| 1 | /* SPDX-License-Identifier: MIT */ |
| 2 | /****************************************************************************** |
| 3 | * ring.h |
| 4 | * |
| 5 | * Shared producer-consumer ring macros. |
| 6 | * |
| 7 | * Tim Deegan and Andrew Warfield November 2004. |
| 8 | */ |
| 9 | |
| 10 | #ifndef __XEN_PUBLIC_IO_RING_H__ |
| 11 | #define __XEN_PUBLIC_IO_RING_H__ |
| 12 | |
| 13 | /* |
| 14 | * When #include'ing this header, you need to provide the following |
| 15 | * declaration upfront: |
| 16 | * - standard integers types (uint8_t, uint16_t, etc) |
| 17 | * They are provided by stdint.h of the standard headers. |
| 18 | * |
| 19 | * In addition, if you intend to use the FLEX macros, you also need to |
| 20 | * provide the following, before invoking the FLEX macros: |
| 21 | * - size_t |
| 22 | * - memcpy |
| 23 | * - grant_ref_t |
| 24 | * These declarations are provided by string.h of the standard headers, |
| 25 | * and grant_table.h from the Xen public headers. |
| 26 | */ |
| 27 | |
| 28 | #include "../xen-compat.h" |
| 29 | |
| 30 | #if __XEN_INTERFACE_VERSION__ < 0x00030208 |
| 31 | #define xen_mb() mb() |
| 32 | #define xen_rmb() rmb() |
| 33 | #define xen_wmb() wmb() |
| 34 | #endif |
| 35 | |
| 36 | typedef unsigned int RING_IDX; |
| 37 | |
| 38 | /* Round a 32-bit unsigned constant down to the nearest power of two. */ |
| 39 | #define __RD2(_x) (((_x) & 0x00000002) ? 0x2 : ((_x) & 0x1)) |
| 40 | #define __RD4(_x) (((_x) & 0x0000000c) ? __RD2((_x)>>2)<<2 : __RD2(_x)) |
| 41 | #define __RD8(_x) (((_x) & 0x000000f0) ? __RD4((_x)>>4)<<4 : __RD4(_x)) |
| 42 | #define __RD16(_x) (((_x) & 0x0000ff00) ? __RD8((_x)>>8)<<8 : __RD8(_x)) |
| 43 | #define __RD32(_x) (((_x) & 0xffff0000) ? __RD16((_x)>>16)<<16 : __RD16(_x)) |
| 44 | |
| 45 | /* |
| 46 | * Calculate size of a shared ring, given the total available space for the |
| 47 | * ring and indexes (_sz), and the name tag of the request/response structure. |
| 48 | * A ring contains as many entries as will fit, rounded down to the nearest |
| 49 | * power of two (so we can mask with (size-1) to loop around). |
| 50 | */ |
| 51 | #define __CONST_RING_SIZE(_s, _sz) \ |
| 52 | (__RD32(((_sz) - offsetof(struct _s##_sring, ring)) / \ |
| 53 | sizeof(((struct _s##_sring *)0)->ring[0]))) |
| 54 | /* |
| 55 | * The same for passing in an actual pointer instead of a name tag. |
| 56 | */ |
| 57 | #define __RING_SIZE(_s, _sz) \ |
| 58 | (__RD32(((_sz) - (long)(_s)->ring + (long)(_s)) / sizeof((_s)->ring[0]))) |
| 59 | |
| 60 | /* |
| 61 | * Macros to make the correct C datatypes for a new kind of ring. |
| 62 | * |
| 63 | * To make a new ring datatype, you need to have two message structures, |
| 64 | * let's say request_t, and response_t already defined. |
| 65 | * |
| 66 | * In a header where you want the ring datatype declared, you then do: |
| 67 | * |
| 68 | * DEFINE_RING_TYPES(mytag, request_t, response_t); |
