From: Mathieu Desnoyers Date: Fri, 1 Aug 2014 00:01:57 +0000 (-0400) Subject: lfstack: Implement mutex-free stack head with transparent union (v2) X-Git-Tag: v0.9.0~82 X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=48a8832be16833b1a9f2625799ac3d0ea4dafc91;p=urcu.git lfstack: Implement mutex-free stack head with transparent union (v2) Changes since v1: - implement __cds_lfs_init(). Tested-by: Eric Wong CC: "Paul E. McKenney" CC: "Lai Jiangshan" Signed-off-by: Mathieu Desnoyers --- diff --git a/lfstack.c b/lfstack.c index db2c2cf..3dac178 100644 --- a/lfstack.c +++ b/lfstack.c @@ -40,12 +40,17 @@ void cds_lfs_init(struct cds_lfs_stack *s) _cds_lfs_init(s); } -bool cds_lfs_empty(struct cds_lfs_stack *s) +void __cds_lfs_init(struct __cds_lfs_stack *s) +{ + ___cds_lfs_init(s); +} + +bool cds_lfs_empty(cds_lfs_stack_ptr_t s) { return _cds_lfs_empty(s); } -bool cds_lfs_push(struct cds_lfs_stack *s, struct cds_lfs_node *node) +bool cds_lfs_push(cds_lfs_stack_ptr_t s, struct cds_lfs_node *node) { return _cds_lfs_push(s, node); } @@ -70,12 +75,12 @@ void cds_lfs_pop_unlock(struct cds_lfs_stack *s) _cds_lfs_pop_unlock(s); } -struct cds_lfs_node *__cds_lfs_pop(struct cds_lfs_stack *s) +struct cds_lfs_node *__cds_lfs_pop(cds_lfs_stack_ptr_t s) { return ___cds_lfs_pop(s); } -struct cds_lfs_head *__cds_lfs_pop_all(struct cds_lfs_stack *s) +struct cds_lfs_head *__cds_lfs_pop_all(cds_lfs_stack_ptr_t s) { return ___cds_lfs_pop_all(s); } diff --git a/urcu/lfstack.h b/urcu/lfstack.h index eddff0e..9f384d6 100644 --- a/urcu/lfstack.h +++ b/urcu/lfstack.h @@ -70,11 +70,25 @@ struct cds_lfs_head { struct cds_lfs_node node; }; +struct __cds_lfs_stack { + struct cds_lfs_head *head; +}; + struct cds_lfs_stack { struct cds_lfs_head *head; pthread_mutex_t lock; }; +/* + * The transparent union allows calling functions that work on both + * struct cds_lfs_stack and struct __cds_lfs_stack on any of those two + * types. + */ +typedef union __attribute__((__transparent_union__)) { + struct __cds_lfs_stack *_s; + struct cds_lfs_stack *s; +} cds_lfs_stack_ptr_t; + #ifdef _LGPL_SOURCE #include @@ -108,12 +122,17 @@ extern void cds_lfs_node_init(struct cds_lfs_node *node); */ extern void cds_lfs_init(struct cds_lfs_stack *s); +/* + * __cds_lfs_init: initialize lock-free stack. + */ +extern void __cds_lfs_init(struct __cds_lfs_stack *s); + /* * cds_lfs_empty: return whether lock-free stack is empty. * * No memory barrier is issued. No mutual exclusion is required. */ -extern bool cds_lfs_empty(struct cds_lfs_stack *s); +extern bool cds_lfs_empty(cds_lfs_stack_ptr_t s); /* * cds_lfs_push: push a node into the stack. @@ -123,7 +142,7 @@ extern bool cds_lfs_empty(struct cds_lfs_stack *s); * Returns 0 if the stack was empty prior to adding the node. * Returns non-zero otherwise. */ -extern bool cds_lfs_push(struct cds_lfs_stack *s, +extern bool cds_lfs_push(cds_lfs_stack_ptr_t