ceph/src/seastar/dpdk/lib/librte_ring/rte_ring.h

   1 /* SPDX-License-Identifier: BSD-3-Clause
   2  *
   3  * Copyright (c) 2010-2017 Intel Corporation
   4  * Copyright (c) 2007-2009 Kip Macy kmacy@freebsd.org
   5  * All rights reserved.
   6  * Derived from FreeBSD's bufring.h
   7  * Used as BSD-3 Licensed with permission from Kip Macy.
   8  */
   9
  10 #ifndef _RTE_RING_H_
  11 #define _RTE_RING_H_
  12
  13 /**
  14  * @file
  15  * RTE Ring
  16  *
  17  * The Ring Manager is a fixed-size queue, implemented as a table of
  18  * pointers. Head and tail pointers are modified atomically, allowing
  19  * concurrent access to it. It has the following features:
  20  *
  21  * - FIFO (First In First Out)
  22  * - Maximum size is fixed; the pointers are stored in a table.
  23  * - Lockless implementation.
  24  * - Multi- or single-consumer dequeue.
  25  * - Multi- or single-producer enqueue.
  26  * - Bulk dequeue.
  27  * - Bulk enqueue.
  28  *
  29  * Note: the ring implementation is not preemptible. Refer to Programmer's
  30  * guide/Environment Abstraction Layer/Multiple pthread/Known Issues/rte_ring
  31  * for more information.
  32  *
  33  */
  34
  35 #ifdef __cplusplus
  36 extern "C" {
  37 #endif
  38
  39 #include <stdio.h>
  40 #include <stdint.h>
  41 #include <sys/queue.h>
  42 #include <errno.h>
  43 #include <rte_common.h>
  44 #include <rte_config.h>
  45 #include <rte_memory.h>
  46 #include <rte_lcore.h>
  47 #include <rte_atomic.h>
  48 #include <rte_branch_prediction.h>
  49 #include <rte_memzone.h>
  50 #include <rte_pause.h>
  51
  52 #define RTE_TAILQ_RING_NAME "RTE_RING"
  53
  54 enum rte_ring_queue_behavior {
  55         RTE_RING_QUEUE_FIXED = 0, /* Enq/Deq a fixed number of items from a ring */
  56         RTE_RING_QUEUE_VARIABLE   /* Enq/Deq as many items as possible from ring */
  57 };
  58
  59 #define RTE_RING_MZ_PREFIX "RG_"
  60 /** The maximum length of a ring name. */
  61 #define RTE_RING_NAMESIZE (RTE_MEMZONE_NAMESIZE - \
  62                            sizeof(RTE_RING_MZ_PREFIX) + 1)
  63
  64 struct rte_memzone; /* forward declaration, so as not to require memzone.h */
  65
  66 /* structure to hold a pair of head/tail values and other metadata */
  67 struct rte_ring_headtail {
  68         volatile uint32_t head;  /**< Prod/consumer head. */
  69         volatile uint32_t tail;  /**< Prod/consumer tail. */
  70         uint32_t single;         /**< True if single prod/cons */
  71 };
  72
  73 /**
  74  * An RTE ring structure.
  75  *
  76  * The producer and the consumer have a head and a tail index. The particularity
  77  * of these index is that they are not between 0 and size(ring). These indexes
  78  * are between 0 and 2^32, and we mask their value when we access the ring[]
  79  * field. Thanks to this assumption, we can do subtractions between 2 index
  80  * values in a modulo-32bit base: that's why the overflow of the indexes is not
  81  * a problem.
  82  */
  83 struct rte_ring {
  84         /*
  85          * Note: this field kept the RTE_MEMZONE_NAMESIZE size due to ABI
  86          * compatibility requirements, it could be changed to RTE_RING_NAMESIZE
  87          * next time the ABI changes
  88          */
  89         char name[RTE_MEMZONE_NAMESIZE] __rte_cache_aligned; /**< Name of the ring. */
  90         int flags;               /**< Flags supplied at creation. */
  91         const struct rte_memzone *memzone;
  92                         /**< Memzone, if any, containing the rte_ring */
  93         uint32_t size;           /**< Size of ring. */
  94         uint32_t mask;           /**< Mask (size-1) of ring. */
  95         uint32_t capacity;       /**< Usable size of ring */
  96
  97         char pad0 __rte_cache_aligned; /**< empty cache line */
  98
  99         /** Ring producer status. */
 100         struct rte_ring_headtail prod __rte_cache_aligned;
 101         char pad1 __rte_cache_aligned; /**< empty cache line */
 102
 103         /** Ring consumer status. */
 104         struct rte_ring_headtail cons __rte_cache_aligned;
 105         char pad2 __rte_cache_aligned; /**< empty cache line */
 106 };
 107
 108 #define RING_F_SP_ENQ 0x0001 /**< The default enqueue is "single-producer". */
 109 #define RING_F_SC_DEQ 0x0002 /**< The default dequeue is "single-consumer". */
 110 /**
 111  * Ring is to hold exactly requested number of entries.
