rte_ring.h

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/*-
 *   BSD LICENSE
 *
 *   Copyright(c) 2010-2017 Intel Corporation. All rights reserved.
 *   All rights reserved.
 *
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 *   modification, are permitted provided that the following conditions
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 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
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 *       notice, this list of conditions and the following disclaimer in
 *       the documentation and/or other materials provided with the
 *       distribution.
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 *       contributors may be used to endorse or promote products derived
 *       from this software without specific prior written permission.
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 *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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/*
 * Derived from FreeBSD's bufring.h
 *
 **************************************************************************
 *
 * Copyright (c) 2007-2009 Kip Macy kmacy@freebsd.org
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 * 2. The name of Kip Macy nor the names of other
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 ***************************************************************************/

#ifndef _RTE_RING_H_
#define _RTE_RING_H_

#ifdef __cplusplus
extern "C" {
#endif

#include <stdio.h>
#include <stdint.h>
#include <sys/queue.h>
#include <errno.h>
#include <rte_common.h>
#include <rte_memory.h>
#include <rte_lcore.h>
#include <rte_atomic.h>
#include <rte_branch_prediction.h>
#include <rte_memzone.h>

#define RTE_TAILQ_RING_NAME "RTE_RING"

enum rte_ring_queue_behavior {
        RTE_RING_QUEUE_FIXED = 0, /* Enq/Deq a fixed number of items from a ring */
        RTE_RING_QUEUE_VARIABLE   /* Enq/Deq as many items as possible from ring */
};

#define RTE_RING_MZ_PREFIX "RG_"

#define RTE_RING_NAMESIZE (RTE_MEMZONE_NAMESIZE - \
                           sizeof(RTE_RING_MZ_PREFIX) + 1)

struct rte_memzone; /* forward declaration, so as not to require memzone.h */

#if RTE_CACHE_LINE_SIZE < 128
#define PROD_ALIGN (RTE_CACHE_LINE_SIZE * 2)
#define CONS_ALIGN (RTE_CACHE_LINE_SIZE * 2)
#else
#define PROD_ALIGN RTE_CACHE_LINE_SIZE
#define CONS_ALIGN RTE_CACHE_LINE_SIZE
#endif

/* structure to hold a pair of head/tail values and other metadata */
struct rte_ring_headtail {
        volatile uint32_t head;  
        volatile uint32_t tail;  
        uint32_t single;         
};

struct rte_ring {
        /*
         * Note: this field kept the RTE_MEMZONE_NAMESIZE size due to ABI
         * compatibility requirements, it could be changed to RTE_RING_NAMESIZE
         * next time the ABI changes
         */
        char name[RTE_MEMZONE_NAMESIZE] __rte_cache_aligned; 
        int flags;               
        const struct rte_memzone *memzone;
        uint32_t size;           
        uint32_t mask;           
        struct rte_ring_headtail prod __rte_aligned(PROD_ALIGN);

        struct rte_ring_headtail cons __rte_aligned(CONS_ALIGN);
};

#define RING_F_SP_ENQ 0x0001 
#define RING_F_SC_DEQ 0x0002 
#define RTE_RING_SZ_MASK  (unsigned)(0x0fffffff) 
/* @internal defines for passing to the enqueue dequeue worker functions */
#define __IS_SP 1
#define __IS_MP 0
#define __IS_SC 1
#define __IS_MC 0

ssize_t rte_ring_get_memsize(unsigned count);

int rte_ring_init(struct rte_ring *r, const char *name, unsigned count,
        unsigned flags);

struct rte_ring *rte_ring_create(const char *name, unsigned count,
                                 int socket_id, unsigned flags);
void rte_ring_free(struct rte_ring *r);

void rte_ring_dump(FILE *f, const struct rte_ring *r);

/* the actual enqueue of pointers on the ring.
 * Placed here since identical code needed in both
 * single and multi producer enqueue functions */
#define ENQUEUE_PTRS(r, ring_start, prod_head, obj_table, n, obj_type) do { \
        unsigned int i; \
        const uint32_t size = (r)->size; \
        uint32_t idx = prod_head & (r)->mask; \
        obj_type *ring = (obj_type *)ring_start; \
        if (likely(idx + n < size)) { \
                for (i = 0; i < (n & ((~(unsigned)0x3))); i+=4, idx+=4) { \
                        ring[idx] = obj_table[i]; \
                        ring[idx+1] = obj_table[i+1]; \
                        ring[idx+2] = obj_table[i+2]; \
                        ring[idx+3] = obj_table[i+3]; \
                } \
                switch (n & 0x3) { \
                case 3: \
                        ring[idx++] = obj_table[i++]; /* fallthrough */ \
                case 2: \
                        ring[idx++] = obj_table[i++]; /* fallthrough */ \
                case 1: \
                        ring[idx++] = obj_table[i++]; \
                } \
        } else { \
                for (i = 0; idx < size; i++, idx++)\
                        ring[idx] = obj_table[i]; \
                for (idx = 0; i < n; i++, idx++) \
                        ring[idx] = obj_table[i]; \
        } \
} while (0)

