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linux-next/lib/objagg.c
Jiri Pirko 0a020d416d lib: introduce initial implementation of object aggregation manager
This lib tracks objects which could be of two types:
1) root object
2) nested object - with a "delta" which differentiates it from
                   the associated root object
The objects are tracked by a hashtable and reference-counted. User is
responsible of implementing callbacks to create/destroy root entity
related to each root object and callback to create/destroy nested object
delta.

Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-11-15 14:43:43 -08:00

502 lines
14 KiB
C

// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
/* Copyright (c) 2018 Mellanox Technologies. All rights reserved */
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/rhashtable.h>
#include <linux/list.h>
#include <linux/sort.h>
#include <linux/objagg.h>
#define CREATE_TRACE_POINTS
#include <trace/events/objagg.h>
struct objagg {
const struct objagg_ops *ops;
void *priv;
struct rhashtable obj_ht;
struct rhashtable_params ht_params;
struct list_head obj_list;
unsigned int obj_count;
};
struct objagg_obj {
struct rhash_head ht_node; /* member of objagg->obj_ht */
struct list_head list; /* member of objagg->obj_list */
struct objagg_obj *parent; /* if the object is nested, this
* holds pointer to parent, otherwise NULL
*/
union {
void *delta_priv; /* user delta private */
void *root_priv; /* user root private */
};
unsigned int refcount; /* counts number of users of this object
* including nested objects
*/
struct objagg_obj_stats stats;
unsigned long obj[0];
};
static unsigned int objagg_obj_ref_inc(struct objagg_obj *objagg_obj)
{
return ++objagg_obj->refcount;
}
static unsigned int objagg_obj_ref_dec(struct objagg_obj *objagg_obj)
{
return --objagg_obj->refcount;
}
static void objagg_obj_stats_inc(struct objagg_obj *objagg_obj)
{
objagg_obj->stats.user_count++;
objagg_obj->stats.delta_user_count++;
if (objagg_obj->parent)
objagg_obj->parent->stats.delta_user_count++;
}
static void objagg_obj_stats_dec(struct objagg_obj *objagg_obj)
{
objagg_obj->stats.user_count--;
objagg_obj->stats.delta_user_count--;
if (objagg_obj->parent)
objagg_obj->parent->stats.delta_user_count--;
}
static bool objagg_obj_is_root(const struct objagg_obj *objagg_obj)
{
/* Nesting is not supported, so we can use ->parent
* to figure out if the object is root.
*/
return !objagg_obj->parent;
}
/**
* objagg_obj_root_priv - obtains root private for an object
* @objagg_obj: objagg object instance
*
* Note: all locking must be provided by the caller.
*
* Either the object is root itself when the private is returned
* directly, or the parent is root and its private is returned
* instead.
*
* Returns a user private root pointer.
*/
const void *objagg_obj_root_priv(const struct objagg_obj *objagg_obj)
{
if (objagg_obj_is_root(objagg_obj))
return objagg_obj->root_priv;
WARN_ON(!objagg_obj_is_root(objagg_obj->parent));
return objagg_obj->parent->root_priv;
}
EXPORT_SYMBOL(objagg_obj_root_priv);
/**
* objagg_obj_delta_priv - obtains delta private for an object
* @objagg_obj: objagg object instance
*
* Note: all locking must be provided by the caller.
*
* Returns user private delta pointer or NULL in case the passed
* object is root.
*/
const void *objagg_obj_delta_priv(const struct objagg_obj *objagg_obj)
{
if (objagg_obj_is_root(objagg_obj))
return NULL;
return objagg_obj->delta_priv;
}
EXPORT_SYMBOL(objagg_obj_delta_priv);
/**
* objagg_obj_raw - obtains object user private pointer
* @objagg_obj: objagg object instance
*
* Note: all locking must be provided by the caller.
*
* Returns user private pointer as was passed to objagg_obj_get() by "obj" arg.
