* Mathieu Desnoyers ([email protected]) wrote:
> Signed-off-by: Mathieu Desnoyers <[email protected]>
I'll merge this patch into master, let me know if anything seems broken
and I'll do the appropriate follow-up.
Thanks,
Mathieu
> ---
> diff --git a/urcu/static/wfstack.h b/urcu/static/wfstack.h
> index 018a121..9bc9519 100644
> --- a/urcu/static/wfstack.h
> +++ b/urcu/static/wfstack.h
> @@ -137,7 +137,7 @@ int _cds_wfs_push(struct cds_wfs_stack *s, struct
> cds_wfs_node *node)
> * Waiting for push to complete enqueue and return the next node.
> */
> static inline struct cds_wfs_node *
> -___cds_wfs_node_sync_next(struct cds_wfs_node *node)
> +___cds_wfs_node_sync_next(struct cds_wfs_node *node, int blocking)
> {
> struct cds_wfs_node *next;
> int attempt = 0;
> @@ -146,6 +146,8 @@ ___cds_wfs_node_sync_next(struct cds_wfs_node *node)
> * Adaptative busy-looping waiting for push to complete.
> */
> while ((next = CMM_LOAD_SHARED(node->next)) == NULL) {
> + if (!blocking)
> + return CDS_WFS_WOULDBLOCK;
> if (++attempt >= CDS_WFS_ADAPT_ATTEMPTS) {
> poll(NULL, 0, CDS_WFS_WAIT); /* Wait for 10ms */
> attempt = 0;
> @@ -157,6 +159,29 @@ ___cds_wfs_node_sync_next(struct cds_wfs_node *node)
> return next;
> }
>
> +static inline
> +struct cds_wfs_node *
> +___cds_wfs_pop(struct cds_wfs_stack *s, int blocking)
> +{
> + struct cds_wfs_head *head, *new_head;
> + struct cds_wfs_node *next;
> +
> + for (;;) {
> + head = CMM_LOAD_SHARED(s->head);
> + if (___cds_wfs_end(head))
> + return NULL;
> + next = ___cds_wfs_node_sync_next(&head->node, blocking);
> + if (!blocking && next == CDS_WFS_WOULDBLOCK)
> + return CDS_WFS_WOULDBLOCK;
> + new_head = caa_container_of(next, struct cds_wfs_head, node);
> + if (uatomic_cmpxchg(&s->head, head, new_head) == head)
> + return &head->node;
> + if (!blocking)
> + return CDS_WFS_WOULDBLOCK;
> + /* busy-loop if head changed under us */
> + }
> +}
> +
> /*
> * __cds_wfs_pop_blocking: pop a node from the stack.
> *
> @@ -177,19 +202,20 @@ static inline
> struct cds_wfs_node *
> ___cds_wfs_pop_blocking(struct cds_wfs_stack *s)
> {
> - struct cds_wfs_head *head, *new_head;
> - struct cds_wfs_node *next;
> + return ___cds_wfs_pop(s, 1);
> +}
>
> - for (;;) {
> - head = CMM_LOAD_SHARED(s->head);
> - if (___cds_wfs_end(head))
> - return NULL;
> - next = ___cds_wfs_node_sync_next(&head->node);
> - new_head = caa_container_of(next, struct cds_wfs_head, node);
> - if (uatomic_cmpxchg(&s->head, head, new_head) == head)
> - return &head->node;
> - /* busy-loop if head changed under us */
> - }
> +/*
> + * __cds_wfs_pop_nonblocking: pop a node from the stack.
> + *
> + * Same as __cds_wfs_pop_blocking, but returns CDS_WFS_WOULDBLOCK if
> + * it needs to block.
> + */
> +static inline
> +struct cds_wfs_node *
> +___cds_wfs_pop_nonblocking(struct cds_wfs_stack *s)
> +{
> + return ___cds_wfs_pop(s, 0);
> }
>
> /*
> @@ -303,6 +329,22 @@ _cds_wfs_first(struct cds_wfs_head *head)
> return &head->node;
> }
>
> +static inline struct cds_wfs_node *
> +___cds_wfs_next(struct cds_wfs_node *node, int blocking)
> +{
> + struct cds_wfs_node *next;
> +
> + next = ___cds_wfs_node_sync_next(node, blocking);
> + /*
> + * CDS_WFS_WOULDBLOCK != CSD_WFS_END, so we can check for end
> + * even if ___cds_wfs_node_sync_next returns CDS_WFS_WOULDBLOCK,
> + * and still return CDS_WFS_WOULDBLOCK.
