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35 * Derived from FreeBSD's bufring.h
37 **************************************************************************
39 * Copyright (c) 2007-2009 Kip Macy kmacy@freebsd.org
40 * All rights reserved.
42 * Redistribution and use in source and binary forms, with or without
43 * modification, are permitted provided that the following conditions are met:
45 * 1. Redistributions of source code must retain the above copyright notice,
46 * this list of conditions and the following disclaimer.
48 * 2. The name of Kip Macy nor the names of other
49 * contributors may be used to endorse or promote products derived from
50 * this software without specific prior written permission.
52 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
53 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
54 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
55 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
56 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
57 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
58 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
59 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
60 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
61 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
62 * POSSIBILITY OF SUCH DAMAGE.
64 ***************************************************************************/
73 * The Ring Manager is a fixed-size queue, implemented as a table of
74 * pointers. Head and tail pointers are modified atomically, allowing
75 * concurrent access to it. It has the following features:
77 * - FIFO (First In First Out)
78 * - Maximum size is fixed; the pointers are stored in a table.
79 * - Lockless implementation.
80 * - Multi- or single-consumer dequeue.
81 * - Multi- or single-producer enqueue.
85 * Note: the ring implementation is not preemptable. A lcore must not
86 * be interrupted by another task that uses the same ring.
96 #include <sys/queue.h>
98 #include <rte_common.h>
99 #include <rte_config.h>
100 #include <rte_memory.h>
101 #include <rte_lcore.h>
102 #include <rte_atomic.h>
103 #include <rte_branch_prediction.h>
104 #include <rte_memzone.h>
105 #include <rte_pause.h>
107 #define RTE_TAILQ_RING_NAME "RTE_RING"
109 enum rte_ring_queue_behavior {
110 RTE_RING_QUEUE_FIXED = 0, /* Enq/Deq a fixed number of items from a ring */
111 RTE_RING_QUEUE_VARIABLE /* Enq/Deq as many items as possible from ring */
114 #define RTE_RING_MZ_PREFIX "RG_"
115 /**< The maximum length of a ring name. */
116 #define RTE_RING_NAMESIZE (RTE_MEMZONE_NAMESIZE - \
117 sizeof(RTE_RING_MZ_PREFIX) + 1)
119 struct rte_memzone; /* forward declaration, so as not to require memzone.h */
121 #if RTE_CACHE_LINE_SIZE < 128
122 #define PROD_ALIGN (RTE_CACHE_LINE_SIZE * 2)
123 #define CONS_ALIGN (RTE_CACHE_LINE_SIZE * 2)
125 #define PROD_ALIGN RTE_CACHE_LINE_SIZE
126 #define CONS_ALIGN RTE_CACHE_LINE_SIZE
129 /* structure to hold a pair of head/tail values and other metadata */
130 struct rte_ring_headtail {
131 volatile uint32_t head; /**< Prod/consumer head. */
132 volatile uint32_t tail; /**< Prod/consumer tail. */
133 uint32_t single; /**< True if single prod/cons */
137 * An RTE ring structure.
139 * The producer and the consumer have a head and a tail index. The particularity
140 * of these index is that they are not between 0 and size(ring). These indexes
141 * are between 0 and 2^32, and we mask their value when we access the ring[]
142 * field. Thanks to this assumption, we can do subtractions between 2 index
143 * values in a modulo-32bit base: that's why the overflow of the indexes is not
148 * Note: this field kept the RTE_MEMZONE_NAMESIZE size due to ABI
149 * compatibility requirements, it could be changed to RTE_RING_NAMESIZE
150 * next time the ABI changes
152 char name[RTE_MEMZONE_NAMESIZE] __rte_cache_aligned; /**< Name of the ring. */
153 int flags; /**< Flags supplied at creation. */
154 const struct rte_memzone *memzone;
155 /**< Memzone, if any, containing the rte_ring */
156 uint32_t size; /**< Size of ring. */
157 uint32_t mask; /**< Mask (size-1) of ring. */
158 uint32_t capacity; /**< Usable size of ring */
160 /** Ring producer status. */
161 struct rte_ring_headtail prod __rte_aligned(PROD_ALIGN);
163 /** Ring consumer status. */
164 struct rte_ring_headtail cons __rte_aligned(CONS_ALIGN);
167 #define RING_F_SP_ENQ 0x0001 /**< The default enqueue is "single-producer". */
168 #define RING_F_SC_DEQ 0x0002 /**< The default dequeue is "single-consumer". */
170 * Ring is to hold exactly requested number of entries.