| 69 | * |
| 70 | * These expand out to give you a set of types, as you can see below. |
| 71 | * The most important of these are: |
| 72 | * |
| 73 | * mytag_sring_t - The shared ring. |
| 74 | * mytag_front_ring_t - The 'front' half of the ring. |
| 75 | * mytag_back_ring_t - The 'back' half of the ring. |
| 76 | * |
| 77 | * To initialize a ring in your code you need to know the location and size |
| 78 | * of the shared memory area (PAGE_SIZE, for instance). To initialise |
| 79 | * the front half: |
| 80 | * |
| 81 | * mytag_front_ring_t ring; |
| 82 | * XEN_FRONT_RING_INIT(&ring, (mytag_sring_t *)shared_page, PAGE_SIZE); |
| 83 | * |
| 84 | * Initializing the back follows similarly (note that only the front |
| 85 | * initializes the shared ring): |
| 86 | * |
| 87 | * mytag_back_ring_t back_ring; |
| 88 | * BACK_RING_INIT(&back_ring, (mytag_sring_t *)shared_page, PAGE_SIZE); |
| 89 | */ |
| 90 | |
| 91 | #define DEFINE_RING_TYPES(__name, __req_t, __rsp_t) \ |
| 92 | \ |
| 93 | /* Shared ring entry */ \ |
| 94 | union __name##_sring_entry { \ |
| 95 | __req_t req; \ |
| 96 | __rsp_t rsp; \ |
| 97 | }; \ |
| 98 | \ |
| 99 | /* Shared ring page */ \ |
| 100 | struct __name##_sring { \ |
| 101 | RING_IDX req_prod, req_event; \ |
| 102 | RING_IDX rsp_prod, rsp_event; \ |
| 103 | union { \ |
| 104 | struct { \ |
| 105 | uint8_t smartpoll_active; \ |
| 106 | } netif; \ |
| 107 | struct { \ |
| 108 | uint8_t msg; \ |
| 109 | } tapif_user; \ |
| 110 | uint8_t pvt_pad[4]; \ |
| 111 | } pvt; \ |
| 112 | uint8_t __pad[44]; \ |
| 113 | union __name##_sring_entry ring[1]; /* variable-length */ \ |
| 114 | }; \ |
| 115 | \ |
| 116 | /* "Front" end's private variables */ \ |
| 117 | struct __name##_front_ring { \ |
| 118 | RING_IDX req_prod_pvt; \ |
| 119 | RING_IDX rsp_cons; \ |
| 120 | unsigned int nr_ents; \ |
| 121 | struct __name##_sring *sring; \ |
| 122 | }; \ |
| 123 | \ |
| 124 | /* "Back" end's private variables */ \ |
| 125 | struct __name##_back_ring { \ |
| 126 | RING_IDX rsp_prod_pvt; \ |
| 127 | RING_IDX req_cons; \ |
| 128 | unsigned int nr_ents; \ |
| 129 | struct __name##_sring *sring; \ |
| 130 | }; \ |
| 131 | \ |
| 132 | /* Syntactic sugar */ \ |
| 133 | typedef struct __name##_sring __name##_sring_t; \ |
| 134 | typedef struct __name##_front_ring __name##_front_ring_t; \ |
| 135 | typedef struct __name##_back_ring __name##_back_ring_t |
| 136 | |
| 137 | /* |
| 138 | * Macros for manipulating rings. |
| 139 | * |
| 140 | * FRONT_RING_whatever works on the "front end" of a ring: here |
| 141 | * requests are pushed on to the ring and responses taken off it. |
| 142 | * |
| 143 | * BACK_RING_whatever works on the "back end" of a ring: here |
| 144 | * requests are taken off the ring and responses put on. |
| 145 | * |
| 146 | * N.B. these macros do NO INTERLOCKS OR FLOW CONTROL. |
| 147 | * This is OK in 1-for-1 request-response situations where the |
