diff options
Diffstat (limited to 'libdde-linux26/contrib/include/linux/radix-tree.h')
| -rw-r--r-- | libdde-linux26/contrib/include/linux/radix-tree.h | 193 |
1 files changed, 193 insertions, 0 deletions
diff --git a/libdde-linux26/contrib/include/linux/radix-tree.h b/libdde-linux26/contrib/include/linux/radix-tree.h new file mode 100644 index 00000000..355f6e80 --- /dev/null +++ b/libdde-linux26/contrib/include/linux/radix-tree.h @@ -0,0 +1,193 @@ +/* + * Copyright (C) 2001 Momchil Velikov + * Portions Copyright (C) 2001 Christoph Hellwig + * Copyright (C) 2006 Nick Piggin + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation; either version 2, or (at + * your option) any later version. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + */ +#ifndef _LINUX_RADIX_TREE_H +#define _LINUX_RADIX_TREE_H + +#include <linux/preempt.h> +#include <linux/types.h> +#include <linux/kernel.h> +#include <linux/rcupdate.h> + +/* + * An indirect pointer (root->rnode pointing to a radix_tree_node, rather + * than a data item) is signalled by the low bit set in the root->rnode + * pointer. + * + * In this case root->height is > 0, but the indirect pointer tests are + * needed for RCU lookups (because root->height is unreliable). The only + * time callers need worry about this is when doing a lookup_slot under + * RCU. + */ +#define RADIX_TREE_INDIRECT_PTR 1 +#define RADIX_TREE_RETRY ((void *)-1UL) + +static inline void *radix_tree_ptr_to_indirect(void *ptr) +{ + return (void *)((unsigned long)ptr | RADIX_TREE_INDIRECT_PTR); +} + +static inline void *radix_tree_indirect_to_ptr(void *ptr) +{ + return (void *)((unsigned long)ptr & ~RADIX_TREE_INDIRECT_PTR); +} + +static inline int radix_tree_is_indirect_ptr(void *ptr) +{ + return (int)((unsigned long)ptr & RADIX_TREE_INDIRECT_PTR); +} + +/*** radix-tree API starts here ***/ + +#define RADIX_TREE_MAX_TAGS 2 + +/* root tags are stored in gfp_mask, shifted by __GFP_BITS_SHIFT */ +struct radix_tree_root { + unsigned int height; + gfp_t gfp_mask; + struct radix_tree_node *rnode; +}; + +#define RADIX_TREE_INIT(mask) { \ + .height = 0, \ + .gfp_mask = (mask), \ + .rnode = NULL, \ +} + +#define RADIX_TREE(name, mask) \ + struct radix_tree_root name = RADIX_TREE_INIT(mask) + +#define INIT_RADIX_TREE(root, mask) \ +do { \ + (root)->height = 0; \ + (root)->gfp_mask = (mask); \ + (root)->rnode = NULL; \ +} while (0) + +/** + * Radix-tree synchronization + * + * The radix-tree API requires that users provide all synchronisation (with + * specific exceptions, noted below). + * + * Synchronization of access to the data items being stored in the tree, and + * management of their lifetimes must be completely managed by API users. + * + * For API usage, in general, + * - any function _modifying_ the tree or tags (inserting or deleting + * items, setting or clearing tags) must exclude other modifications, and + * exclude any functions reading the tree. + * - any function _reading_ the tree or tags (looking up items or tags, + * gang lookups) must exclude modifications to the tree, but may occur + * concurrently with other readers. + * + * The notable exceptions to this rule are the following functions: + * radix_tree_lookup + * radix_tree_lookup_slot + * radix_tree_tag_get + * radix_tree_gang_lookup + * radix_tree_gang_lookup_slot + * radix_tree_gang_lookup_tag + * radix_tree_gang_lookup_tag_slot + * radix_tree_tagged + * + * The first 7 functions are able to be called locklessly, using RCU. The + * caller must ensure calls to these functions are made within rcu_read_lock() + * regions. Other readers (lock-free or otherwise) and modifications may be + * running concurrently. + * + * It is still required that the caller manage the synchronization and lifetimes + * of the items. So if RCU lock-free lookups are used, typically this would mean + * that the items have their own locks, or are amenable to lock-free access; and + * that the items are freed by RCU (or only freed after having been deleted from + * the radix tree *and* a synchronize_rcu() grace period). + * + * (Note, rcu_assign_pointer and rcu_dereference are not needed to control + * access to data items when inserting into or looking up from the radix tree) + * + * radix_tree_tagged is able to be called without locking or RCU. + */ + +/** + * radix_tree_deref_slot - dereference a slot + * @pslot: pointer to slot, returned by radix_tree_lookup_slot + * Returns: item that was stored in that slot with any direct pointer flag + * removed. + * + * For use with radix_tree_lookup_slot(). Caller must hold tree at least read + * locked across slot lookup and dereference. More likely, will be used with + * radix_tree_replace_slot(), as well, so caller will hold tree write locked. + */ +static inline void *radix_tree_deref_slot(void **pslot) +{ + void *ret = rcu_dereference(*pslot); + if (unlikely(radix_tree_is_indirect_ptr(ret))) + ret = RADIX_TREE_RETRY; + return ret; +} +/** + * radix_tree_replace_slot - replace item in a slot + * @pslot: pointer to slot, returned by radix_tree_lookup_slot + * @item: new item to store in the slot. + * + * For use with radix_tree_lookup_slot(). Caller must hold tree write locked + * across slot lookup and replacement. + */ +static inline void radix_tree_replace_slot(void **pslot, void *item) +{ + BUG_ON(radix_tree_is_indirect_ptr(item)); + rcu_assign_pointer(*pslot, item); +} + +int radix_tree_insert(struct radix_tree_root *, unsigned long, void *); +void *radix_tree_lookup(struct radix_tree_root *, unsigned long); +void **radix_tree_lookup_slot(struct radix_tree_root *, unsigned long); +void *radix_tree_delete(struct radix_tree_root *, unsigned long); +unsigned int +radix_tree_gang_lookup(struct radix_tree_root *root, void **results, + unsigned long first_index, unsigned int max_items); +unsigned int +radix_tree_gang_lookup_slot(struct radix_tree_root *root, void ***results, + unsigned long first_index, unsigned int max_items); +unsigned long radix_tree_next_hole(struct radix_tree_root *root, + unsigned long index, unsigned long max_scan); +int radix_tree_preload(gfp_t gfp_mask); +void radix_tree_init(void); +void *radix_tree_tag_set(struct radix_tree_root *root, + unsigned long index, unsigned int tag); +void *radix_tree_tag_clear(struct radix_tree_root *root, + unsigned long index, unsigned int tag); +int radix_tree_tag_get(struct radix_tree_root *root, + unsigned long index, unsigned int tag); +unsigned int +radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results, + unsigned long first_index, unsigned int max_items, + unsigned int tag); +unsigned int +radix_tree_gang_lookup_tag_slot(struct radix_tree_root *root, void ***results, + unsigned long first_index, unsigned int max_items, + unsigned int tag); +int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag); + +static inline void radix_tree_preload_end(void) +{ + preempt_enable(); +} + +#endif /* _LINUX_RADIX_TREE_H */ |