171 * Without this flag set, the ring size requested must be a power of 2, and the
172 * usable space will be that size - 1. With the flag, the requested size will
173 * be rounded up to the next power of two, but the usable space will be exactly
174 * that requested. Worst case, if a power-of-2 size is requested, half the
175 * ring space will be wasted.
177 #define RING_F_EXACT_SZ 0x0004
178 #define RTE_RING_SZ_MASK (0x7fffffffU) /**< Ring size mask */
180 /* @internal defines for passing to the enqueue dequeue worker functions */
187 * Calculate the memory size needed for a ring
189 * This function returns the number of bytes needed for a ring, given
190 * the number of elements in it. This value is the sum of the size of
191 * the structure rte_ring and the size of the memory needed by the
192 * objects pointers. The value is aligned to a cache line size.
195 * The number of elements in the ring (must be a power of 2).
197 * - The memory size needed for the ring on success.
198 * - -EINVAL if count is not a power of 2.
200 ssize_t rte_ring_get_memsize(unsigned count);
203 * Initialize a ring structure.
205 * Initialize a ring structure in memory pointed by "r". The size of the
206 * memory area must be large enough to store the ring structure and the
207 * object table. It is advised to use rte_ring_get_memsize() to get the
210 * The ring size is set to *count*, which must be a power of two. Water
211 * marking is disabled by default. The real usable ring size is
212 * *count-1* instead of *count* to differentiate a free ring from an
215 * The ring is not added in RTE_TAILQ_RING global list. Indeed, the
216 * memory given by the caller may not be shareable among dpdk
220 * The pointer to the ring structure followed by the objects table.
222 * The name of the ring.
224 * The number of elements in the ring (must be a power of 2).
226 * An OR of the following:
227 * - RING_F_SP_ENQ: If this flag is set, the default behavior when
228 * using ``rte_ring_enqueue()`` or ``rte_ring_enqueue_bulk()``
229 * is "single-producer". Otherwise, it is "multi-producers".
230 * - RING_F_SC_DEQ: If this flag is set, the default behavior when
231 * using ``rte_ring_dequeue()`` or ``rte_ring_dequeue_bulk()``
232 * is "single-consumer". Otherwise, it is "multi-consumers".
234 * 0 on success, or a negative value on error.
236 int rte_ring_init(struct rte_ring *r, const char *name, unsigned count,
240 * Create a new ring named *name* in memory.
242 * This function uses ``memzone_reserve()`` to allocate memory. Then it
243 * calls rte_ring_init() to initialize an empty ring.
245 * The new ring size is set to *count*, which must be a power of
246 * two. Water marking is disabled by default. The real usable ring size
247 * is *count-1* instead of *count* to differentiate a free ring from an
250 * The ring is added in RTE_TAILQ_RING list.
253 * The name of the ring.
255 * The size of the ring (must be a power of 2).
257 * The *socket_id* argument is the socket identifier in case of
258 * NUMA. The value can be *SOCKET_ID_ANY* if there is no NUMA
259 * constraint for the reserved zone.
261 * An OR of the following:
262 * - RING_F_SP_ENQ: If this flag is set, the default behavior when
263 * using ``rte_ring_enqueue()`` or ``rte_ring_enqueue_bulk()``
264 * is "single-producer". Otherwise, it is "multi-producers".
265 * - RING_F_SC_DEQ: If this flag is set, the default behavior when
266 * using ``rte_ring_dequeue()`` or ``rte_ring_dequeue_bulk()``
267 * is "single-consumer". Otherwise, it is "multi-consumers".