| 148 | * requestor (front end) never has more than RING_SIZE()-1 |
| 149 | * outstanding requests. |
| 150 | */ |
| 151 | |
| 152 | /* Initialising empty rings */ |
| 153 | #define SHARED_RING_INIT(_s) do { \ |
| 154 | (_s)->req_prod = (_s)->rsp_prod = 0; \ |
| 155 | (_s)->req_event = (_s)->rsp_event = 1; \ |
| 156 | (void)memset((_s)->pvt.pvt_pad, 0, sizeof((_s)->pvt.pvt_pad)); \ |
| 157 | (void)memset((_s)->__pad, 0, sizeof((_s)->__pad)); \ |
| 158 | } while(0) |
| 159 | |
| 160 | #define FRONT_RING_ATTACH(_r, _s, _i, __size) do { \ |
| 161 | (_r)->req_prod_pvt = (_i); \ |
| 162 | (_r)->rsp_cons = (_i); \ |
| 163 | (_r)->nr_ents = __RING_SIZE(_s, __size); \ |
| 164 | (_r)->sring = (_s); \ |
| 165 | } while (0) |
| 166 | |
| 167 | #define FRONT_RING_INIT(_r, _s, __size) FRONT_RING_ATTACH(_r, _s, 0, __size) |
| 168 | |
| 169 | #define XEN_FRONT_RING_INIT(r, s, size) do { \ |
| 170 | SHARED_RING_INIT(s); \ |
| 171 | FRONT_RING_INIT(r, s, size); \ |
| 172 | } while (0) |
| 173 | |
| 174 | #define BACK_RING_ATTACH(_r, _s, _i, __size) do { \ |
| 175 | (_r)->rsp_prod_pvt = (_i); \ |
| 176 | (_r)->req_cons = (_i); \ |
| 177 | (_r)->nr_ents = __RING_SIZE(_s, __size); \ |
| 178 | (_r)->sring = (_s); \ |
| 179 | } while (0) |
| 180 | |
| 181 | #define BACK_RING_INIT(_r, _s, __size) BACK_RING_ATTACH(_r, _s, 0, __size) |
| 182 | |
| 183 | /* How big is this ring? */ |
| 184 | #define RING_SIZE(_r) \ |
| 185 | ((_r)->nr_ents) |
| 186 | |
| 187 | /* Number of free requests (for use on front side only). */ |
| 188 | #define RING_FREE_REQUESTS(_r) \ |
| 189 | (RING_SIZE(_r) - ((_r)->req_prod_pvt - (_r)->rsp_cons)) |
| 190 | |
| 191 | /* Test if there is an empty slot available on the front ring. |
| 192 | * (This is only meaningful from the front. ) |
| 193 | */ |
| 194 | #define RING_FULL(_r) \ |
| 195 | (RING_FREE_REQUESTS(_r) == 0) |
| 196 | |
| 197 | /* Test if there are outstanding messages to be processed on a ring. */ |
| 198 | #define XEN_RING_NR_UNCONSUMED_RESPONSES(_r) \ |
| 199 | ((_r)->sring->rsp_prod - (_r)->rsp_cons) |
| 200 | |
| 201 | #ifdef __GNUC__ |
| 202 | #define XEN_RING_NR_UNCONSUMED_REQUESTS(_r) ({ \ |
| 203 | unsigned int req = (_r)->sring->req_prod - (_r)->req_cons; \ |
| 204 | unsigned int rsp = RING_SIZE(_r) - \ |
| 205 | ((_r)->req_cons - (_r)->rsp_prod_pvt); \ |
| 206 | req < rsp ? req : rsp; \ |
| 207 | }) |
| 208 | #else |
| 209 | /* Same as above, but without the nice GCC ({ ... }) syntax. */ |
| 210 | #define XEN_RING_NR_UNCONSUMED_REQUESTS(_r) \ |
| 211 | ((((_r)->sring->req_prod - (_r)->req_cons) < \ |
| 212 | (RING_SIZE(_r) - ((_r)->req_cons - (_r)->rsp_prod_pvt))) ? \ |
| 213 | ((_r)->sring->req_prod - (_r)->req_cons) : \ |
| 214 | (RING_SIZE(_r) - ((_r)->req_cons - (_r)->rsp_prod_pvt))) |
| 215 | #endif |
| 216 | |
| 217 | #ifdef XEN_RING_HAS_UNCONSUMED_IS_BOOL |
| 218 | /* |
| 219 | * These variants should only be used in case no caller is abusing them for |