/* the actual copy of pointers on the ring to obj_table.
 * Placed here since identical code needed in both
 * single and multi consumer dequeue functions */
#define DEQUEUE_PTRS(r, ring_start, cons_head, obj_table, n, obj_type) do { \
        unsigned int i; \
        uint32_t idx = cons_head & (r)->mask; \
        const uint32_t size = (r)->size; \
        obj_type *ring = (obj_type *)ring_start; \
        if (likely(idx + n < size)) { \
                for (i = 0; i < (n & (~(unsigned)0x3)); i+=4, idx+=4) {\
                        obj_table[i] = ring[idx]; \
                        obj_table[i+1] = ring[idx+1]; \
                        obj_table[i+2] = ring[idx+2]; \
                        obj_table[i+3] = ring[idx+3]; \
                } \
                switch (n & 0x3) { \
                case 3: \
                        obj_table[i++] = ring[idx++]; /* fallthrough */ \
                case 2: \
                        obj_table[i++] = ring[idx++]; /* fallthrough */ \
                case 1: \
                        obj_table[i++] = ring[idx++]; \
                } \
        } else { \
                for (i = 0; idx < size; i++, idx++) \
                        obj_table[i] = ring[idx]; \
                for (idx = 0; i < n; i++, idx++) \
                        obj_table[i] = ring[idx]; \
        } \
} while (0)

static inline __attribute__((always_inline)) void
update_tail(struct rte_ring_headtail *ht, uint32_t old_val, uint32_t new_val,
                uint32_t single)
{
        /*
         * If there are other enqueues/dequeues in progress that preceded us,
         * we need to wait for them to complete
         */
        if (!single)
                while (unlikely(ht->tail != old_val))
                        rte_pause();

        ht->tail = new_val;
}

static inline __attribute__((always_inline)) unsigned int
__rte_ring_move_prod_head(struct rte_ring *r, int is_sp,
                unsigned int n, enum rte_ring_queue_behavior behavior,
                uint32_t *old_head, uint32_t *new_head,
                uint32_t *free_entries)
{
        const uint32_t mask = r->mask;
        unsigned int max = n;
        int success;

        do {
                /* Reset n to the initial burst count */
                n = max;

                *old_head = r->prod.head;
                const uint32_t cons_tail = r->cons.tail;
                /* The subtraction is done between two unsigned 32bits value
                 * (the result is always modulo 32 bits even if we have
                 * *old_head > cons_tail). So 'free_entries' is always between 0
                 * and size(ring)-1. */
                *free_entries = (mask + cons_tail - *old_head);

                /* check that we have enough room in ring */
                if (unlikely(n > *free_entries))
                        n = (behavior == RTE_RING_QUEUE_FIXED) ?
                                        0 : *free_entries;

                if (n == 0)
                        return 0;

                *new_head = *old_head + n;
                if (is_sp)
                        r->prod.head = *new_head, success = 1;
                else
                        success = rte_atomic32_cmpset(&r->prod.head,
                                        *old_head, *new_head);
        } while (unlikely(success == 0));
        return n;
}

static inline __attribute__((always_inline)) unsigned int
__rte_ring_do_enqueue(struct rte_ring *r, void * const *obj_table,
                 unsigned int n, enum rte_ring_queue_behavior behavior,
                 int is_sp, unsigned int *free_space)
{
        uint32_t prod_head, prod_next;
        uint32_t free_entries;

        n = __rte_ring_move_prod_head(r, is_sp, n, behavior,
                        &prod_head, &prod_next, &free_entries);
        if (n == 0)
                goto end;