269 * On success, the pointer to the new allocated ring. NULL on error with
270 * rte_errno set appropriately. Possible errno values include:
271 * - E_RTE_NO_CONFIG - function could not get pointer to rte_config structure
272 * - E_RTE_SECONDARY - function was called from a secondary process instance
273 * - EINVAL - count provided is not a power of 2
274 * - ENOSPC - the maximum number of memzones has already been allocated
275 * - EEXIST - a memzone with the same name already exists
276 * - ENOMEM - no appropriate memory area found in which to create memzone
278 struct rte_ring *rte_ring_create(const char *name, unsigned count,
279 int socket_id, unsigned flags);
281 * De-allocate all memory used by the ring.
286 void rte_ring_free(struct rte_ring *r);
289 * Dump the status of the ring to a file.
292 * A pointer to a file for output
294 * A pointer to the ring structure.
296 void rte_ring_dump(FILE *f, const struct rte_ring *r);
298 /* the actual enqueue of pointers on the ring.
299 * Placed here since identical code needed in both
300 * single and multi producer enqueue functions */
301 #define ENQUEUE_PTRS(r, ring_start, prod_head, obj_table, n, obj_type) do { \
303 const uint32_t size = (r)->size; \
304 uint32_t idx = prod_head & (r)->mask; \
305 obj_type *ring = (obj_type *)ring_start; \
306 if (likely(idx + n < size)) { \
307 for (i = 0; i < (n & ((~(unsigned)0x3))); i+=4, idx+=4) { \
308 ring[idx] = obj_table[i]; \
309 ring[idx+1] = obj_table[i+1]; \
310 ring[idx+2] = obj_table[i+2]; \
311 ring[idx+3] = obj_table[i+3]; \
315 ring[idx++] = obj_table[i++]; /* fallthrough */ \
317 ring[idx++] = obj_table[i++]; /* fallthrough */ \
319 ring[idx++] = obj_table[i++]; \
322 for (i = 0; idx < size; i++, idx++)\
323 ring[idx] = obj_table[i]; \
324 for (idx = 0; i < n; i++, idx++) \
325 ring[idx] = obj_table[i]; \
329 /* the actual copy of pointers on the ring to obj_table.
330 * Placed here since identical code needed in both
331 * single and multi consumer dequeue functions */
332 #define DEQUEUE_PTRS(r, ring_start, cons_head, obj_table, n, obj_type) do { \
334 uint32_t idx = cons_head & (r)->mask; \
335 const uint32_t size = (r)->size; \
336 obj_type *ring = (obj_type *)ring_start; \
337 if (likely(idx + n < size)) { \
338 for (i = 0; i < (n & (~(unsigned)0x3)); i+=4, idx+=4) {\
339 obj_table[i] = ring[idx]; \
340 obj_table[i+1] = ring[idx+1]; \
341 obj_table[i+2] = ring[idx+2]; \
342 obj_table[i+3] = ring[idx+3]; \
346 obj_table[i++] = ring[idx++]; /* fallthrough */ \
348 obj_table[i++] = ring[idx++]; /* fallthrough */ \
350 obj_table[i++] = ring[idx++]; \
353 for (i = 0; idx < size; i++, idx++) \
354 obj_table[i] = ring[idx]; \
355 for (idx = 0; i < n; i++, idx++) \
356 obj_table[i] = ring[idx]; \
360 static __rte_always_inline void
361 update_tail(struct rte_ring_headtail *ht, uint32_t old_val, uint32_t new_val,
365 * If there are other enqueues/dequeues in progress that preceded us,
366 * we need to wait for them to complete
369 while (unlikely(ht->tail != old_val))
376 * @internal This function updates the producer head for enqueue
379 * A pointer to the ring structure
381 * Indicates whether multi-producer path is needed or not
383 * The number of elements we will want to enqueue, i.e. how far should the
386 * RTE_RING_QUEUE_FIXED: Enqueue a fixed number of items from a ring
387 * RTE_RING_QUEUE_VARIABLE: Enqueue as many items as possible from ring
389 * Returns head value as it was before the move, i.e. where enqueue starts
391 * Returns the current/new head value i.e. where enqueue finishes
392 * @param free_entries
393 * Returns the amount of free space in the ring BEFORE head was moved
395 * Actual number of objects enqueued.
396 * If behavior == RTE_RING_QUEUE_FIXED, this will be 0 or n only.