| 220 | * obtaining the number of unconsumed responses/requests. |
| 221 | */ |
| 222 | #define RING_HAS_UNCONSUMED_RESPONSES(_r) \ |
| 223 | (!!XEN_RING_NR_UNCONSUMED_RESPONSES(_r)) |
| 224 | #define RING_HAS_UNCONSUMED_REQUESTS(_r) \ |
| 225 | (!!XEN_RING_NR_UNCONSUMED_REQUESTS(_r)) |
| 226 | #else |
| 227 | #define RING_HAS_UNCONSUMED_RESPONSES(_r) XEN_RING_NR_UNCONSUMED_RESPONSES(_r) |
| 228 | #define RING_HAS_UNCONSUMED_REQUESTS(_r) XEN_RING_NR_UNCONSUMED_REQUESTS(_r) |
| 229 | #endif |
| 230 | |
| 231 | /* Direct access to individual ring elements, by index. */ |
| 232 | #define RING_GET_REQUEST(_r, _idx) \ |
| 233 | (&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].req)) |
| 234 | |
| 235 | #define RING_GET_RESPONSE(_r, _idx) \ |
| 236 | (&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].rsp)) |
| 237 | |
| 238 | /* |
| 239 | * Get a local copy of a request/response. |
| 240 | * |
| 241 | * Use this in preference to RING_GET_{REQUEST,RESPONSE}() so all processing is |
| 242 | * done on a local copy that cannot be modified by the other end. |
| 243 | * |
| 244 | * Note that https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145 may cause this |
| 245 | * to be ineffective where dest is a struct which consists of only bitfields. |
| 246 | */ |
| 247 | #define RING_COPY_(type, r, idx, dest) do { \ |
| 248 | /* Use volatile to force the copy into dest. */ \ |
| 249 | *(dest) = *(volatile __typeof__(dest))RING_GET_##type(r, idx); \ |
| 250 | } while (0) |
| 251 | |
| 252 | #define RING_COPY_REQUEST(r, idx, req) RING_COPY_(REQUEST, r, idx, req) |
| 253 | #define RING_COPY_RESPONSE(r, idx, rsp) RING_COPY_(RESPONSE, r, idx, rsp) |
| 254 | |
| 255 | /* Loop termination condition: Would the specified index overflow the ring? */ |
| 256 | #define RING_REQUEST_CONS_OVERFLOW(_r, _cons) \ |
| 257 | (((_cons) - (_r)->rsp_prod_pvt) >= RING_SIZE(_r)) |
| 258 | |
| 259 | /* Ill-behaved frontend determination: Can there be this many requests? */ |
| 260 | #define RING_REQUEST_PROD_OVERFLOW(_r, _prod) \ |
| 261 | (((_prod) - (_r)->rsp_prod_pvt) > RING_SIZE(_r)) |
| 262 | |
| 263 | /* Ill-behaved backend determination: Can there be this many responses? */ |
| 264 | #define RING_RESPONSE_PROD_OVERFLOW(_r, _prod) \ |
| 265 | (((_prod) - (_r)->rsp_cons) > RING_SIZE(_r)) |
| 266 | |
| 267 | #define RING_PUSH_REQUESTS(_r) do { \ |
| 268 | xen_wmb(); /* back sees requests /before/ updated producer index */ \ |
| 269 | (_r)->sring->req_prod = (_r)->req_prod_pvt; \ |
| 270 | } while (0) |
| 271 | |
| 272 | #define RING_PUSH_RESPONSES(_r) do { \ |
| 273 | xen_wmb(); /* front sees resps /before/ updated producer index */ \ |
| 274 | (_r)->sring->rsp_prod = (_r)->rsp_prod_pvt; \ |
| 275 | } while (0) |
| 276 | |
| 277 | /* |
| 278 | * Notification hold-off (req_event and rsp_event): |
| 279 | * |