        ENQUEUE_PTRS(r, &r[1], prod_head, obj_table, n, void *);
        rte_smp_wmb();

        update_tail(&r->prod, prod_head, prod_next, is_sp);
end:
        if (free_space != NULL)
                *free_space = free_entries - n;
        return n;
}

static inline __attribute__((always_inline)) unsigned int
__rte_ring_move_cons_head(struct rte_ring *r, int is_sc,
                unsigned int n, enum rte_ring_queue_behavior behavior,
                uint32_t *old_head, uint32_t *new_head,
                uint32_t *entries)
{
        unsigned int max = n;
        int success;

        /* move cons.head atomically */
        do {
                /* Restore n as it may change every loop */
                n = max;

                *old_head = r->cons.head;
                const uint32_t prod_tail = r->prod.tail;
                /* The subtraction is done between two unsigned 32bits value
                 * (the result is always modulo 32 bits even if we have
                 * cons_head > prod_tail). So 'entries' is always between 0
                 * and size(ring)-1. */
                *entries = (prod_tail - *old_head);

                /* Set the actual entries for dequeue */
                if (n > *entries)
                        n = (behavior == RTE_RING_QUEUE_FIXED) ? 0 : *entries;

                if (unlikely(n == 0))
                        return 0;

                *new_head = *old_head + n;
                if (is_sc)
                        r->cons.head = *new_head, success = 1;
                else
                        success = rte_atomic32_cmpset(&r->cons.head, *old_head,
                                        *new_head);
        } while (unlikely(success == 0));
        return n;
}

static inline __attribute__((always_inline)) unsigned int
__rte_ring_do_dequeue(struct rte_ring *r, void **obj_table,
                 unsigned int n, enum rte_ring_queue_behavior behavior,
                 int is_sc, unsigned int *available)
{
        uint32_t cons_head, cons_next;
        uint32_t entries;

        n = __rte_ring_move_cons_head(r, is_sc, n, behavior,
                        &cons_head, &cons_next, &entries);
        if (n == 0)
                goto end;

        DEQUEUE_PTRS(r, &r[1], cons_head, obj_table, n, void *);
        rte_smp_rmb();

        update_tail(&r->cons, cons_head, cons_next, is_sc);

end:
        if (available != NULL)
                *available = entries - n;
        return n;
}

static inline unsigned int __attribute__((always_inline))
rte_ring_mp_enqueue_bulk(struct rte_ring *r, void * const *obj_table,
                         unsigned int n, unsigned int *free_space)
{
        return __rte_ring_do_enqueue(r, obj_table, n, RTE_RING_QUEUE_FIXED,
                        __IS_MP, free_space);
}

static inline unsigned int __attribute__((always_inline))
rte_ring_sp_enqueue_bulk(struct rte_ring *r, void * const *obj_table,
                         unsigned int n, unsigned int *free_space)
{
        return __rte_ring_do_enqueue(r, obj_table, n, RTE_RING_QUEUE_FIXED,
                        __IS_SP, free_space);
}

static inline unsigned int __attribute__((always_inline))
rte_ring_enqueue_bulk(struct rte_ring *r, void * const *obj_table,
                      unsigned int n, unsigned int *free_space)
{
        return __rte_ring_do_enqueue(r, obj_table, n, RTE_RING_QUEUE_FIXED,
                        r->prod.single, free_space);
}

static inline int __attribute__((always_inline))
rte_ring_mp_enqueue(struct rte_ring *r, void *obj)
{
        return rte_ring_mp_enqueue_bulk(r, &obj, 1, NULL) ? 0 : -ENOBUFS;
}

static inline int __attribute__((always_inline))
rte_ring_sp_enqueue(struct rte_ring *r, void *obj)
{
        return rte_ring_sp_enqueue_bulk(r, &obj, 1, NULL) ? 0 : -ENOBUFS;
}

static inline int __attribute__((always_inline))
rte_ring_enqueue(struct rte_ring *r, void *obj)
{
        return rte_ring_enqueue_bulk(r, &obj, 1, NULL) ? 0 : -ENOBUFS;
}

static inline unsigned int __attribute__((always_inline))
rte_ring_mc_dequeue_bulk(struct rte_ring *r, void **obj_table,
                unsigned int n, unsigned int *available)
{
        return __rte_ring_do_dequeue(r, obj_table, n, RTE_RING_QUEUE_FIXED,
                        __IS_MC, available);
}

static inline unsigned int __attribute__((always_inline))
rte_ring_sc_dequeue_bulk(struct rte_ring *r, void **obj_table,
                unsigned int n, unsigned int *available)
{
        return __rte_ring_do_dequeue(r, obj_table, n, RTE_RING_QUEUE_FIXED,
                        __IS_SC, available);
}