398 static __rte_always_inline unsigned int
399 __rte_ring_move_prod_head(struct rte_ring *r, unsigned int is_sp,
400 unsigned int n, enum rte_ring_queue_behavior behavior,
401 uint32_t *old_head, uint32_t *new_head,
402 uint32_t *free_entries)
404 const uint32_t capacity = r->capacity;
405 unsigned int max = n;
409 /* Reset n to the initial burst count */
412 *old_head = r->prod.head;
414 /* add rmb barrier to avoid load/load reorder in weak
415 * memory model. It is noop on x86
420 * The subtraction is done between two unsigned 32bits value
421 * (the result is always modulo 32 bits even if we have
422 * *old_head > cons_tail). So 'free_entries' is always between 0
423 * and capacity (which is < size).
425 *free_entries = (capacity + r->cons.tail - *old_head);
427 /* check that we have enough room in ring */
428 if (unlikely(n > *free_entries))
429 n = (behavior == RTE_RING_QUEUE_FIXED) ?
435 *new_head = *old_head + n;
437 r->prod.head = *new_head, success = 1;
439 success = rte_atomic32_cmpset(&r->prod.head,
440 *old_head, *new_head);
441 } while (unlikely(success == 0));
446 * @internal Enqueue several objects on the ring
449 * A pointer to the ring structure.
451 * A pointer to a table of void * pointers (objects).
453 * The number of objects to add in the ring from the obj_table.
455 * RTE_RING_QUEUE_FIXED: Enqueue a fixed number of items from a ring
456 * RTE_RING_QUEUE_VARIABLE: Enqueue as many items as possible from ring
458 * Indicates whether to use single producer or multi-producer head update
460 * returns the amount of space after the enqueue operation has finished
462 * Actual number of objects enqueued.
463 * If behavior == RTE_RING_QUEUE_FIXED, this will be 0 or n only.
465 static __rte_always_inline unsigned int
466 __rte_ring_do_enqueue(struct rte_ring *r, void * const *obj_table,
467 unsigned int n, enum rte_ring_queue_behavior behavior,
468 unsigned int is_sp, unsigned int *free_space)
470 uint32_t prod_head, prod_next;
471 uint32_t free_entries;
473 n = __rte_ring_move_prod_head(r, is_sp, n, behavior,
474 &prod_head, &prod_next, &free_entries);
478 ENQUEUE_PTRS(r, &r[1], prod_head, obj_table, n, void *);
481 update_tail(&r->prod, prod_head, prod_next, is_sp);
483 if (free_space != NULL)
484 *free_space = free_entries - n;
489 * @internal This function updates the consumer head for dequeue
492 * A pointer to the ring structure
494 * Indicates whether multi-consumer path is needed or not
496 * The number of elements we will want to enqueue, i.e. how far should the
499 * RTE_RING_QUEUE_FIXED: Dequeue a fixed number of items from a ring
500 * RTE_RING_QUEUE_VARIABLE: Dequeue as many items as possible from ring
502 * Returns head value as it was before the move, i.e. where dequeue starts
504 * Returns the current/new head value i.e. where dequeue finishes
506 * Returns the number of entries in the ring BEFORE head was moved
508 * - Actual number of objects dequeued.
509 * If behavior == RTE_RING_QUEUE_FIXED, this will be 0 or n only.
511 static __rte_always_inline unsigned int
512 __rte_ring_move_cons_head(struct rte_ring *r, unsigned int is_sc,
513 unsigned int n, enum rte_ring_queue_behavior behavior,
514 uint32_t *old_head, uint32_t *new_head,
517 unsigned int max = n;
520 /* move cons.head atomically */
522 /* Restore n as it may change every loop */
525 *old_head = r->cons.head;
527 /* add rmb barrier to avoid load/load reorder in weak
528 * memory model. It is noop on x86
532 /* The subtraction is done between two unsigned 32bits value
533 * (the result is always modulo 32 bits even if we have
534 * cons_head > prod_tail). So 'entries' is always between 0
535 * and size(ring)-1. */
536 *entries = (r->prod.tail - *old_head);
538 /* Set the actual entries for dequeue */
540 n = (behavior == RTE_RING_QUEUE_FIXED) ? 0 : *entries;
542 if (unlikely(n == 0))
545 *new_head = *old_head + n;
547 r->cons.head = *new_head, success = 1;
549 success = rte_atomic32_cmpset(&r->cons.head, *old_head,
551 } while (unlikely(success == 0));
556 * @internal Dequeue several objects from the ring
559 * A pointer to the ring structure.
