include/linux/nodemask.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef __LINUX_NODEMASK_H
   3 #define __LINUX_NODEMASK_H
   4
   5 /*
   6  * Nodemasks provide a bitmap suitable for representing the
   7  * set of Node's in a system, one bit position per Node number.
   8  *
   9  * See detailed comments in the file linux/bitmap.h describing the
  10  * data type on which these nodemasks are based.
  11  *
  12  * For details of nodemask_parse_user(), see bitmap_parse_user() in
  13  * lib/bitmap.c.  For details of nodelist_parse(), see bitmap_parselist(),
  14  * also in bitmap.c.  For details of node_remap(), see bitmap_bitremap in
  15  * lib/bitmap.c.  For details of nodes_remap(), see bitmap_remap in
  16  * lib/bitmap.c.  For details of nodes_onto(), see bitmap_onto in
  17  * lib/bitmap.c.  For details of nodes_fold(), see bitmap_fold in
  18  * lib/bitmap.c.
  19  *
  20  * The available nodemask operations are:
  21  *
  22  * void node_set(node, mask)            turn on bit 'node' in mask
  23  * void node_clear(node, mask)          turn off bit 'node' in mask
  24  * void nodes_setall(mask)              set all bits
  25  * void nodes_clear(mask)               clear all bits
  26  * int node_isset(node, mask)           true iff bit 'node' set in mask
  27  * int node_test_and_set(node, mask)    test and set bit 'node' in mask
  28  *
  29  * void nodes_and(dst, src1, src2)      dst = src1 & src2  [intersection]
  30  * void nodes_or(dst, src1, src2)       dst = src1 | src2  [union]
  31  * void nodes_xor(dst, src1, src2)      dst = src1 ^ src2
  32  * void nodes_andnot(dst, src1, src2)   dst = src1 & ~src2
  33  * void nodes_complement(dst, src)      dst = ~src
  34  *
  35  * int nodes_equal(mask1, mask2)        Does mask1 == mask2?
  36  * int nodes_intersects(mask1, mask2)   Do mask1 and mask2 intersect?
  37  * int nodes_subset(mask1, mask2)       Is mask1 a subset of mask2?
  38  * int nodes_empty(mask)                Is mask empty (no bits sets)?
  39  * int nodes_full(mask)                 Is mask full (all bits sets)?
  40  * int nodes_weight(mask)               Hamming weight - number of set bits
  41  *
  42  * void nodes_shift_right(dst, src, n)  Shift right
  43  * void nodes_shift_left(dst, src, n)   Shift left
  44  *
  45  * unsigned int first_node(mask)        Number lowest set bit, or MAX_NUMNODES
  46  * unsigend int next_node(node, mask)   Next node past 'node', or MAX_NUMNODES
  47  * unsigned int next_node_in(node, mask) Next node past 'node', or wrap to first,
  48  *                                      or MAX_NUMNODES
  49  * unsigned int first_unset_node(mask)  First node not set in mask, or
  50  *                                      MAX_NUMNODES
  51  *
  52  * nodemask_t nodemask_of_node(node)    Return nodemask with bit 'node' set
  53  * NODE_MASK_ALL                        Initializer - all bits set
  54  * NODE_MASK_NONE                       Initializer - no bits set
  55  * unsigned long *nodes_addr(mask)      Array of unsigned long's in mask
  56  *
  57  * int nodemask_parse_user(ubuf, ulen, mask)    Parse ascii string as nodemask
  58  * int nodelist_parse(buf, map)         Parse ascii string as nodelist
  59  * int node_remap(oldbit, old, new)     newbit = map(old, new)(oldbit)
  60  * void nodes_remap(dst, src, old, new) *dst = map(old, new)(src)
  61  * void nodes_onto(dst, orig, relmap)   *dst = orig relative to relmap
  62  * void nodes_fold(dst, orig, sz)       dst bits = orig bits mod sz
  63  *
  64  * for_each_node_mask(node, mask)       for-loop node over mask
  65  *
  66  * int num_online_nodes()               Number of online Nodes
  67  * int num_possible_nodes()             Number of all possible Nodes
  68  *
  69  * int node_random(mask)                Random node with set bit in mask
  70  *
  71  * int node_online(node)                Is some node online?
  72  * int node_possible(node)              Is some node possible?
  73  *
  74  * node_set_online(node)                set bit 'node' in node_online_map
  75  * node_set_offline(node)               clear bit 'node' in node_online_map
  76  *
  77  * for_each_node(node)                  for-loop node over node_possible_map
  78  * for_each_online_node(node)           for-loop node over node_online_map
  79  *
  80  * Subtlety:
  81  * 1) The 'type-checked' form of node_isset() causes gcc (3.3.2, anyway)
  82  *    to generate slightly worse code.  So use a simple one-line #define
  83  *    for node_isset(), instead of wrapping an inline inside a macro, the
  84  *    way we do the other calls.
  85  *
  86  * NODEMASK_SCRATCH
  87  * When doing above logical AND, OR, XOR, Remap operations the callers tend to
  88  * need temporary nodemask_t's on the stack. But if NODES_SHIFT is large,
  89  * nodemask_t's consume too much stack space.  NODEMASK_SCRATCH is a helper
  90  * for such situations. See below and CPUMASK_ALLOC also.