 112  * Without this flag set, the ring size requested must be a power of 2, and the
 113  * usable space will be that size - 1. With the flag, the requested size will
 114  * be rounded up to the next power of two, but the usable space will be exactly
 115  * that requested. Worst case, if a power-of-2 size is requested, half the
 116  * ring space will be wasted.
 117  */
 118 #define RING_F_EXACT_SZ 0x0004
 119 #define RTE_RING_SZ_MASK  (0x7fffffffU) /**< Ring size mask */
 120
 121 /* @internal defines for passing to the enqueue dequeue worker functions */
 122 #define __IS_SP 1
 123 #define __IS_MP 0
 124 #define __IS_SC 1
 125 #define __IS_MC 0
 126
 127 /**
 128  * Calculate the memory size needed for a ring
 129  *
 130  * This function returns the number of bytes needed for a ring, given
 131  * the number of elements in it. This value is the sum of the size of
 132  * the structure rte_ring and the size of the memory needed by the
 133  * objects pointers. The value is aligned to a cache line size.
 134  *
 135  * @param count
 136  *   The number of elements in the ring (must be a power of 2).
 137  * @return
 138  *   - The memory size needed for the ring on success.
 139  *   - -EINVAL if count is not a power of 2.
 140  */
 141 ssize_t rte_ring_get_memsize(unsigned count);
 142
 143 /**
 144  * Initialize a ring structure.
 145  *
 146  * Initialize a ring structure in memory pointed by "r". The size of the
 147  * memory area must be large enough to store the ring structure and the
 148  * object table. It is advised to use rte_ring_get_memsize() to get the
 149  * appropriate size.
 150  *
 151  * The ring size is set to *count*, which must be a power of two. Water
 152  * marking is disabled by default. The real usable ring size is
 153  * *count-1* instead of *count* to differentiate a free ring from an
 154  * empty ring.
 155  *
 156  * The ring is not added in RTE_TAILQ_RING global list. Indeed, the
 157  * memory given by the caller may not be shareable among dpdk
 158  * processes.
 159  *
 160  * @param r
 161  *   The pointer to the ring structure followed by the objects table.
 162  * @param name
 163  *   The name of the ring.
 164  * @param count
 165  *   The number of elements in the ring (must be a power of 2).
 166  * @param flags
 167  *   An OR of the following:
 168  *    - RING_F_SP_ENQ: If this flag is set, the default behavior when
 169  *      using ``rte_ring_enqueue()`` or ``rte_ring_enqueue_bulk()``
 170  *      is "single-producer". Otherwise, it is "multi-producers".
 171  *    - RING_F_SC_DEQ: If this flag is set, the default behavior when
 172  *      using ``rte_ring_dequeue()`` or ``rte_ring_dequeue_bulk()``
 173  *      is "single-consumer". Otherwise, it is "multi-consumers".
 174  * @return
 175  *   0 on success, or a negative value on error.
 176  */
 177 int rte_ring_init(struct rte_ring *r, const char *name, unsigned count,
 178         unsigned flags);
 179
 180 /**
 181  * Create a new ring named *name* in memory.
 182  *
 183  * This function uses ``memzone_reserve()`` to allocate memory. Then it
 184  * calls rte_ring_init() to initialize an empty ring.
 185  *
 186  * The new ring size is set to *count*, which must be a power of
 187  * two. Water marking is disabled by default. The real usable ring size
 188  * is *count-1* instead of *count* to differentiate a free ring from an
 189  * empty ring.
 190  *
 191  * The ring is added in RTE_TAILQ_RING list.
 192  *
 193  * @param name
 194  *   The name of the ring.
 195  * @param count
 196  *   The size of the ring (must be a power of 2).
 197  * @param socket_id
 198  *   The *socket_id* argument is the socket identifier in case of
 199  *   NUMA. The value can be *SOCKET_ID_ANY* if there is no NUMA
 200  *   constraint for the reserved zone.
 201  * @param flags
 202  *   An OR of the following:
 203  *    - RING_F_SP_ENQ: If this flag is set, the default behavior when
 204  *      using ``rte_ring_enqueue()`` or ``rte_ring_enqueue_bulk()``
 205  *      is "single-producer". Otherwise, it is "multi-producers".
 206  *    - RING_F_SC_DEQ: If this flag is set, the default behavior when
 207  *      using ``rte_ring_dequeue()`` or ``rte_ring_dequeue_bulk()``
 208  *      is "single-consumer". Otherwise, it is "multi-consumers".