| 280 | * When queueing requests or responses on a shared ring, it may not always be |
| 281 | * necessary to notify the remote end. For example, if requests are in flight |
| 282 | * in a backend, the front may be able to queue further requests without |
| 283 | * notifying the back (if the back checks for new requests when it queues |
| 284 | * responses). |
| 285 | * |
| 286 | * When enqueuing requests or responses: |
| 287 | * |
| 288 | * Use RING_PUSH_{REQUESTS,RESPONSES}_AND_CHECK_NOTIFY(). The second argument |
| 289 | * is a boolean return value. True indicates that the receiver requires an |
| 290 | * asynchronous notification. |
| 291 | * |
| 292 | * After dequeuing requests or responses (before sleeping the connection): |
| 293 | * |
| 294 | * Use RING_FINAL_CHECK_FOR_REQUESTS() or RING_FINAL_CHECK_FOR_RESPONSES(). |
| 295 | * The second argument is a boolean return value. True indicates that there |
| 296 | * are pending messages on the ring (i.e., the connection should not be put |
| 297 | * to sleep). |
| 298 | * |
| 299 | * These macros will set the req_event/rsp_event field to trigger a |
| 300 | * notification on the very next message that is enqueued. If you want to |
| 301 | * create batches of work (i.e., only receive a notification after several |
| 302 | * messages have been enqueued) then you will need to create a customised |
| 303 | * version of the FINAL_CHECK macro in your own code, which sets the event |
| 304 | * field appropriately. |
| 305 | */ |
| 306 | |
| 307 | #define RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(_r, _notify) do { \ |
| 308 | RING_IDX __old = (_r)->sring->req_prod; \ |
| 309 | RING_IDX __new = (_r)->req_prod_pvt; \ |
| 310 | xen_wmb(); /* back sees requests /before/ updated producer index */ \ |
| 311 | (_r)->sring->req_prod = __new; \ |
| 312 | xen_mb(); /* back sees new requests /before/ we check req_event */ \ |
| 313 | (_notify) = ((RING_IDX)(__new - (_r)->sring->req_event) < \ |
| 314 | (RING_IDX)(__new - __old)); \ |
| 315 | } while (0) |
| 316 | |
| 317 | #define RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(_r, _notify) do { \ |
| 318 | RING_IDX __old = (_r)->sring->rsp_prod; \ |
| 319 | RING_IDX __new = (_r)->rsp_prod_pvt; \ |
| 320 | xen_wmb(); /* front sees resps /before/ updated producer index */ \ |
| 321 | (_r)->sring->rsp_prod = __new; \ |
| 322 | xen_mb(); /* front sees new resps /before/ we check rsp_event */ \ |
| 323 | (_notify) = ((RING_IDX)(__new - (_r)->sring->rsp_event) < \ |
| 324 | (RING_IDX)(__new - __old)); \ |
| 325 | } while (0) |
| 326 | |
| 327 | #define RING_FINAL_CHECK_FOR_REQUESTS(_r, _work_to_do) do { \ |
| 328 | (_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \ |
| 329 | if (_work_to_do) break; \ |
| 330 | (_r)->sring->req_event = (_r)->req_cons + 1; \ |
| 331 | xen_mb(); \ |
| 332 | (_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \ |
| 333 | } while (0) |
| 334 | |
