[lustre-devel] [PATCH 06/37] lustre: obd_type: discard obd_types linked list.

[James Simmons <jsimmons@infradead.org>]

> As all obd_types are kobjects in the lustre_kset kset,
> they are linked together in that kset and don't
> need any extra linkage.
> 
> As kset_find_obj() returns a counted reference, we need
> to put that reference when done.
>
> Signed-off-by: NeilBrown <neilb@suse.com>
> ---
>  drivers/staging/lustre/lustre/include/obd.h     |    1 -
>  drivers/staging/lustre/lustre/obdclass/genops.c |   41 +++++++++++------------
>  2 files changed, 19 insertions(+), 23 deletions(-)
> 
> diff --git a/drivers/staging/lustre/lustre/include/obd.h b/drivers/staging/lustre/lustre/include/obd.h
> index 3aa9cc889949..50f33f400075 100644
> --- a/drivers/staging/lustre/lustre/include/obd.h
> +++ b/drivers/staging/lustre/lustre/include/obd.h
> @@ -99,7 +99,6 @@ struct obd_info {
>  };
>  
>  struct obd_type {
> -	struct list_head	 typ_chain;
>  	struct obd_ops		*typ_dt_ops;
>  	struct md_ops		*typ_md_ops;
>  	struct dentry		*typ_debugfs_entry;
> diff --git a/drivers/staging/lustre/lustre/obdclass/genops.c b/drivers/staging/lustre/lustre/obdclass/genops.c
> index 32581f1a92ac..775e4fa4f6a8 100644
> --- a/drivers/staging/lustre/lustre/obdclass/genops.c
> +++ b/drivers/staging/lustre/lustre/obdclass/genops.c
> @@ -42,8 +42,6 @@
>  #include <lprocfs_status.h>
>  #include <lustre_kernelcomm.h>
>  
> -static DEFINE_SPINLOCK(obd_types_lock);
> -static LIST_HEAD(obd_types);
>  DEFINE_RWLOCK(obd_dev_lock);
>  static struct obd_device *obd_devs[MAX_OBD_DEVICES];
>  
> @@ -88,22 +86,19 @@ static void obd_device_free(struct obd_device *obd)
>  
>  static struct obd_type *class_search_type(const char *name)
>  {
> -	struct obd_type *type;
> +	struct kobject *kobj = kset_find_obj(lustre_kset, name);
> +
> +	if (kobj)
> +		return container_of(kobj, struct obd_type, typ_kobj);
>  
> -	spin_lock(&obd_types_lock);
> -	list_for_each_entry(type, &obd_types, typ_chain) {
> -		if (strcmp(type->typ_name, name) == 0) {
> -			spin_unlock(&obd_types_lock);
> -			return type;
> -		}
> -	}
> -	spin_unlock(&obd_types_lock);
>  	return NULL;
>  }
>  
>  static struct obd_type *class_get_type(const char *name)
>  {
> -	struct obd_type *type = class_search_type(name);
> +	struct obd_type *type;
> +
> +	type = class_search_type(name);
>  
>  	if (!type) {
>  		const char *modname = name;
> @@ -121,6 +116,11 @@ static struct obd_type *class_get_type(const char *name)
>  		type->typ_refcnt++;
>  		try_module_get(type->typ_dt_ops->owner);
>  		spin_unlock(&type->obd_type_lock);
> +		/* class_search_type() returned a counted reference,
> +		 * but we don't need that count any more as
> +		 * we have one through typ_refcnt.
> +		 */
> +		kobject_put(&type->typ_kobj);
>  	}
>  	return type;
>  }
> @@ -143,10 +143,6 @@ static void class_sysfs_release(struct kobject *kobj)
>  	if (type->typ_lu)
>  		lu_device_type_fini(type->typ_lu);
>  
> -	spin_lock(&obd_types_lock);
> -	list_del(&type->typ_chain);
> -	spin_unlock(&obd_types_lock);
> -
>  	kfree(type->typ_md_ops);
>  	kfree(type->typ_dt_ops);
>  	kfree(type);
> @@ -169,8 +165,10 @@ int class_register_type(struct obd_ops *dt_ops, struct md_ops *md_ops,
>  	/* sanity check */
>  	LASSERT(strnlen(name, CLASS_MAX_NAME) < CLASS_MAX_NAME);
>  
> -	if (class_search_type(name)) {
> +	type = class_search_type(name);
> +	if (type) {
>  		CDEBUG(D_IOCTL, "Type %s already registered\n", name);
> +		kobject_put(&type->typ_kobj);
>  		return -EEXIST;
>  	}
>  
> @@ -181,7 +179,6 @@ int class_register_type(struct obd_ops *dt_ops, struct md_ops *md_ops,
>  
>  	type->typ_kobj.kset = lustre_kset;
>  	kobject_init(&type->typ_kobj, &class_ktype);
> -	INIT_LIST_HEAD(&type->typ_chain);
>  
>  	type->typ_dt_ops = kzalloc(sizeof(*type->typ_dt_ops), GFP_NOFS);
>  	type->typ_md_ops = kzalloc(sizeof(*type->typ_md_ops), GFP_NOFS);
> @@ -210,10 +207,6 @@ int class_register_type(struct obd_ops *dt_ops, struct md_ops *md_ops,
>  			goto failed;
>  	}
>  
> -	spin_lock(&obd_types_lock);
> -	list_add(&type->typ_chain, &obd_types);
> -	spin_unlock(&obd_types_lock);
> -
>  	return 0;
>  
>  failed:
> @@ -238,9 +231,13 @@ int class_unregister_type(const char *name)
>  		/* Remove ops, but leave the name for debugging */
>  		kfree(type->typ_dt_ops);
>  		kfree(type->typ_md_ops);
> +		kobject_put(&type->typ_kobj);
>  		return -EBUSY;
>  	}
>  
> +	/* Put the ref returned by class_search_type() */
> +	kobject_put(&type->typ_kobj);
> +	/* Put the final ref */
>  	kobject_put(&type->typ_kobj);

This last part needs to be kobject_del(&type->typ_kobj); but that
will be handled in the early patch.

>  	return 0;
> 
> 
>