 209  * @return
 210  *   On success, the pointer to the new allocated ring. NULL on error with
 211  *    rte_errno set appropriately. Possible errno values include:
 212  *    - E_RTE_NO_CONFIG - function could not get pointer to rte_config structure
 213  *    - E_RTE_SECONDARY - function was called from a secondary process instance
 214  *    - EINVAL - count provided is not a power of 2
 215  *    - ENOSPC - the maximum number of memzones has already been allocated
 216  *    - EEXIST - a memzone with the same name already exists
 217  *    - ENOMEM - no appropriate memory area found in which to create memzone
 218  */
 219 struct rte_ring *rte_ring_create(const char *name, unsigned count,
 220                                  int socket_id, unsigned flags);
 221 /**
 222  * De-allocate all memory used by the ring.
 223  *
 224  * @param r
 225  *   Ring to free
 226  */
 227 void rte_ring_free(struct rte_ring *r);
 228
 229 /**
 230  * Dump the status of the ring to a file.
 231  *
 232  * @param f
 233  *   A pointer to a file for output
 234  * @param r
 235  *   A pointer to the ring structure.
 236  */
 237 void rte_ring_dump(FILE *f, const struct rte_ring *r);
 238
 239 /* the actual enqueue of pointers on the ring.
 240  * Placed here since identical code needed in both
 241  * single and multi producer enqueue functions */
 242 #define ENQUEUE_PTRS(r, ring_start, prod_head, obj_table, n, obj_type) do { \
 243         unsigned int i; \
 244         const uint32_t size = (r)->size; \
 245         uint32_t idx = prod_head & (r)->mask; \
 246         obj_type *ring = (obj_type *)ring_start; \
 247         if (likely(idx + n < size)) { \
 248                 for (i = 0; i < (n & ((~(unsigned)0x3))); i+=4, idx+=4) { \
 249                         ring[idx] = obj_table[i]; \
 250                         ring[idx+1] = obj_table[i+1]; \
 251                         ring[idx+2] = obj_table[i+2]; \
 252                         ring[idx+3] = obj_table[i+3]; \
 253                 } \
 254                 switch (n & 0x3) { \
 255                 case 3: \
 256                         ring[idx++] = obj_table[i++]; /* fallthrough */ \
 257                 case 2: \
 258                         ring[idx++] = obj_table[i++]; /* fallthrough */ \
 259                 case 1: \
 260                         ring[idx++] = obj_table[i++]; \
 261                 } \
 262         } else { \
 263                 for (i = 0; idx < size; i++, idx++)\
 264                         ring[idx] = obj_table[i]; \
 265                 for (idx = 0; i < n; i++, idx++) \
 266                         ring[idx] = obj_table[i]; \
 267         } \
 268 } while (0)
 269
 270 /* the actual copy of pointers on the ring to obj_table.
 271  * Placed here since identical code needed in both
 272  * single and multi consumer dequeue functions */
 273 #define DEQUEUE_PTRS(r, ring_start, cons_head, obj_table, n, obj_type) do { \
 274         unsigned int i; \
 275         uint32_t idx = cons_head & (r)->mask; \
 276         const uint32_t size = (r)->size; \
 277         obj_type *ring = (obj_type *)ring_start; \
 278         if (likely(idx + n < size)) { \
 279                 for (i = 0; i < (n & (~(unsigned)0x3)); i+=4, idx+=4) {\
 280                         obj_table[i] = ring[idx]; \
 281                         obj_table[i+1] = ring[idx+1]; \
 282                         obj_table[i+2] = ring[idx+2]; \
 283                         obj_table[i+3] = ring[idx+3]; \
 284                 } \
 285                 switch (n & 0x3) { \
 286                 case 3: \
 287                         obj_table[i++] = ring[idx++]; /* fallthrough */ \
 288                 case 2: \
 289                         obj_table[i++] = ring[idx++]; /* fallthrough */ \
 290                 case 1: \
 291                         obj_table[i++] = ring[idx++]; \
 292                 } \
 293         } else { \
 294                 for (i = 0; idx < size; i++, idx++) \
 295                         obj_table[i] = ring[idx]; \
 296                 for (idx = 0; i < n; i++, idx++) \
 297                         obj_table[i] = ring[idx]; \
 298         } \
 299 } while (0)
 300
 301 /* Between load and load. there might be cpu reorder in weak model
 302  * (powerpc/arm).
 303  * There are 2 choices for the users
 304  * 1.use rmb() memory barrier
 305  * 2.use one-direction load_acquire/store_release barrier,defined by
 306  * CONFIG_RTE_USE_C11_MEM_MODEL=y
 307  * It depends on performance test results.
 308  * By default, move common functions to rte_ring_generic.h
 309  */
 310 #ifdef RTE_USE_C11_MEM_MODEL
 311 #include "rte_ring_c11_mem.h"
 312 #else
 313 #include "rte_ring_generic.h"
 314 #endif
 315
 316 /**
 317  * @internal Enqueue several objects on the ring
 318  *
 319   * @param r
 320  *   A pointer to the ring structure.