561 * A pointer to a table of void * pointers (objects).
563 * The number of objects to pull from the ring.
565 * RTE_RING_QUEUE_FIXED: Dequeue a fixed number of items from a ring
566 * RTE_RING_QUEUE_VARIABLE: Dequeue as many items as possible from ring
568 * Indicates whether to use single consumer or multi-consumer head update
570 * returns the number of remaining ring entries after the dequeue has finished
572 * - Actual number of objects dequeued.
573 * If behavior == RTE_RING_QUEUE_FIXED, this will be 0 or n only.
575 static __rte_always_inline unsigned int
576 __rte_ring_do_dequeue(struct rte_ring *r, void **obj_table,
577 unsigned int n, enum rte_ring_queue_behavior behavior,
578 unsigned int is_sc, unsigned int *available)
580 uint32_t cons_head, cons_next;
583 n = __rte_ring_move_cons_head(r, (int)is_sc, n, behavior,
584 &cons_head, &cons_next, &entries);
588 DEQUEUE_PTRS(r, &r[1], cons_head, obj_table, n, void *);
591 update_tail(&r->cons, cons_head, cons_next, is_sc);
594 if (available != NULL)
595 *available = entries - n;
600 * Enqueue several objects on the ring (multi-producers safe).
602 * This function uses a "compare and set" instruction to move the
603 * producer index atomically.
606 * A pointer to the ring structure.
608 * A pointer to a table of void * pointers (objects).
610 * The number of objects to add in the ring from the obj_table.
612 * if non-NULL, returns the amount of space in the ring after the
613 * enqueue operation has finished.
615 * The number of objects enqueued, either 0 or n
617 static __rte_always_inline unsigned int
618 rte_ring_mp_enqueue_bulk(struct rte_ring *r, void * const *obj_table,
619 unsigned int n, unsigned int *free_space)
621 return __rte_ring_do_enqueue(r, obj_table, n, RTE_RING_QUEUE_FIXED,
622 __IS_MP, free_space);
626 * Enqueue several objects on a ring (NOT multi-producers safe).
629 * A pointer to the ring structure.
631 * A pointer to a table of void * pointers (objects).
633 * The number of objects to add in the ring from the obj_table.
635 * if non-NULL, returns the amount of space in the ring after the
636 * enqueue operation has finished.
638 * The number of objects enqueued, either 0 or n
640 static __rte_always_inline unsigned int
641 rte_ring_sp_enqueue_bulk(struct rte_ring *r, void * const *obj_table,
642 unsigned int n, unsigned int *free_space)
644 return __rte_ring_do_enqueue(r, obj_table, n, RTE_RING_QUEUE_FIXED,
645 __IS_SP, free_space);
649 * Enqueue several objects on a ring.
651 * This function calls the multi-producer or the single-producer
652 * version depending on the default behavior that was specified at
653 * ring creation time (see flags).
656 * A pointer to the ring structure.
658 * A pointer to a table of void * pointers (objects).
660 * The number of objects to add in the ring from the obj_table.
662 * if non-NULL, returns the amount of space in the ring after the
663 * enqueue operation has finished.
665 * The number of objects enqueued, either 0 or n
667 static __rte_always_inline unsigned int
668 rte_ring_enqueue_bulk(struct rte_ring *r, void * const *obj_table,
669 unsigned int n, unsigned int *free_space)
671 return __rte_ring_do_enqueue(r, obj_table, n, RTE_RING_QUEUE_FIXED,
672 r->prod.single, free_space);
676 * Enqueue one object on a ring (multi-producers safe).
678 * This function uses a "compare and set" instruction to move the
679 * producer index atomically.
682 * A pointer to the ring structure.
684 * A pointer to the object to be added.
686 * - 0: Success; objects enqueued.
687 * - -ENOBUFS: Not enough room in the ring to enqueue; no object is enqueued.