> + */
> + if (___cds_wfs_end(next))
> + return NULL;
> + return next;
> +}
> +
> /*
> * cds_wfs_next_blocking: get next node of a popped stack.
> *
> @@ -319,12 +361,20 @@ _cds_wfs_first(struct cds_wfs_head *head)
> static inline struct cds_wfs_node *
> _cds_wfs_next_blocking(struct cds_wfs_node *node)
> {
> - struct cds_wfs_node *next;
> + return ___cds_wfs_next(node, 1);
> +}
>
> - next = ___cds_wfs_node_sync_next(node);
> - if (___cds_wfs_end(next))
> - return NULL;
> - return next;
> +
> +/*
> + * cds_wfs_next_nonblocking: get next node of a popped stack.
> + *
> + * Same as cds_wfs_next_blocking, but returns CDS_WFS_WOULDBLOCK if it
> + * needs to block.
> + */
> +static inline struct cds_wfs_node *
> +_cds_wfs_next_nonblocking(struct cds_wfs_node *node)
> +{
> + return ___cds_wfs_next(node, 0);
> }
>
> #ifdef __cplusplus
> diff --git a/urcu/wfstack.h b/urcu/wfstack.h
> index 0e435ba..03fee8f 100644
> --- a/urcu/wfstack.h
> +++ b/urcu/wfstack.h
> @@ -58,6 +58,8 @@ extern "C" {
> * synchronization.
> */
>
> +#define CDS_WFS_WOULDBLOCK ((void *) -1UL)
> +
> /*
> * struct cds_wfs_node is returned by __cds_wfs_pop, and also used as
> * iterator on stack. It is not safe to dereference the node next
> @@ -184,6 +186,14 @@ extern struct cds_wfs_node *cds_wfs_first(struct
> cds_wfs_head *head);
> extern struct cds_wfs_node *cds_wfs_next_blocking(struct cds_wfs_node *node);
>
> /*
> + * cds_wfs_next_nonblocking: get next node of a popped stack.
> + *
> + * Same as cds_wfs_next_blocking, but returns CDS_WFS_WOULDBLOCK if it
> + * needs to block.
> + */
> +extern struct cds_wfs_node *cds_wfs_next_nonblocking(struct cds_wfs_node
> *node);
> +
> +/*
> * cds_wfs_pop_lock: lock stack pop-protection mutex.
> */
> extern void cds_wfs_pop_lock(struct cds_wfs_stack *s);
> @@ -212,6 +222,14 @@ extern void cds_wfs_pop_unlock(struct cds_wfs_stack *s);
> extern struct cds_wfs_node *__cds_wfs_pop_blocking(struct cds_wfs_stack *s);
>
> /*
> + * __cds_wfs_pop_nonblocking: pop a node from the stack.
> + *
> + * Same as __cds_wfs_pop_blocking, but returns CDS_WFS_WOULDBLOCK if
> + * it needs to block.
> + */
> +extern struct cds_wfs_node *__cds_wfs_pop_nonblocking(struct cds_wfs_stack
> *s);
> +
> +/*
> * __cds_wfs_pop_all: pop all nodes from a stack.
> *
> * __cds_wfs_pop_all does not require any synchronization with other
> diff --git a/wfstack.c b/wfstack.c
> index f0bae57..4ccb6b9 100644
> --- a/wfstack.c
> +++ b/wfstack.c
> @@ -68,6 +68,11 @@ struct cds_wfs_node *cds_wfs_next_blocking(struct
> cds_wfs_node *node)
> return _cds_wfs_next_blocking(node);
> }
>
> +struct cds_wfs_node *cds_wfs_next_nonblocking(struct cds_wfs_node *node)
> +{
> + return _cds_wfs_next_nonblocking(node);
> +}
> +
> void cds_wfs_pop_lock(struct cds_wfs_stack *s)
> {
> _cds_wfs_pop_lock(s);
> @@ -83,6 +88,11 @@ struct cds_wfs_node *__cds_wfs_pop_blocking(struct
> cds_wfs_stack *s)
> return ___cds_wfs_pop_blocking(s);
> }
>
> +struct cds_wfs_node *__cds_wfs_pop_nonblocking(struct cds_wfs_stack *s)
> +{
> + return ___cds_wfs_pop_nonblocking(s);
> +}
> +
> struct cds_wfs_head *__cds_wfs_pop_all(struct cds_wfs_stack *s)
> {
> return ___cds_wfs_pop_all(s);
>
> --
> Mathieu Desnoyers
> Operating System Efficiency R&D Consultant
> EfficiOS Inc.
> http://www.efficios.com
>
> _______________________________________________
> lttng-dev mailing list
> [email protected]
> http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
--
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com
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