 321  * @param obj_table
 322  *   A pointer to a table of void * pointers (objects).
 323  * @param n
 324  *   The number of objects to add in the ring from the obj_table.
 325  * @param behavior
 326  *   RTE_RING_QUEUE_FIXED:    Enqueue a fixed number of items from a ring
 327  *   RTE_RING_QUEUE_VARIABLE: Enqueue as many items as possible from ring
 328  * @param is_sp
 329  *   Indicates whether to use single producer or multi-producer head update
 330  * @param free_space
 331  *   returns the amount of space after the enqueue operation has finished
 332  * @return
 333  *   Actual number of objects enqueued.
 334  *   If behavior == RTE_RING_QUEUE_FIXED, this will be 0 or n only.
 335  */
 336 static __rte_always_inline unsigned int
 337 __rte_ring_do_enqueue(struct rte_ring *r, void * const *obj_table,
 338                  unsigned int n, enum rte_ring_queue_behavior behavior,
 339                  unsigned int is_sp, unsigned int *free_space)
 340 {
 341         uint32_t prod_head, prod_next;
 342         uint32_t free_entries;
 343
 344         n = __rte_ring_move_prod_head(r, is_sp, n, behavior,
 345                         &prod_head, &prod_next, &free_entries);
 346         if (n == 0)
 347                 goto end;
 348
 349         ENQUEUE_PTRS(r, &r[1], prod_head, obj_table, n, void *);
 350
 351         update_tail(&r->prod, prod_head, prod_next, is_sp, 1);
 352 end:
 353         if (free_space != NULL)
 354                 *free_space = free_entries - n;
 355         return n;
 356 }
 357
 358 /**
 359  * @internal Dequeue several objects from the ring
 360  *
 361  * @param r
 362  *   A pointer to the ring structure.
 363  * @param obj_table
 364  *   A pointer to a table of void * pointers (objects).
 365  * @param n
 366  *   The number of objects to pull from the ring.
 367  * @param behavior
 368  *   RTE_RING_QUEUE_FIXED:    Dequeue a fixed number of items from a ring
 369  *   RTE_RING_QUEUE_VARIABLE: Dequeue as many items as possible from ring
 370  * @param is_sc
 371  *   Indicates whether to use single consumer or multi-consumer head update
 372  * @param available
 373  *   returns the number of remaining ring entries after the dequeue has finished
 374  * @return
 375  *   - Actual number of objects dequeued.
 376  *     If behavior == RTE_RING_QUEUE_FIXED, this will be 0 or n only.
 377  */
 378 static __rte_always_inline unsigned int
 379 __rte_ring_do_dequeue(struct rte_ring *r, void **obj_table,
 380                  unsigned int n, enum rte_ring_queue_behavior behavior,
 381                  unsigned int is_sc, unsigned int *available)
 382 {
 383         uint32_t cons_head, cons_next;
 384         uint32_t entries;
 385
 386         n = __rte_ring_move_cons_head(r, (int)is_sc, n, behavior,
 387                         &cons_head, &cons_next, &entries);
 388         if (n == 0)
 389                 goto end;
 390
 391         DEQUEUE_PTRS(r, &r[1], cons_head, obj_table, n, void *);
 392
 393         update_tail(&r->cons, cons_head, cons_next, is_sc, 0);
 394
 395 end:
 396         if (available != NULL)
 397                 *available = entries - n;
 398         return n;
 399 }
 400
 401 /**
 402  * Enqueue several objects on the ring (multi-producers safe).
 403  *
 404  * This function uses a "compare and set" instruction to move the
 405  * producer index atomically.
 406  *
 407  * @param r
 408  *   A pointer to the ring structure.
 409  * @param obj_table
 410  *   A pointer to a table of void * pointers (objects).
 411  * @param n
 412  *   The number of objects to add in the ring from the obj_table.
 413  * @param free_space
 414  *   if non-NULL, returns the amount of space in the ring after the
 415  *   enqueue operation has finished.
 416  * @return
 417  *   The number of objects enqueued, either 0 or n
 418  */
 419 static __rte_always_inline unsigned int
 420 rte_ring_mp_enqueue_bulk(struct rte_ring *r, void * const *obj_table,
 421                          unsigned int n, unsigned int *free_space)
 422 {
 423         return __rte_ring_do_enqueue(r, obj_table, n, RTE_RING_QUEUE_FIXED,
 424                         __IS_MP, free_space);
 425 }
 426
 427 /**
 428  * Enqueue several objects on a ring (NOT multi-producers safe).
 429  *
 430  * @param r
 431  *   A pointer to the ring structure.