| 335 | #define RING_FINAL_CHECK_FOR_RESPONSES(_r, _work_to_do) do { \ |
| 336 | (_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \ |
| 337 | if (_work_to_do) break; \ |
| 338 | (_r)->sring->rsp_event = (_r)->rsp_cons + 1; \ |
| 339 | xen_mb(); \ |
| 340 | (_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \ |
| 341 | } while (0) |
| 342 | |
| 343 | |
| 344 | /* |
| 345 | * DEFINE_XEN_FLEX_RING_AND_INTF defines two monodirectional rings and |
| 346 | * functions to check if there is data on the ring, and to read and |
| 347 | * write to them. |
| 348 | * |
| 349 | * DEFINE_XEN_FLEX_RING is similar to DEFINE_XEN_FLEX_RING_AND_INTF, but |
| 350 | * does not define the indexes page. As different protocols can have |
| 351 | * extensions to the basic format, this macro allow them to define their |
| 352 | * own struct. |
| 353 | * |
| 354 | * XEN_FLEX_RING_SIZE |
| 355 | * Convenience macro to calculate the size of one of the two rings |
| 356 | * from the overall order. |
| 357 | * |
| 358 | * $NAME_mask |
| 359 | * Function to apply the size mask to an index, to reduce the index |
| 360 | * within the range [0-size]. |
| 361 | * |
| 362 | * $NAME_read_packet |
| 363 | * Function to read data from the ring. The amount of data to read is |
| 364 | * specified by the "size" argument. |
| 365 | * |
| 366 | * $NAME_write_packet |
| 367 | * Function to write data to the ring. The amount of data to write is |
| 368 | * specified by the "size" argument. |
| 369 | * |
| 370 | * $NAME_get_ring_ptr |
| 371 | * Convenience function that returns a pointer to read/write to the |
| 372 | * ring at the right location. |
| 373 | * |
| 374 | * $NAME_data_intf |
| 375 | * Indexes page, shared between frontend and backend. It also |
| 376 | * contains the array of grant refs. |
| 377 | * |
| 378 | * $NAME_queued |
| 379 | * Function to calculate how many bytes are currently on the ring, |
| 380 | * ready to be read. It can also be used to calculate how much free |
| 381 | * space is currently on the ring (XEN_FLEX_RING_SIZE() - |
| 382 | * $NAME_queued()). |
| 383 | */ |
| 384 | |
| 385 | #ifndef XEN_PAGE_SHIFT |
| 386 | /* The PAGE_SIZE for ring protocols and hypercall interfaces is always |
| 387 | * 4K, regardless of the architecture, and page granularity chosen by |
| 388 | * operating systems. |
| 389 | */ |
| 390 | #define XEN_PAGE_SHIFT 12 |
| 391 | #endif |
| 392 | #define XEN_FLEX_RING_SIZE(order) \ |
| 393 | (1UL << ((order) + XEN_PAGE_SHIFT - 1)) |
| 394 | |
| 395 | #define DEFINE_XEN_FLEX_RING(name) \ |
| 396 | static inline RING_IDX name##_mask(RING_IDX idx, RING_IDX ring_size) \ |
| 397 | { \ |
| 398 | return idx & (ring_size - 1); \ |
| 399 | } \ |
| 400 | \ |
| 401 | static inline unsigned char *name##_get_ring_ptr(unsigned char *buf, \ |
| 402 | RING_IDX idx, \ |
| 403 | RING_IDX ring_size) \ |
| 404 | { \ |
| 405 | return buf + name##_mask(idx, ring_size); \ |
| 406 | } \ |