*/
const void *objagg_obj_raw(const struct objagg_obj *objagg_obj)
{
return objagg_obj->obj;
}
EXPORT_SYMBOL(objagg_obj_raw);
static struct objagg_obj *objagg_obj_lookup(struct objagg *objagg, void *obj)
{
return rhashtable_lookup_fast(&objagg->obj_ht, obj, objagg->ht_params);
}
static int objagg_obj_parent_assign(struct objagg *objagg,
struct objagg_obj *objagg_obj,
struct objagg_obj *parent)
{
void *delta_priv;
delta_priv = objagg->ops->delta_create(objagg->priv, parent->obj,
objagg_obj->obj);
if (IS_ERR(delta_priv))
return PTR_ERR(delta_priv);
/* User returned a delta private, that means that
* our object can be aggregated into the parent.
*/
objagg_obj->parent = parent;
objagg_obj->delta_priv = delta_priv;
objagg_obj_ref_inc(objagg_obj->parent);
trace_objagg_obj_parent_assign(objagg, objagg_obj,
parent,
parent->refcount);
return 0;
}
static int objagg_obj_parent_lookup_assign(struct objagg *objagg,
struct objagg_obj *objagg_obj)
{
struct objagg_obj *objagg_obj_cur;
int err;
list_for_each_entry(objagg_obj_cur, &objagg->obj_list, list) {
/* Nesting is not supported. In case the object
* is not root, it cannot be assigned as parent.
*/
if (!objagg_obj_is_root(objagg_obj_cur))
continue;
err = objagg_obj_parent_assign(objagg, objagg_obj,
objagg_obj_cur);
if (!err)
return 0;
}
return -ENOENT;
}
static void __objagg_obj_put(struct objagg *objagg,
struct objagg_obj *objagg_obj);
static void objagg_obj_parent_unassign(struct objagg *objagg,
struct objagg_obj *objagg_obj)
{
trace_objagg_obj_parent_unassign(objagg, objagg_obj,
objagg_obj->parent,
objagg_obj->parent->refcount);
objagg->ops->delta_destroy(objagg->priv, objagg_obj->delta_priv);
__objagg_obj_put(objagg, objagg_obj->parent);
}
static int objagg_obj_root_create(struct objagg *objagg,
struct objagg_obj *objagg_obj)
{
objagg_obj->root_priv = objagg->ops->root_create(objagg->priv,
objagg_obj->obj);
if (IS_ERR(objagg_obj->root_priv))
return PTR_ERR(objagg_obj->root_priv);
trace_objagg_obj_root_create(objagg, objagg_obj);
return 0;
}
static void objagg_obj_root_destroy(struct objagg *objagg,
struct objagg_obj *objagg_obj)
{
trace_objagg_obj_root_destroy(objagg, objagg_obj);
objagg->ops->root_destroy(objagg->priv, objagg_obj->root_priv);
}
static int objagg_obj_init(struct objagg *objagg,
struct objagg_obj *objagg_obj)
{
int err;
/* Try to find if the object can be aggregated under an existing one. */
err = objagg_obj_parent_lookup_assign(objagg, objagg_obj);
if (!err)
return 0;
/* If aggregation is not possible, make the object a root. */
return objagg_obj_root_create(objagg, objagg_obj);
}
static void objagg_obj_fini(struct objagg *objagg,
struct objagg_obj *objagg_obj)
{
if (!objagg_obj_is_root(objagg_obj))
objagg_obj_parent_unassign(objagg, objagg_obj);
else
objagg_obj_root_destroy(objagg, objagg_obj);
}
static struct objagg_obj *objagg_obj_create(struct objagg *objagg, void *obj)
{
struct objagg_obj *objagg_obj;
int err;
objagg_obj = kzalloc(sizeof(*objagg_obj) + objagg->ops->obj_size,
GFP_KERNEL);
if (!objagg_obj)
return ERR_PTR(-ENOMEM);
objagg_obj_ref_inc(objagg_obj);
memcpy(objagg_obj->obj, obj, objagg->ops->obj_size);
err = objagg_obj_init(objagg, objagg_obj);
if (err)
goto err_obj_init;
err = rhashtable_insert_fast(&objagg->obj_ht, &objagg_obj->ht_node,
objagg->ht_params);
if (err)
goto err_ht_insert;
list_add(&objagg_obj->list, &objagg->obj_list);
objagg->obj_count++;
trace_objagg_obj_create(objagg, objagg_obj);
return objagg_obj;
err_ht_insert:
objagg_obj_fini(objagg, objagg_obj);
err_obj_init:
kfree(objagg_obj);
return ERR_PTR(err);
}
static struct objagg_obj *__objagg_obj_get(struct objagg *objagg, void *obj)
{
struct objagg_obj *objagg_obj;
/* First, try to find the object exactly as user passed it,
* perhaps it is already in use.