 432  * @param obj_table
 433  *   A pointer to a table of void * pointers (objects).
 434  * @param n
 435  *   The number of objects to add in the ring from the obj_table.
 436  * @param free_space
 437  *   if non-NULL, returns the amount of space in the ring after the
 438  *   enqueue operation has finished.
 439  * @return
 440  *   The number of objects enqueued, either 0 or n
 441  */
 442 static __rte_always_inline unsigned int
 443 rte_ring_sp_enqueue_bulk(struct rte_ring *r, void * const *obj_table,
 444                          unsigned int n, unsigned int *free_space)
 445 {
 446         return __rte_ring_do_enqueue(r, obj_table, n, RTE_RING_QUEUE_FIXED,
 447                         __IS_SP, free_space);
 448 }
 449
 450 /**
 451  * Enqueue several objects on a ring.
 452  *
 453  * This function calls the multi-producer or the single-producer
 454  * version depending on the default behavior that was specified at
 455  * ring creation time (see flags).
 456  *
 457  * @param r
 458  *   A pointer to the ring structure.
 459  * @param obj_table
 460  *   A pointer to a table of void * pointers (objects).
 461  * @param n
 462  *   The number of objects to add in the ring from the obj_table.
 463  * @param free_space
 464  *   if non-NULL, returns the amount of space in the ring after the
 465  *   enqueue operation has finished.
 466  * @return
 467  *   The number of objects enqueued, either 0 or n
 468  */
 469 static __rte_always_inline unsigned int
 470 rte_ring_enqueue_bulk(struct rte_ring *r, void * const *obj_table,
 471                       unsigned int n, unsigned int *free_space)
 472 {
 473         return __rte_ring_do_enqueue(r, obj_table, n, RTE_RING_QUEUE_FIXED,
 474                         r->prod.single, free_space);
 475 }
 476
 477 /**
 478  * Enqueue one object on a ring (multi-producers safe).
 479  *
 480  * This function uses a "compare and set" instruction to move the
 481  * producer index atomically.
 482  *
 483  * @param r
 484  *   A pointer to the ring structure.
 485  * @param obj
 486  *   A pointer to the object to be added.
 487  * @return
 488  *   - 0: Success; objects enqueued.
 489  *   - -ENOBUFS: Not enough room in the ring to enqueue; no object is enqueued.
 490  */
 491 static __rte_always_inline int
 492 rte_ring_mp_enqueue(struct rte_ring *r, void *obj)
 493 {
 494         return rte_ring_mp_enqueue_bulk(r, &obj, 1, NULL) ? 0 : -ENOBUFS;
 495 }
 496
 497 /**
 498  * Enqueue one object on a ring (NOT multi-producers safe).
 499  *
 500  * @param r
 501  *   A pointer to the ring structure.
 502  * @param obj
 503  *   A pointer to the object to be added.
 504  * @return
 505  *   - 0: Success; objects enqueued.
 506  *   - -ENOBUFS: Not enough room in the ring to enqueue; no object is enqueued.
 507  */
 508 static __rte_always_inline int
 509 rte_ring_sp_enqueue(struct rte_ring *r, void *obj)
 510 {
 511         return rte_ring_sp_enqueue_bulk(r, &obj, 1, NULL) ? 0 : -ENOBUFS;
 512 }
 513
 514 /**
 515  * Enqueue one object on a ring.
 516  *
 517  * This function calls the multi-producer or the single-producer
 518  * version, depending on the default behaviour that was specified at
 519  * ring creation time (see flags).
 520  *
 521  * @param r
 522  *   A pointer to the ring structure.
 523  * @param obj
 524  *   A pointer to the object to be added.
 525  * @return
 526  *   - 0: Success; objects enqueued.
 527  *   - -ENOBUFS: Not enough room in the ring to enqueue; no object is enqueued.
 528  */
 529 static __rte_always_inline int
 530 rte_ring_enqueue(struct rte_ring *r, void *obj)
 531 {
 532         return rte_ring_enqueue_bulk(r, &obj, 1, NULL) ? 0 : -ENOBUFS;
 533 }
 534
 535 /**
 536  * Dequeue several objects from a ring (multi-consumers safe).
 537  *
 538  * This function uses a "compare and set" instruction to move the
 539  * consumer index atomically.
 540  *
 541  * @param r
 542  *   A pointer to the ring structure.
 543  * @param obj_table
 544  *   A pointer to a table of void * pointers (objects) that will be filled.
 545  * @param n
 546  *   The number of objects to dequeue from the ring to the obj_table.
 547  * @param available
 548  *   If non-NULL, returns the number of remaining ring entries after the
 549  *   dequeue has finished.