689 static __rte_always_inline int
690 rte_ring_mp_enqueue(struct rte_ring *r, void *obj)
692 return rte_ring_mp_enqueue_bulk(r, &obj, 1, NULL) ? 0 : -ENOBUFS;
696 * Enqueue one object on a ring (NOT multi-producers safe).
699 * A pointer to the ring structure.
701 * A pointer to the object to be added.
703 * - 0: Success; objects enqueued.
704 * - -ENOBUFS: Not enough room in the ring to enqueue; no object is enqueued.
706 static __rte_always_inline int
707 rte_ring_sp_enqueue(struct rte_ring *r, void *obj)
709 return rte_ring_sp_enqueue_bulk(r, &obj, 1, NULL) ? 0 : -ENOBUFS;
713 * Enqueue one object on a ring.
715 * This function calls the multi-producer or the single-producer
716 * version, depending on the default behaviour that was specified at
717 * ring creation time (see flags).
720 * A pointer to the ring structure.
722 * A pointer to the object to be added.
724 * - 0: Success; objects enqueued.
725 * - -ENOBUFS: Not enough room in the ring to enqueue; no object is enqueued.
727 static __rte_always_inline int
728 rte_ring_enqueue(struct rte_ring *r, void *obj)
730 return rte_ring_enqueue_bulk(r, &obj, 1, NULL) ? 0 : -ENOBUFS;
734 * Dequeue several objects from a ring (multi-consumers safe).
736 * This function uses a "compare and set" instruction to move the
737 * consumer index atomically.
740 * A pointer to the ring structure.
742 * A pointer to a table of void * pointers (objects) that will be filled.
744 * The number of objects to dequeue from the ring to the obj_table.
746 * If non-NULL, returns the number of remaining ring entries after the
747 * dequeue has finished.
749 * The number of objects dequeued, either 0 or n
751 static __rte_always_inline unsigned int
752 rte_ring_mc_dequeue_bulk(struct rte_ring *r, void **obj_table,
753 unsigned int n, unsigned int *available)
755 return __rte_ring_do_dequeue(r, obj_table, n, RTE_RING_QUEUE_FIXED,
760 * Dequeue several objects from a ring (NOT multi-consumers safe).
763 * A pointer to the ring structure.
765 * A pointer to a table of void * pointers (objects) that will be filled.
767 * The number of objects to dequeue from the ring to the obj_table,
768 * must be strictly positive.
770 * If non-NULL, returns the number of remaining ring entries after the
771 * dequeue has finished.
773 * The number of objects dequeued, either 0 or n
775 static __rte_always_inline unsigned int
776 rte_ring_sc_dequeue_bulk(struct rte_ring *r, void **obj_table,
777 unsigned int n, unsigned int *available)
779 return __rte_ring_do_dequeue(r, obj_table, n, RTE_RING_QUEUE_FIXED,
784 * Dequeue several objects from a ring.
786 * This function calls the multi-consumers or the single-consumer
787 * version, depending on the default behaviour that was specified at
788 * ring creation time (see flags).
791 * A pointer to the ring structure.
793 * A pointer to a table of void * pointers (objects) that will be filled.
795 * The number of objects to dequeue from the ring to the obj_table.
797 * If non-NULL, returns the number of remaining ring entries after the
798 * dequeue has finished.
800 * The number of objects dequeued, either 0 or n
802 static __rte_always_inline unsigned int
803 rte_ring_dequeue_bulk(struct rte_ring *r, void **obj_table, unsigned int n,
804 unsigned int *available)
806 return __rte_ring_do_dequeue(r, obj_table, n, RTE_RING_QUEUE_FIXED,
807 r->cons.single, available);
811 * Dequeue one object from a ring (multi-consumers safe).
813 * This function uses a "compare and set" instruction to move the
814 * consumer index atomically.
817 * A pointer to the ring structure.
819 * A pointer to a void * pointer (object) that will be filled.
821 * - 0: Success; objects dequeued.
822 * - -ENOENT: Not enough entries in the ring to dequeue; no object is
825 static __rte_always_inline int
826 rte_ring_mc_dequeue(struct rte_ring *r, void **obj_p)
828 return rte_ring_mc_dequeue_bulk(r, obj_p, 1, NULL) ? 0 : -ENOENT;
832 * Dequeue one object from a ring (NOT multi-consumers safe).