*/
objagg_obj = objagg_obj_lookup(objagg, obj);
if (objagg_obj) {
objagg_obj_ref_inc(objagg_obj);
return objagg_obj;
}
return objagg_obj_create(objagg, obj);
}
/**
* objagg_obj_get - gets an object within objagg instance
* @objagg: objagg instance
* @obj: user-specific private object pointer
*
* Note: all locking must be provided by the caller.
*
* Size of the "obj" memory is specified in "objagg->ops".
*
* There are 3 main options this function wraps:
* 1) The object according to "obj" already exist. In that case
* the reference counter is incrementes and the object is returned.
* 2) The object does not exist, but it can be aggregated within
* another object. In that case, user ops->delta_create() is called
* to obtain delta data and a new object is created with returned
* user-delta private pointer.
* 3) The object does not exist and cannot be aggregated into
* any of the existing objects. In that case, user ops->root_create()
* is called to create the root and a new object is created with
* returned user-root private pointer.
*
* Returns a pointer to objagg object instance in case of success,
* otherwise it returns pointer error using ERR_PTR macro.
*/
struct objagg_obj *objagg_obj_get(struct objagg *objagg, void *obj)
{
struct objagg_obj *objagg_obj;
objagg_obj = __objagg_obj_get(objagg, obj);
if (IS_ERR(objagg_obj))
return objagg_obj;
objagg_obj_stats_inc(objagg_obj);
trace_objagg_obj_get(objagg, objagg_obj, objagg_obj->refcount);
return objagg_obj;
}
EXPORT_SYMBOL(objagg_obj_get);
static void objagg_obj_destroy(struct objagg *objagg,
struct objagg_obj *objagg_obj)
{
trace_objagg_obj_destroy(objagg, objagg_obj);
--objagg->obj_count;
list_del(&objagg_obj->list);
rhashtable_remove_fast(&objagg->obj_ht, &objagg_obj->ht_node,
objagg->ht_params);
objagg_obj_fini(objagg, objagg_obj);
kfree(objagg_obj);
}
static void __objagg_obj_put(struct objagg *objagg,
struct objagg_obj *objagg_obj)
{
if (!objagg_obj_ref_dec(objagg_obj))
objagg_obj_destroy(objagg, objagg_obj);
}
/**
* objagg_obj_put - puts an object within objagg instance
* @objagg: objagg instance
* @objagg_obj: objagg object instance
*
* Note: all locking must be provided by the caller.
*
* Symmetric to objagg_obj_get().
*/
void objagg_obj_put(struct objagg *objagg, struct objagg_obj *objagg_obj)
{
trace_objagg_obj_put(objagg, objagg_obj, objagg_obj->refcount);
objagg_obj_stats_dec(objagg_obj);
__objagg_obj_put(objagg, objagg_obj);
}
EXPORT_SYMBOL(objagg_obj_put);
/**
* objagg_create - creates a new objagg instance
* @ops: user-specific callbacks
* @priv: pointer to a private data passed to the ops
*
* Note: all locking must be provided by the caller.
*
* The purpose of the library is to provide an infrastructure to
* aggregate user-specified objects. Library does not care about the type
* of the object. User fills-up ops which take care of the specific
* user object manipulation.
*
* As a very stupid example, consider integer numbers. For example
* number 8 as a root object. That can aggregate number 9 with delta 1,
* number 10 with delta 2, etc. This example is implemented as
* a part of a testing module in test_objagg.c file.
*
* Each objagg instance contains multiple trees. Each tree node is
* represented by "an object". In the current implementation there can be
* only roots and leafs nodes. Leaf nodes are called deltas.
* But in general, this can be easily extended for intermediate nodes.
* In that extension, a delta would be associated with all non-root
* nodes.
*
* Returns a pointer to newly created objagg instance in case of success,
* otherwise it returns pointer error using ERR_PTR macro.