static inline unsigned int __attribute__((always_inline))
rte_ring_dequeue_bulk(struct rte_ring *r, void **obj_table, unsigned int n,
                unsigned int *available)
{
        return __rte_ring_do_dequeue(r, obj_table, n, RTE_RING_QUEUE_FIXED,
                                r->cons.single, available);
}

static inline int __attribute__((always_inline))
rte_ring_mc_dequeue(struct rte_ring *r, void **obj_p)
{
        return rte_ring_mc_dequeue_bulk(r, obj_p, 1, NULL)  ? 0 : -ENOENT;
}

static inline int __attribute__((always_inline))
rte_ring_sc_dequeue(struct rte_ring *r, void **obj_p)
{
        return rte_ring_sc_dequeue_bulk(r, obj_p, 1, NULL) ? 0 : -ENOENT;
}

static inline int __attribute__((always_inline))
rte_ring_dequeue(struct rte_ring *r, void **obj_p)
{
        return rte_ring_dequeue_bulk(r, obj_p, 1, NULL) ? 0 : -ENOENT;
}

static inline int
rte_ring_full(const struct rte_ring *r)
{
        uint32_t prod_tail = r->prod.tail;
        uint32_t cons_tail = r->cons.tail;
        return ((cons_tail - prod_tail - 1) & r->mask) == 0;
}

static inline int
rte_ring_empty(const struct rte_ring *r)
{
        uint32_t prod_tail = r->prod.tail;
        uint32_t cons_tail = r->cons.tail;
        return !!(cons_tail == prod_tail);
}

static inline unsigned
rte_ring_count(const struct rte_ring *r)
{
        uint32_t prod_tail = r->prod.tail;
        uint32_t cons_tail = r->cons.tail;
        return (prod_tail - cons_tail) & r->mask;
}

static inline unsigned
rte_ring_free_count(const struct rte_ring *r)
{
        uint32_t prod_tail = r->prod.tail;
        uint32_t cons_tail = r->cons.tail;
        return (cons_tail - prod_tail - 1) & r->mask;
}

static inline unsigned int
rte_ring_get_size(const struct rte_ring *r)
{
        return r->size;
}

void rte_ring_list_dump(FILE *f);

struct rte_ring *rte_ring_lookup(const char *name);

static inline unsigned __attribute__((always_inline))
rte_ring_mp_enqueue_burst(struct rte_ring *r, void * const *obj_table,
                         unsigned int n, unsigned int *free_space)
{
        return __rte_ring_do_enqueue(r, obj_table, n,
                        RTE_RING_QUEUE_VARIABLE, __IS_MP, free_space);
}

static inline unsigned __attribute__((always_inline))
rte_ring_sp_enqueue_burst(struct rte_ring *r, void * const *obj_table,
                         unsigned int n, unsigned int *free_space)
{
        return __rte_ring_do_enqueue(r, obj_table, n,
                        RTE_RING_QUEUE_VARIABLE, __IS_SP, free_space);
}

static inline unsigned __attribute__((always_inline))
rte_ring_enqueue_burst(struct rte_ring *r, void * const *obj_table,
                      unsigned int n, unsigned int *free_space)
{
        return __rte_ring_do_enqueue(r, obj_table, n, RTE_RING_QUEUE_VARIABLE,
                        r->prod.single, free_space);
}

static inline unsigned __attribute__((always_inline))
rte_ring_mc_dequeue_burst(struct rte_ring *r, void **obj_table,
                unsigned int n, unsigned int *available)
{
        return __rte_ring_do_dequeue(r, obj_table, n,
                        RTE_RING_QUEUE_VARIABLE, __IS_MC, available);
}

static inline unsigned __attribute__((always_inline))
rte_ring_sc_dequeue_burst(struct rte_ring *r, void **obj_table,
                unsigned int n, unsigned int *available)
{
        return __rte_ring_do_dequeue(r, obj_table, n,
                        RTE_RING_QUEUE_VARIABLE, __IS_SC, available);
}

static inline unsigned __attribute__((always_inline))
rte_ring_dequeue_burst(struct rte_ring *r, void **obj_table,
                unsigned int n, unsigned int *available)
{
        return __rte_ring_do_dequeue(r, obj_table, n,
                                RTE_RING_QUEUE_VARIABLE,
                                r->cons.single, available);
}

#ifdef __cplusplus
}
#endif

#endif /* _RTE_RING_H_ */