835 * A pointer to the ring structure.
837 * A pointer to a void * pointer (object) that will be filled.
839 * - 0: Success; objects dequeued.
840 * - -ENOENT: Not enough entries in the ring to dequeue, no object is
843 static __rte_always_inline int
844 rte_ring_sc_dequeue(struct rte_ring *r, void **obj_p)
846 return rte_ring_sc_dequeue_bulk(r, obj_p, 1, NULL) ? 0 : -ENOENT;
850 * Dequeue one object from a ring.
852 * This function calls the multi-consumers or the single-consumer
853 * version depending on the default behaviour that was specified at
854 * ring creation time (see flags).
857 * A pointer to the ring structure.
859 * A pointer to a void * pointer (object) that will be filled.
861 * - 0: Success, objects dequeued.
862 * - -ENOENT: Not enough entries in the ring to dequeue, no object is
865 static __rte_always_inline int
866 rte_ring_dequeue(struct rte_ring *r, void **obj_p)
868 return rte_ring_dequeue_bulk(r, obj_p, 1, NULL) ? 0 : -ENOENT;
872 * Return the number of entries in a ring.
875 * A pointer to the ring structure.
877 * The number of entries in the ring.
879 static inline unsigned
880 rte_ring_count(const struct rte_ring *r)
882 uint32_t prod_tail = r->prod.tail;
883 uint32_t cons_tail = r->cons.tail;
884 uint32_t count = (prod_tail - cons_tail) & r->mask;
885 return (count > r->capacity) ? r->capacity : count;
889 * Return the number of free entries in a ring.
892 * A pointer to the ring structure.
894 * The number of free entries in the ring.
896 static inline unsigned
897 rte_ring_free_count(const struct rte_ring *r)
899 return r->capacity - rte_ring_count(r);
903 * Test if a ring is full.
906 * A pointer to the ring structure.
908 * - 1: The ring is full.
909 * - 0: The ring is not full.
912 rte_ring_full(const struct rte_ring *r)
914 return rte_ring_free_count(r) == 0;
918 * Test if a ring is empty.
921 * A pointer to the ring structure.
923 * - 1: The ring is empty.
924 * - 0: The ring is not empty.
927 rte_ring_empty(const struct rte_ring *r)
929 return rte_ring_count(r) == 0;
933 * Return the size of the ring.
936 * A pointer to the ring structure.
938 * The size of the data store used by the ring.
939 * NOTE: this is not the same as the usable space in the ring. To query that
940 * use ``rte_ring_get_capacity()``.
942 static inline unsigned int
943 rte_ring_get_size(const struct rte_ring *r)
949 * Return the number of elements which can be stored in the ring.
952 * A pointer to the ring structure.
954 * The usable size of the ring.
956 static inline unsigned int
957 rte_ring_get_capacity(const struct rte_ring *r)
963 * Dump the status of all rings on the console
966 * A pointer to a file for output
968 void rte_ring_list_dump(FILE *f);
971 * Search a ring from its name
974 * The name of the ring.
976 * The pointer to the ring matching the name, or NULL if not found,
977 * with rte_errno set appropriately. Possible rte_errno values include:
978 * - ENOENT - required entry not available to return.
980 struct rte_ring *rte_ring_lookup(const char *name);
983 * Enqueue several objects on the ring (multi-producers safe).
985 * This function uses a "compare and set" instruction to move the
986 * producer index atomically.
989 * A pointer to the ring structure.
991 * A pointer to a table of void * pointers (objects).
993 * The number of objects to add in the ring from the obj_table.
995 * if non-NULL, returns the amount of space in the ring after the
996 * enqueue operation has finished.
998 * - n: Actual number of objects enqueued.
1000 static __rte_always_inline unsigned
1001 rte_ring_mp_enqueue_burst(struct rte_ring *r, void * const *obj_table,
1002 unsigned int n, unsigned int *free_space)
1004 return __rte_ring_do_enqueue(r, obj_table, n,
1005 RTE_RING_QUEUE_VARIABLE, __IS_MP, free_space);
1009 * Enqueue several objects on a ring (NOT multi-producers safe).
