amdkfd: Add procfs-style information for KFD processes

[Christian König]

Am 19.06.19 um 16:01 schrieb Russell, Kent:
> Add a folder structure to /sys/class/kfd/kfd/ called proc which contains
> subfolders, each representing an active KFD process' PID, containing 1
> file: pasid.

What is the use case of that information? In other words would it be 
maybe better to create debugfs entries instead?

Christian.

>
> Change-Id: Id3dfab8a6250264434b34ccddbcdb459d1da7478
> Signed-off-by: Kent Russell <kent.russell at amd.com>
> ---
>   drivers/gpu/drm/amd/amdkfd/kfd_module.c  |   6 ++
>   drivers/gpu/drm/amd/amdkfd/kfd_priv.h    |   9 ++
>   drivers/gpu/drm/amd/amdkfd/kfd_process.c | 100 ++++++++++++++++++++++-
>   3 files changed, 113 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_module.c b/drivers/gpu/drm/amd/amdkfd/kfd_module.c
> index 932007eb9168..986ff52d5750 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_module.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_module.c
> @@ -56,6 +56,11 @@ static int kfd_init(void)
>   	if (err < 0)
>   		goto err_create_wq;
>   
> +	/* Ignore the return value, so that we can continue
> +	 * to init the KFD, even if procfs isn't craated
> +	 */
> +	kfd_procfs_init();
> +
>   	kfd_debugfs_init();
>   
>   	return 0;
> @@ -72,6 +77,7 @@ static void kfd_exit(void)
>   {
>   	kfd_debugfs_fini();
>   	kfd_process_destroy_wq();
> +	kfd_procfs_shutdown();
>   	kfd_topology_shutdown();
>   	kfd_chardev_exit();
>   }
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
> index da589ee1366c..bd01396c8cea 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
> @@ -35,6 +35,7 @@
>   #include <linux/kfifo.h>
>   #include <linux/seq_file.h>
>   #include <linux/kref.h>
> +#include <linux/sysfs.h>
>   #include <kgd_kfd_interface.h>
>   
>   #include "amd_shared.h"
> @@ -718,6 +719,10 @@ struct kfd_process {
>   	 * restored after an eviction
>   	 */
>   	unsigned long last_restore_timestamp;
> +
> +	/* Kobj for our procfs */
> +	struct kobject *kobj;
> +	struct attribute attr_pasid;
>   };
>   
>   #define KFD_PROCESS_TABLE_SIZE 5 /* bits: 32 entries */
> @@ -820,6 +825,10 @@ int kfd_gtt_sa_free(struct kfd_dev *kfd, struct kfd_mem_obj *mem_obj);
>   
>   extern struct device *kfd_device;
>   
> +/* KFD's procfs */
> +void kfd_procfs_init(void);
> +void kfd_procfs_shutdown(void);
> +
>   /* Topology */
>   int kfd_topology_init(void);
>   void kfd_topology_shutdown(void);
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> index 4bdae78bab8e..ed2d83f93fd8 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> @@ -68,6 +68,68 @@ static struct kfd_process *create_process(const struct task_struct *thread,
>   static void evict_process_worker(struct work_struct *work);
>   static void restore_process_worker(struct work_struct *work);
>   
> +struct kfd_procfs_tree {
> +	struct kobject *kobj;
> +};
> +
> +static struct kfd_procfs_tree procfs;
> +
> +static ssize_t kfd_procfs_show(struct kobject *kobj, struct attribute *attr,
> +			       char *buffer)
> +{
> +	int val = 0;
> +
> +	if (strcmp(attr->name, "pasid") == 0) {
> +		struct kfd_process *p = container_of(attr, struct kfd_process,
> +						     attr_pasid);
> +		val = p->pasid;
> +	} else {
> +		pr_err("Invalid attribute");
> +		return -EINVAL;
> +	}
> +
> +	return snprintf(buffer, PAGE_SIZE, "%d\n", val);
> +}
> +
> +static void kfd_procfs_kobj_release(struct kobject *kobj)
> +{
> +	kfree(kobj);
> +}
> +
> +static const struct sysfs_ops kfd_procfs_ops = {
> +	.show = kfd_procfs_show,
> +};
> +
> +static struct kobj_type procfs_type = {
> +	.release = kfd_procfs_kobj_release,
> +	.sysfs_ops = &kfd_procfs_ops,
> +};
> +
> +void kfd_procfs_init(void)
> +{
> +	int ret = 0;
> +
> +	procfs.kobj = kfd_alloc_struct(procfs.kobj);
> +	if (!procfs.kobj)
> +		return;
> +
> +	ret = kobject_init_and_add(procfs.kobj, &procfs_type,
> +				   &kfd_device->kobj, "proc");
> +	if (ret) {
> +		pr_warn("Could not create procfs proc folder");
> +		/* If we fail to create the procfs, clean up */
> +		kfd_procfs_shutdown();
> +	}
> +}
> +
> +void kfd_procfs_shutdown(void)
> +{
> +	if (procfs.kobj) {
> +		kobject_del(procfs.kobj);
> +		kobject_put(procfs.kobj);
> +		procfs.kobj = NULL;
> +	}
> +}
>   
>   int kfd_process_create_wq(void)
>   {
> @@ -206,6 +268,7 @@ struct kfd_process *kfd_create_process(struct file *filep)
>   {
>   	struct kfd_process *process;
>   	struct task_struct *thread = current;
> +	int ret;
>   
>   	if (!thread->mm)
>   		return ERR_PTR(-EINVAL);
> @@ -223,11 +286,36 @@ struct kfd_process *kfd_create_process(struct file *filep)
>   
>   	/* A prior open of /dev/kfd could have already created the process. */
>   	process = find_process(thread);
> -	if (process)
> +	if (process) {
>   		pr_debug("Process already found\n");
> -	else
> +	} else {
>   		process = create_process(thread, filep);
>   
> +		if (!procfs.kobj)
> +			goto out;
> +
> +		process->kobj = kfd_alloc_struct(process->kobj);
> +		if (!process->kobj) {
> +			pr_warn("Creating procfs kobject failed");
> +			goto out;
> +		}
> +		ret = kobject_init_and_add(process->kobj, &procfs_type,
> +					   procfs.kobj, "%d",
> +					   (int)process->lead_thread->pid);
> +		if (ret) {
> +			pr_warn("Creating procfs pid directory failed");
> +			goto out;
> +		}
> +
> +		process->attr_pasid.name = "pasid";
> +		process->attr_pasid.mode = KFD_SYSFS_FILE_MODE;
> +		sysfs_attr_init(&process->attr_pasid);
> +		ret = sysfs_create_file(process->kobj, &process->attr_pasid);
> +		if (ret)
> +			pr_warn("Creating pasid for pid %d failed",
> +					(int)process->lead_thread->pid);
> +	}
> +out:
>   	mutex_unlock(&kfd_processes_mutex);
>   
>   	return process;
> @@ -355,6 +443,14 @@ static void kfd_process_wq_release(struct work_struct *work)
>   	struct kfd_process *p = container_of(work, struct kfd_process,
>   					     release_work);
>   
> +	/* Remove the procfs files */
> +	if (p->kobj) {
> +		sysfs_remove_file(p->kobj, &p->attr_pasid);
> +		kobject_del(p->kobj);
> +		kobject_put(p->kobj);
> +		p->kobj = NULL;
> +	}
> +
>   	kfd_iommu_unbind_process(p);
>   
>   	kfd_process_free_outstanding_kfd_bos(p);