 550  * @return
 551  *   The number of objects dequeued, either 0 or n
 552  */
 553 static __rte_always_inline unsigned int
 554 rte_ring_mc_dequeue_bulk(struct rte_ring *r, void **obj_table,
 555                 unsigned int n, unsigned int *available)
 556 {
 557         return __rte_ring_do_dequeue(r, obj_table, n, RTE_RING_QUEUE_FIXED,
 558                         __IS_MC, available);
 559 }
 560
 561 /**
 562  * Dequeue several objects from a ring (NOT multi-consumers safe).
 563  *
 564  * @param r
 565  *   A pointer to the ring structure.
 566  * @param obj_table
 567  *   A pointer to a table of void * pointers (objects) that will be filled.
 568  * @param n
 569  *   The number of objects to dequeue from the ring to the obj_table,
 570  *   must be strictly positive.
 571  * @param available
 572  *   If non-NULL, returns the number of remaining ring entries after the
 573  *   dequeue has finished.
 574  * @return
 575  *   The number of objects dequeued, either 0 or n
 576  */
 577 static __rte_always_inline unsigned int
 578 rte_ring_sc_dequeue_bulk(struct rte_ring *r, void **obj_table,
 579                 unsigned int n, unsigned int *available)
 580 {
 581         return __rte_ring_do_dequeue(r, obj_table, n, RTE_RING_QUEUE_FIXED,
 582                         __IS_SC, available);
 583 }
 584
 585 /**
 586  * Dequeue several objects from a ring.
 587  *
 588  * This function calls the multi-consumers or the single-consumer
 589  * version, depending on the default behaviour that was specified at
 590  * ring creation time (see flags).
 591  *
 592  * @param r
 593  *   A pointer to the ring structure.
 594  * @param obj_table
 595  *   A pointer to a table of void * pointers (objects) that will be filled.
 596  * @param n
 597  *   The number of objects to dequeue from the ring to the obj_table.
 598  * @param available
 599  *   If non-NULL, returns the number of remaining ring entries after the
 600  *   dequeue has finished.
 601  * @return
 602  *   The number of objects dequeued, either 0 or n
 603  */
 604 static __rte_always_inline unsigned int
 605 rte_ring_dequeue_bulk(struct rte_ring *r, void **obj_table, unsigned int n,
 606                 unsigned int *available)
 607 {
 608         return __rte_ring_do_dequeue(r, obj_table, n, RTE_RING_QUEUE_FIXED,
 609                                 r->cons.single, available);
 610 }
 611
 612 /**
 613  * Dequeue one object from a ring (multi-consumers safe).
 614  *
 615  * This function uses a "compare and set" instruction to move the
 616  * consumer index atomically.
 617  *
 618  * @param r
 619  *   A pointer to the ring structure.
 620  * @param obj_p
 621  *   A pointer to a void * pointer (object) that will be filled.
 622  * @return
 623  *   - 0: Success; objects dequeued.
 624  *   - -ENOENT: Not enough entries in the ring to dequeue; no object is
 625  *     dequeued.
 626  */
 627 static __rte_always_inline int
 628 rte_ring_mc_dequeue(struct rte_ring *r, void **obj_p)
 629 {
 630         return rte_ring_mc_dequeue_bulk(r, obj_p, 1, NULL)  ? 0 : -ENOENT;
 631 }
 632
 633 /**
 634  * Dequeue one object from a ring (NOT multi-consumers safe).
 635  *
 636  * @param r
 637  *   A pointer to the ring structure.
 638  * @param obj_p
 639  *   A pointer to a void * pointer (object) that will be filled.
 640  * @return
 641  *   - 0: Success; objects dequeued.
 642  *   - -ENOENT: Not enough entries in the ring to dequeue, no object is
 643  *     dequeued.
 644  */
 645 static __rte_always_inline int
 646 rte_ring_sc_dequeue(struct rte_ring *r, void **obj_p)
 647 {
 648         return rte_ring_sc_dequeue_bulk(r, obj_p, 1, NULL) ? 0 : -ENOENT;
 649 }
 650
 651 /**
 652  * Dequeue one object from a ring.
 653  *
 654  * This function calls the multi-consumers or the single-consumer
 655  * version depending on the default behaviour that was specified at
 656  * ring creation time (see flags).
 657  *
 658  * @param r
 659  *   A pointer to the ring structure.
 660  * @param obj_p
 661  *   A pointer to a void * pointer (object) that will be filled.
 662  * @return
 663  *   - 0: Success, objects dequeued.
 664  *   - -ENOENT: Not enough entries in the ring to dequeue, no object is
 665  *     dequeued.
 666  */
 667 static __rte_always_inline int
 668 rte_ring_dequeue(struct rte_ring *r, void **obj_p)
 669 {
 670         return rte_ring_dequeue_bulk(r, obj_p, 1, NULL) ? 0 : -ENOENT;
 671 }
 672
 673 /**
 674  * Return the number of entries in a ring.