1012 * A pointer to the ring structure.
1014 * A pointer to a table of void * pointers (objects).
1016 * The number of objects to add in the ring from the obj_table.
1018 * if non-NULL, returns the amount of space in the ring after the
1019 * enqueue operation has finished.
1021 * - n: Actual number of objects enqueued.
1023 static __rte_always_inline unsigned
1024 rte_ring_sp_enqueue_burst(struct rte_ring *r, void * const *obj_table,
1025 unsigned int n, unsigned int *free_space)
1027 return __rte_ring_do_enqueue(r, obj_table, n,
1028 RTE_RING_QUEUE_VARIABLE, __IS_SP, free_space);
1032 * Enqueue several objects on a ring.
1034 * This function calls the multi-producer or the single-producer
1035 * version depending on the default behavior that was specified at
1036 * ring creation time (see flags).
1039 * A pointer to the ring structure.
1041 * A pointer to a table of void * pointers (objects).
1043 * The number of objects to add in the ring from the obj_table.
1045 * if non-NULL, returns the amount of space in the ring after the
1046 * enqueue operation has finished.
1048 * - n: Actual number of objects enqueued.
1050 static __rte_always_inline unsigned
1051 rte_ring_enqueue_burst(struct rte_ring *r, void * const *obj_table,
1052 unsigned int n, unsigned int *free_space)
1054 return __rte_ring_do_enqueue(r, obj_table, n, RTE_RING_QUEUE_VARIABLE,
1055 r->prod.single, free_space);
1059 * Dequeue several objects from a ring (multi-consumers safe). When the request
1060 * objects are more than the available objects, only dequeue the actual number
1063 * This function uses a "compare and set" instruction to move the
1064 * consumer index atomically.
1067 * A pointer to the ring structure.
1069 * A pointer to a table of void * pointers (objects) that will be filled.
1071 * The number of objects to dequeue from the ring to the obj_table.
1073 * If non-NULL, returns the number of remaining ring entries after the
1074 * dequeue has finished.
1076 * - n: Actual number of objects dequeued, 0 if ring is empty
1078 static __rte_always_inline unsigned
1079 rte_ring_mc_dequeue_burst(struct rte_ring *r, void **obj_table,
1080 unsigned int n, unsigned int *available)
1082 return __rte_ring_do_dequeue(r, obj_table, n,
1083 RTE_RING_QUEUE_VARIABLE, __IS_MC, available);
1087 * Dequeue several objects from a ring (NOT multi-consumers safe).When the
1088 * request objects are more than the available objects, only dequeue the
1089 * actual number of objects
1092 * A pointer to the ring structure.
1094 * A pointer to a table of void * pointers (objects) that will be filled.
1096 * The number of objects to dequeue from the ring to the obj_table.
1098 * If non-NULL, returns the number of remaining ring entries after the
1099 * dequeue has finished.
1101 * - n: Actual number of objects dequeued, 0 if ring is empty
1103 static __rte_always_inline unsigned
1104 rte_ring_sc_dequeue_burst(struct rte_ring *r, void **obj_table,
1105 unsigned int n, unsigned int *available)
1107 return __rte_ring_do_dequeue(r, obj_table, n,
1108 RTE_RING_QUEUE_VARIABLE, __IS_SC, available);
1112 * Dequeue multiple objects from a ring up to a maximum number.
1114 * This function calls the multi-consumers or the single-consumer
1115 * version, depending on the default behaviour that was specified at
1116 * ring creation time (see flags).
1119 * A pointer to the ring structure.
1121 * A pointer to a table of void * pointers (objects) that will be filled.
1123 * The number of objects to dequeue from the ring to the obj_table.
1125 * If non-NULL, returns the number of remaining ring entries after the
1126 * dequeue has finished.
1128 * - Number of objects dequeued
1130 static __rte_always_inline unsigned
1131 rte_ring_dequeue_burst(struct rte_ring *r, void **obj_table,
1132 unsigned int n, unsigned int *available)
1134 return __rte_ring_do_dequeue(r, obj_table, n,
1135 RTE_RING_QUEUE_VARIABLE,
1136 r->cons.single, available);
1143 #endif /* _RTE_RING_H_ */