s, struct cds_lfs_node *node); /* @@ -166,7 +185,7 @@ extern void cds_lfs_pop_unlock(struct cds_lfs_stack *s); * 3) Ensuring that only ONE thread can call __cds_lfs_pop() and * __cds_lfs_pop_all(). (multi-provider/single-consumer scheme). */ -extern struct cds_lfs_node *__cds_lfs_pop(struct cds_lfs_stack *s); +extern struct cds_lfs_node *__cds_lfs_pop(cds_lfs_stack_ptr_t s); /* * __cds_lfs_pop_all: pop all nodes from a stack. @@ -185,7 +204,7 @@ extern struct cds_lfs_node *__cds_lfs_pop(struct cds_lfs_stack *s); * 3) Ensuring that only ONE thread can call __cds_lfs_pop() and * __cds_lfs_pop_all(). (multi-provider/single-consumer scheme). */ -extern struct cds_lfs_head *__cds_lfs_pop_all(struct cds_lfs_stack *s); +extern struct cds_lfs_head *__cds_lfs_pop_all(cds_lfs_stack_ptr_t s); #endif /* !_LGPL_SOURCE */ diff --git a/urcu/static/lfstack.h b/urcu/static/lfstack.h index 0be9594..63af91a 100644 --- a/urcu/static/lfstack.h +++ b/urcu/static/lfstack.h @@ -78,6 +78,15 @@ void _cds_lfs_init(struct cds_lfs_stack *s) assert(!ret); } +/* + * ___cds_lfs_init: initialize lock-free stack. + */ +static inline +void ___cds_lfs_init(struct __cds_lfs_stack *s) +{ + s->head = NULL; +} + static inline bool ___cds_lfs_empty_head(struct cds_lfs_head *head) { @@ -90,9 +99,9 @@ bool ___cds_lfs_empty_head(struct cds_lfs_head *head) * No memory barrier is issued. No mutual exclusion is required. */ static inline -bool _cds_lfs_empty(struct cds_lfs_stack *s) +bool _cds_lfs_empty(cds_lfs_stack_ptr_t s) { - return ___cds_lfs_empty_head(CMM_LOAD_SHARED(s->head)); + return ___cds_lfs_empty_head(CMM_LOAD_SHARED(s._s->head)); } /* @@ -125,9 +134,10 @@ bool _cds_lfs_empty(struct cds_lfs_stack *s) * Returns non-zero otherwise. */ static inline -bool _cds_lfs_push(struct cds_lfs_stack *s, +bool _cds_lfs_push(cds_lfs_stack_ptr_t u_s, struct cds_lfs_node *node) { + struct __cds_lfs_stack *s = u_s._s; struct cds_lfs_head *head = NULL; struct cds_lfs_head *new_head = caa_container_of(node, struct cds_lfs_head, node); @@ -168,8 +178,10 @@ bool _cds_lfs_push(struct cds_lfs_stack *s, * __cds_lfs_pop_all(). (multi-provider/single-consumer scheme). */ static inline -struct cds_lfs_node *___cds_lfs_pop(struct cds_lfs_stack *s) +struct cds_lfs_node *___cds_lfs_pop(cds_lfs_stack_ptr_t u_s) { + struct __cds_lfs_stack *s = u_s._s; + for (;;) { struct cds_lfs_head *head, *next_head; struct cds_lfs_node *next; @@ -211,8 +223,10 @@ struct cds_lfs_node *___cds_lfs_pop(struct cds_lfs_stack *s) * __cds_lfs_pop_all(). (multi-provider/single-consumer scheme). */ static inline -struct cds_lfs_head *___cds_lfs_pop_all(struct cds_lfs_stack *s) +struct cds_lfs_head *___cds_lfs_pop_all(cds_lfs_stack_ptr_t u_s) { + struct __cds_lfs_stack *s = u_s._s; + /* * Implicit memory barrier after uatomic_xchg() matches implicit * memory barrier before uatomic_cmpxchg() in cds_lfs_push. It