 675  *
 676  * @param r
 677  *   A pointer to the ring structure.
 678  * @return
 679  *   The number of entries in the ring.
 680  */
 681 static inline unsigned
 682 rte_ring_count(const struct rte_ring *r)
 683 {
 684         uint32_t prod_tail = r->prod.tail;
 685         uint32_t cons_tail = r->cons.tail;
 686         uint32_t count = (prod_tail - cons_tail) & r->mask;
 687         return (count > r->capacity) ? r->capacity : count;
 688 }
 689
 690 /**
 691  * Return the number of free entries in a ring.
 692  *
 693  * @param r
 694  *   A pointer to the ring structure.
 695  * @return
 696  *   The number of free entries in the ring.
 697  */
 698 static inline unsigned
 699 rte_ring_free_count(const struct rte_ring *r)
 700 {
 701         return r->capacity - rte_ring_count(r);
 702 }
 703
 704 /**
 705  * Test if a ring is full.
 706  *
 707  * @param r
 708  *   A pointer to the ring structure.
 709  * @return
 710  *   - 1: The ring is full.
 711  *   - 0: The ring is not full.
 712  */
 713 static inline int
 714 rte_ring_full(const struct rte_ring *r)
 715 {
 716         return rte_ring_free_count(r) == 0;
 717 }
 718
 719 /**
 720  * Test if a ring is empty.
 721  *
 722  * @param r
 723  *   A pointer to the ring structure.
 724  * @return
 725  *   - 1: The ring is empty.
 726  *   - 0: The ring is not empty.
 727  */
 728 static inline int
 729 rte_ring_empty(const struct rte_ring *r)
 730 {
 731         return rte_ring_count(r) == 0;
 732 }
 733
 734 /**
 735  * Return the size of the ring.
 736  *
 737  * @param r
 738  *   A pointer to the ring structure.
 739  * @return
 740  *   The size of the data store used by the ring.
 741  *   NOTE: this is not the same as the usable space in the ring. To query that
 742  *   use ``rte_ring_get_capacity()``.
 743  */
 744 static inline unsigned int
 745 rte_ring_get_size(const struct rte_ring *r)
 746 {
 747         return r->size;
 748 }
 749
 750 /**
 751  * Return the number of elements which can be stored in the ring.
 752  *
 753  * @param r
 754  *   A pointer to the ring structure.
 755  * @return
 756  *   The usable size of the ring.
 757  */
 758 static inline unsigned int
 759 rte_ring_get_capacity(const struct rte_ring *r)
 760 {
 761         return r->capacity;
 762 }
 763
 764 /**
 765  * Dump the status of all rings on the console
 766  *
 767  * @param f
 768  *   A pointer to a file for output
 769  */
 770 void rte_ring_list_dump(FILE *f);
 771
 772 /**
 773  * Search a ring from its name
 774  *
 775  * @param name
 776  *   The name of the ring.
 777  * @return
 778  *   The pointer to the ring matching the name, or NULL if not found,
 779  *   with rte_errno set appropriately. Possible rte_errno values include:
 780  *    - ENOENT - required entry not available to return.
 781  */
 782 struct rte_ring *rte_ring_lookup(const char *name);
 783
 784 /**
 785  * Enqueue several objects on the ring (multi-producers safe).
 786  *
 787  * This function uses a "compare and set" instruction to move the
 788  * producer index atomically.
 789  *
 790  * @param r
 791  *   A pointer to the ring structure.
 792  * @param obj_table
 793  *   A pointer to a table of void * pointers (objects).
 794  * @param n
 795  *   The number of objects to add in the ring from the obj_table.
 796  * @param free_space
 797  *   if non-NULL, returns the amount of space in the ring after the
 798  *   enqueue operation has finished.
 799  * @return
 800  *   - n: Actual number of objects enqueued.
 801  */
 802 static __rte_always_inline unsigned
 803 rte_ring_mp_enqueue_burst(struct rte_ring *r, void * const *obj_table,
 804                          unsigned int n, unsigned int *free_space)
 805 {
 806         return __rte_ring_do_enqueue(r, obj_table, n,
 807                         RTE_RING_QUEUE_VARIABLE, __IS_MP, free_space);
 808 }
 809
 810 /**
 811  * Enqueue several objects on a ring (NOT multi-producers safe).
 812  *
 813  * @param r
 814  *   A pointer to the ring structure.
 815  * @param obj_table
 816  *   A pointer to a table of void * pointers (objects).
 817  * @param n
 818  *   The number of objects to add in the ring from the obj_table.
 819  * @param free_space
 820  *   if non-NULL, returns the amount of space in the ring after the
 821  *   enqueue operation has finished.
 822  * @return
 823  *   - n: Actual number of objects enqueued.