*/
struct objagg *objagg_create(const struct objagg_ops *ops, void *priv)
{
struct objagg *objagg;
int err;
if (WARN_ON(!ops || !ops->root_create || !ops->root_destroy ||
!ops->delta_create || !ops->delta_destroy))
return ERR_PTR(-EINVAL);
objagg = kzalloc(sizeof(*objagg), GFP_KERNEL);
if (!objagg)
return ERR_PTR(-ENOMEM);
objagg->ops = ops;
objagg->priv = priv;
INIT_LIST_HEAD(&objagg->obj_list);
objagg->ht_params.key_len = ops->obj_size;
objagg->ht_params.key_offset = offsetof(struct objagg_obj, obj);
objagg->ht_params.head_offset = offsetof(struct objagg_obj, ht_node);
err = rhashtable_init(&objagg->obj_ht, &objagg->ht_params);
if (err)
goto err_rhashtable_init;
trace_objagg_create(objagg);
return objagg;
err_rhashtable_init:
kfree(objagg);
return ERR_PTR(err);
}
EXPORT_SYMBOL(objagg_create);
/**
* objagg_destroy - destroys a new objagg instance
* @objagg: objagg instance
*
* Note: all locking must be provided by the caller.
*/
void objagg_destroy(struct objagg *objagg)
{
trace_objagg_destroy(objagg);
WARN_ON(!list_empty(&objagg->obj_list));
rhashtable_destroy(&objagg->obj_ht);
kfree(objagg);
}
EXPORT_SYMBOL(objagg_destroy);
static int objagg_stats_info_sort_cmp_func(const void *a, const void *b)
{
const struct objagg_obj_stats_info *stats_info1 = a;
const struct objagg_obj_stats_info *stats_info2 = b;
if (stats_info1->is_root != stats_info2->is_root)
return stats_info2->is_root - stats_info1->is_root;
if (stats_info1->stats.delta_user_count !=
stats_info2->stats.delta_user_count)
return stats_info2->stats.delta_user_count -
stats_info1->stats.delta_user_count;
return stats_info2->stats.user_count - stats_info1->stats.user_count;
}
/**
* objagg_stats_get - obtains stats of the objagg instance
* @objagg: objagg instance
*
* Note: all locking must be provided by the caller.
*
* The returned structure contains statistics of all object
* currently in use, ordered by following rules:
* 1) Root objects are always on lower indexes than the rest.
* 2) Objects with higher delta user count are always on lower
* indexes.
* 3) In case more objects have the same delta user count,
* the objects are ordered by user count.
*
* Returns a pointer to stats instance in case of success,
* otherwise it returns pointer error using ERR_PTR macro.
*/
const struct objagg_stats *objagg_stats_get(struct objagg *objagg)
{
struct objagg_stats *objagg_stats;
struct objagg_obj *objagg_obj;
size_t alloc_size;
int i;
alloc_size = sizeof(*objagg_stats) +
sizeof(objagg_stats->stats_info[0]) * objagg->obj_count;
objagg_stats = kzalloc(alloc_size, GFP_KERNEL);
if (!objagg_stats)
return ERR_PTR(-ENOMEM);
i = 0;
list_for_each_entry(objagg_obj, &objagg->obj_list, list) {
memcpy(&objagg_stats->stats_info[i].stats, &objagg_obj->stats,
sizeof(objagg_stats->stats_info[0].stats));
objagg_stats->stats_info[i].objagg_obj = objagg_obj;
objagg_stats->stats_info[i].is_root =
objagg_obj_is_root(objagg_obj);
i++;
}
objagg_stats->stats_info_count = i;
sort(objagg_stats->stats_info, objagg_stats->stats_info_count,
sizeof(struct objagg_obj_stats_info),
objagg_stats_info_sort_cmp_func, NULL);
return objagg_stats;
}
EXPORT_SYMBOL(objagg_stats_get);
/**
* objagg_stats_puts - puts stats of the objagg instance
* @objagg_stats: objagg instance stats
*
* Note: all locking must be provided by the caller.
*/
void objagg_stats_put(const struct objagg_stats *objagg_stats)
{
kfree(objagg_stats);
}
EXPORT_SYMBOL(objagg_stats_put);
MODULE_LICENSE("Dual BSD/GPL");
MODULE_AUTHOR("Jiri Pirko <jiri@mellanox.com>");
MODULE_DESCRIPTION("Object aggregation manager");