linux/include/drm/drm_hashtab.h
Thomas Hellstrom 384cc2f968 drm: Add a hash-tab rcu-safe API
While hashtab should now be RCU-safe, Add a drm_ht_xxx_api for consumers
to use to make it obvious what locking mechanism is used.

Document the way the rcu-safe interface should be used.

Don't use rcu-safe list traversal in modify operations where we should use
a spinlock / mutex anyway.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2012-11-28 18:36:05 +10:00

79 lines
3.1 KiB
C

/**************************************************************************
*
* Copyright 2006 Tungsten Graphics, Inc., Bismack, ND. USA.
* All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sub license, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice (including the
* next paragraph) shall be included in all copies or substantial portions
* of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
* THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
* DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
* OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
* USE OR OTHER DEALINGS IN THE SOFTWARE.
*
*
**************************************************************************/
/*
* Simple open hash tab implementation.
*
* Authors:
* Thomas Hellström <thomas-at-tungstengraphics-dot-com>
*/
#ifndef DRM_HASHTAB_H
#define DRM_HASHTAB_H
#include <linux/list.h>
#define drm_hash_entry(_ptr, _type, _member) container_of(_ptr, _type, _member)
struct drm_hash_item {
struct hlist_node head;
unsigned long key;
};
struct drm_open_hash {
struct hlist_head *table;
u8 order;
};
extern int drm_ht_create(struct drm_open_hash *ht, unsigned int order);
extern int drm_ht_insert_item(struct drm_open_hash *ht, struct drm_hash_item *item);
extern int drm_ht_just_insert_please(struct drm_open_hash *ht, struct drm_hash_item *item,
unsigned long seed, int bits, int shift,
unsigned long add);
extern int drm_ht_find_item(struct drm_open_hash *ht, unsigned long key, struct drm_hash_item **item);
extern void drm_ht_verbose_list(struct drm_open_hash *ht, unsigned long key);
extern int drm_ht_remove_key(struct drm_open_hash *ht, unsigned long key);
extern int drm_ht_remove_item(struct drm_open_hash *ht, struct drm_hash_item *item);
extern void drm_ht_remove(struct drm_open_hash *ht);
/*
* RCU-safe interface
*
* The user of this API needs to make sure that two or more instances of the
* hash table manipulation functions are never run simultaneously.
* The lookup function drm_ht_find_item_rcu may, however, run simultaneously
* with any of the manipulation functions as long as it's called from within
* an RCU read-locked section.
*/
#define drm_ht_insert_item_rcu drm_ht_insert_item
#define drm_ht_just_insert_please_rcu drm_ht_just_insert_please
#define drm_ht_remove_key_rcu drm_ht_remove_key
#define drm_ht_remove_item_rcu drm_ht_remove_item
#define drm_ht_find_item_rcu drm_ht_find_item
#endif