X-Git-Url: https://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=urcu%2Fstatic%2Frculfstack.h;fp=urcu%2Fstatic%2Frculfstack.h;h=0000000000000000000000000000000000000000;hp=3473ccef82299b0b41559734e75377b2ac0f1941;hb=6893800a4d1cc14dff0395ddcd660a5138db183d;hpb=a59f39055b5ecb77b68cf78b9839aa9e8e4ec332 diff --git a/urcu/static/rculfstack.h b/urcu/static/rculfstack.h deleted file mode 100644 index 3473cce..0000000 --- a/urcu/static/rculfstack.h +++ /dev/null @@ -1,128 +0,0 @@ -#ifndef _URCU_RCULFSTACK_STATIC_H -#define _URCU_RCULFSTACK_STATIC_H - -/* - * rculfstack-static.h - * - * Userspace RCU library - Lock-Free RCU Stack - * - * Copyright 2010 - Mathieu Desnoyers - * - * TO BE INCLUDED ONLY IN LGPL-COMPATIBLE CODE. See rculfstack.h for linking - * dynamically with the userspace rcu library. - * - * This library is free software; you can redistribute it and/or - * modify it under the terms of the GNU Lesser General Public - * License as published by the Free Software Foundation; either - * version 2.1 of the License, or (at your option) any later version. - * - * This library 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 - * Lesser General Public License for more details. - * - * You should have received a copy of the GNU Lesser General Public - * License along with this library; if not, write to the Free Software - * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA - */ - -#include -#include - -#ifdef __cplusplus -extern "C" { -#endif - -static inline -void _cds_lfs_node_init_rcu(struct cds_lfs_node_rcu *node) -{ -} - -static inline -void _cds_lfs_init_rcu(struct cds_lfs_stack_rcu *s) -{ - s->head = NULL; -} - -/* - * Lock-free stack push is not subject to ABA problem, so no need to - * take the RCU read-side lock. Even if "head" changes between two - * uatomic_cmpxchg() invocations here (being popped, and then pushed - * again by one or more concurrent threads), the second - * uatomic_cmpxchg() invocation only cares about pushing a new entry at - * the head of the stack, ensuring consistency by making sure the new - * node->next is the same pointer value as the value replaced as head. - * It does not care about the content of the actual next node, so it can - * very well be reallocated between the two uatomic_cmpxchg(). - * - * We take the approach of expecting the stack to be usually empty, so - * we first try an initial uatomic_cmpxchg() on a NULL old_head, and - * retry if the old head was non-NULL (the value read by the first - * uatomic_cmpxchg() is used as old head for the following loop). The - * upside of this scheme is to minimize the amount of cacheline traffic, - * always performing an exclusive cacheline access, rather than doing - * non-exclusive followed by exclusive cacheline access (which would be - * required if we first read the old head value). This design decision - * might be revisited after more throrough benchmarking on various - * platforms. - * - * Returns 0 if the stack was empty prior to adding the node. - * Returns non-zero otherwise. - */ -static inline -int _cds_lfs_push_rcu(struct cds_lfs_stack_rcu *s, - struct cds_lfs_node_rcu *node) -{ - struct cds_lfs_node_rcu *head = NULL; - - for (;;) { - struct cds_lfs_node_rcu *old_head = head; - - node->next = head; - /* - * uatomic_cmpxchg() implicit memory barrier orders earlier - * stores to node before publication. - */ - head = uatomic_cmpxchg(&s->head, old_head, node); - if (old_head == head) - break; - } - return (int) !!((unsigned long) head); -} - -/* - * Should be called under rcu read-side lock. - * - * The caller must wait for a grace period to pass before freeing the returned - * node or modifying the cds_lfs_node_rcu structure. - * Returns NULL if stack is empty. - */ -static inline -struct cds_lfs_node_rcu * -_cds_lfs_pop_rcu(struct cds_lfs_stack_rcu *s) -{ - for (;;) { - struct cds_lfs_node_rcu *head; - - head = rcu_dereference(s->head); - if (head) { - struct cds_lfs_node_rcu *next = rcu_dereference(head->next); - - if (uatomic_cmpxchg(&s->head, head, next) == head) { - return head; - } else { - /* Concurrent modification. Retry. */ - continue; - } - } else { - /* Empty stack */ - return NULL; - } - } -} - -#ifdef __cplusplus -} -#endif - -#endif /* _URCU_RCULFSTACK_STATIC_H */