 824  */
 825 static __rte_always_inline unsigned
 826 rte_ring_sp_enqueue_burst(struct rte_ring *r, void * const *obj_table,
 827                          unsigned int n, unsigned int *free_space)
 828 {
 829         return __rte_ring_do_enqueue(r, obj_table, n,
 830                         RTE_RING_QUEUE_VARIABLE, __IS_SP, free_space);
 831 }
 832
 833 /**
 834  * Enqueue several objects on a ring.
 835  *
 836  * This function calls the multi-producer or the single-producer
 837  * version depending on the default behavior that was specified at
 838  * ring creation time (see flags).
 839  *
 840  * @param r
 841  *   A pointer to the ring structure.
 842  * @param obj_table
 843  *   A pointer to a table of void * pointers (objects).
 844  * @param n
 845  *   The number of objects to add in the ring from the obj_table.
 846  * @param free_space
 847  *   if non-NULL, returns the amount of space in the ring after the
 848  *   enqueue operation has finished.
 849  * @return
 850  *   - n: Actual number of objects enqueued.
 851  */
 852 static __rte_always_inline unsigned
 853 rte_ring_enqueue_burst(struct rte_ring *r, void * const *obj_table,
 854                       unsigned int n, unsigned int *free_space)
 855 {
 856         return __rte_ring_do_enqueue(r, obj_table, n, RTE_RING_QUEUE_VARIABLE,
 857                         r->prod.single, free_space);
 858 }
 859
 860 /**
 861  * Dequeue several objects from a ring (multi-consumers safe). When the request
 862  * objects are more than the available objects, only dequeue the actual number
 863  * of objects
 864  *
 865  * This function uses a "compare and set" instruction to move the
 866  * consumer index atomically.
 867  *
 868  * @param r
 869  *   A pointer to the ring structure.
 870  * @param obj_table
 871  *   A pointer to a table of void * pointers (objects) that will be filled.
 872  * @param n
 873  *   The number of objects to dequeue from the ring to the obj_table.
 874  * @param available
 875  *   If non-NULL, returns the number of remaining ring entries after the
 876  *   dequeue has finished.
 877  * @return
 878  *   - n: Actual number of objects dequeued, 0 if ring is empty
 879  */
 880 static __rte_always_inline unsigned
 881 rte_ring_mc_dequeue_burst(struct rte_ring *r, void **obj_table,
 882                 unsigned int n, unsigned int *available)
 883 {
 884         return __rte_ring_do_dequeue(r, obj_table, n,
 885                         RTE_RING_QUEUE_VARIABLE, __IS_MC, available);
 886 }
 887
 888 /**
 889  * Dequeue several objects from a ring (NOT multi-consumers safe).When the
 890  * request objects are more than the available objects, only dequeue the
 891  * actual number of objects
 892  *
 893  * @param r
 894  *   A pointer to the ring structure.
 895  * @param obj_table
 896  *   A pointer to a table of void * pointers (objects) that will be filled.
 897  * @param n
 898  *   The number of objects to dequeue from the ring to the obj_table.
 899  * @param available
 900  *   If non-NULL, returns the number of remaining ring entries after the
 901  *   dequeue has finished.
 902  * @return
 903  *   - n: Actual number of objects dequeued, 0 if ring is empty
 904  */
 905 static __rte_always_inline unsigned
 906 rte_ring_sc_dequeue_burst(struct rte_ring *r, void **obj_table,
 907                 unsigned int n, unsigned int *available)
 908 {
 909         return __rte_ring_do_dequeue(r, obj_table, n,
 910                         RTE_RING_QUEUE_VARIABLE, __IS_SC, available);
 911 }
 912
 913 /**
 914  * Dequeue multiple objects from a ring up to a maximum number.
 915  *
 916  * This function calls the multi-consumers or the single-consumer
 917  * version, depending on the default behaviour that was specified at
 918  * ring creation time (see flags).
 919  *
 920  * @param r
 921  *   A pointer to the ring structure.
 922  * @param obj_table
 923  *   A pointer to a table of void * pointers (objects) that will be filled.
 924  * @param n
 925  *   The number of objects to dequeue from the ring to the obj_table.
 926  * @param available
 927  *   If non-NULL, returns the number of remaining ring entries after the
 928  *   dequeue has finished.
 929  * @return
 930  *   - Number of objects dequeued
 931  */
 932 static __rte_always_inline unsigned
 933 rte_ring_dequeue_burst(struct rte_ring *r, void **obj_table,
 934                 unsigned int n, unsigned int *available)
 935 {
 936         return __rte_ring_do_dequeue(r, obj_table, n,
 937                                 RTE_RING_QUEUE_VARIABLE,
 938                                 r->cons.single, available);
 939 }
 940
 941 #ifdef __cplusplus
 942 }
 943 #endif
 944
 945 #endif /* _RTE_RING_H_ */