| 407 | \ |
| 408 | static inline void name##_read_packet(void *opaque, \ |
| 409 | const unsigned char *buf, \ |
| 410 | size_t size, \ |
| 411 | RING_IDX masked_prod, \ |
| 412 | RING_IDX *masked_cons, \ |
| 413 | RING_IDX ring_size) \ |
| 414 | { \ |
| 415 | if (*masked_cons < masked_prod || \ |
| 416 | size <= ring_size - *masked_cons) { \ |
| 417 | memcpy(opaque, buf + *masked_cons, size); \ |
| 418 | } else { \ |
| 419 | memcpy(opaque, buf + *masked_cons, ring_size - *masked_cons); \ |
| 420 | memcpy((unsigned char *)opaque + ring_size - *masked_cons, buf, \ |
| 421 | size - (ring_size - *masked_cons)); \ |
| 422 | } \ |
| 423 | *masked_cons = name##_mask(*masked_cons + size, ring_size); \ |
| 424 | } \ |
| 425 | \ |
| 426 | static inline void name##_write_packet(unsigned char *buf, \ |
| 427 | const void *opaque, \ |
| 428 | size_t size, \ |
| 429 | RING_IDX *masked_prod, \ |
| 430 | RING_IDX masked_cons, \ |
| 431 | RING_IDX ring_size) \ |
| 432 | { \ |
| 433 | if (*masked_prod < masked_cons || \ |
| 434 | size <= ring_size - *masked_prod) { \ |
| 435 | memcpy(buf + *masked_prod, opaque, size); \ |
| 436 | } else { \ |
| 437 | memcpy(buf + *masked_prod, opaque, ring_size - *masked_prod); \ |
| 438 | memcpy(buf, (unsigned char *)opaque + (ring_size - *masked_prod), \ |
| 439 | size - (ring_size - *masked_prod)); \ |
| 440 | } \ |
| 441 | *masked_prod = name##_mask(*masked_prod + size, ring_size); \ |
| 442 | } \ |
| 443 | \ |
| 444 | static inline RING_IDX name##_queued(RING_IDX prod, \ |
| 445 | RING_IDX cons, \ |
| 446 | RING_IDX ring_size) \ |
| 447 | { \ |
| 448 | RING_IDX size; \ |
| 449 | \ |
| 450 | if (prod == cons) \ |
| 451 | return 0; \ |
| 452 | \ |
| 453 | prod = name##_mask(prod, ring_size); \ |
| 454 | cons = name##_mask(cons, ring_size); \ |
| 455 | \ |
| 456 | if (prod == cons) \ |
| 457 | return ring_size; \ |
| 458 | \ |
| 459 | if (prod > cons) \ |
| 460 | size = prod - cons; \ |
| 461 | else \ |
| 462 | size = ring_size - (cons - prod); \ |
| 463 | return size; \ |
| 464 | } \ |
| 465 | \ |
| 466 | struct name##_data { \ |
| 467 | unsigned char *in; /* half of the allocation */ \ |
| 468 | unsigned char *out; /* half of the allocation */ \ |
| 469 | } |
| 470 | |
| 471 | #define DEFINE_XEN_FLEX_RING_AND_INTF(name) \ |
| 472 | struct name##_data_intf { \ |
| 473 | RING_IDX in_cons, in_prod; \ |
| 474 | \ |
| 475 | uint8_t pad1[56]; \ |
| 476 | \ |
| 477 | RING_IDX out_cons, out_prod; \ |
| 478 | \ |
| 479 | uint8_t pad2[56]; \ |
| 480 | \ |
| 481 | RING_IDX ring_order; \ |
| 482 | grant_ref_t ref[]; \ |
| 483 | }; \ |
| 484 | DEFINE_XEN_FLEX_RING(name) |
| 485 | |
| 486 | #endif /* __XEN_PUBLIC_IO_RING_H__ */ |
| 487 | |
| 488 | /* |
| 489 | * Local variables: |
| 490 | * mode: C |
| 491 | * c-file-style: "BSD" |
| 492 | * c-basic-offset: 4 |
| 493 | * tab-width: 4 |
| 494 | * indent-tabs-mode: nil |
| 495 | * End: |
| 496 | */ |