  91  */
  92
  93 #include <linux/threads.h>
  94 #include <linux/bitmap.h>
  95 #include <linux/minmax.h>
  96 #include <linux/nodemask_types.h>
  97 #include <linux/numa.h>
  98 #include <linux/random.h>
  99
 100 extern nodemask_t _unused_nodemask_arg_;
 101
 102 /**
 103  * nodemask_pr_args - printf args to output a nodemask
 104  * @maskp: nodemask to be printed
 105  *
 106  * Can be used to provide arguments for '%*pb[l]' when printing a nodemask.
 107  */
 108 #define nodemask_pr_args(maskp) __nodemask_pr_numnodes(maskp), \
 109                                 __nodemask_pr_bits(maskp)
 110 static __always_inline unsigned int __nodemask_pr_numnodes(const nodemask_t *m)
 111 {
 112         return m ? MAX_NUMNODES : 0;
 113 }
 114 static __always_inline const unsigned long *__nodemask_pr_bits(const nodemask_t *m)
 115 {
 116         return m ? m->bits : NULL;
 117 }
 118
 119 /*
 120  * The inline keyword gives the compiler room to decide to inline, or
 121  * not inline a function as it sees best.  However, as these functions
 122  * are called in both __init and non-__init functions, if they are not
 123  * inlined we will end up with a section mismatch error (of the type of
 124  * freeable items not being freed).  So we must use __always_inline here
 125  * to fix the problem.  If other functions in the future also end up in
 126  * this situation they will also need to be annotated as __always_inline
 127  */
 128 #define node_set(node, dst) __node_set((node), &(dst))
 129 static __always_inline void __node_set(int node, volatile nodemask_t *dstp)
 130 {
 131         set_bit(node, dstp->bits);
 132 }
 133
 134 #define node_clear(node, dst) __node_clear((node), &(dst))
 135 static __always_inline void __node_clear(int node, volatile nodemask_t *dstp)
 136 {
 137         clear_bit(node, dstp->bits);
 138 }
 139
 140 #define nodes_setall(dst) __nodes_setall(&(dst), MAX_NUMNODES)
 141 static __always_inline void __nodes_setall(nodemask_t *dstp, unsigned int nbits)
 142 {
 143         bitmap_fill(dstp->bits, nbits);
 144 }
 145
 146 #define nodes_clear(dst) __nodes_clear(&(dst), MAX_NUMNODES)
 147 static __always_inline void __nodes_clear(nodemask_t *dstp, unsigned int nbits)
 148 {
 149         bitmap_zero(dstp->bits, nbits);
 150 }
 151
 152 /* No static inline type checking - see Subtlety (1) above. */
 153 #define node_isset(node, nodemask) test_bit((node), (nodemask).bits)
 154
 155 #define node_test_and_set(node, nodemask) \
 156                         __node_test_and_set((node), &(nodemask))
 157 static __always_inline bool __node_test_and_set(int node, nodemask_t *addr)
 158 {
 159         return test_and_set_bit(node, addr->bits);
 160 }
 161
 162 #define nodes_and(dst, src1, src2) \
 163                         __nodes_and(&(dst), &(src1), &(src2), MAX_NUMNODES)
 164 static __always_inline void __nodes_and(nodemask_t *dstp, const nodemask_t *src1p,
 165                                         const nodemask_t *src2p, unsigned int nbits)
 166 {
 167         bitmap_and(dstp->bits, src1p->bits, src2p->bits, nbits);
 168 }
 169
 170 #define nodes_or(dst, src1, src2) \
 171                         __nodes_or(&(dst), &(src1), &(src2), MAX_NUMNODES)
 172 static __always_inline void __nodes_or(nodemask_t *dstp, const nodemask_t *src1p,
 173                                         const nodemask_t *src2p, unsigned int nbits)
 174 {
 175         bitmap_or(dstp->bits, src1p->bits, src2p->bits, nbits);
 176 }
 177
 178 #define nodes_xor(dst, src1, src2) \
 179                         __nodes_xor(&(dst), &(src1), &(src2), MAX_NUMNODES)
 180 static __always_inline void __nodes_xor(nodemask_t *dstp, const nodemask_t *src1p,
 181                                         const nodemask_t *src2p, unsigned int nbits)
 182 {
 183         bitmap_xor(dstp->bits, src1p->bits, src2p->bits, nbits);
 184 }
 185
 186 #define nodes_andnot(dst, src1, src2) \
 187                         __nodes_andnot(&(dst), &(src1), &(src2), MAX_NUMNODES)
 188 static __always_inline void __nodes_andnot(nodemask_t *dstp, const nodemask_t *src1p,
 189                                         const nodemask_t *src2p, unsigned int nbits)
 190 {
 191         bitmap_andnot(dstp->bits, src1p->bits, src2p->bits, nbits);
 192 }
 193
 194 #define nodes_complement(dst, src) \
 195                         __nodes_complement(&(dst), &(src), MAX_NUMNODES)
 196 static __always_inline void __nodes_complement(nodemask_t *dstp,
 197                                         const nodemask_t *srcp, unsigned int nbits)
 198 {
 199         bitmap_complement(dstp->bits, srcp->bits, nbits);
 200 }
 201
 202 #define nodes_equal(src1, src2) \
 203                         __nodes_equal(&(src1), &(src2), MAX_NUMNODES)
 204 static __always_inline bool __nodes_equal(const nodemask_t *src1p,
 205                                         const nodemask_t *src2p, unsigned int nbits)
 206 {
 207         return bitmap_equal(src1p->bits, src2p->bits, nbits);
 208 }
 209
 210 #define nodes_intersects(src1, src2) \
 211                         __nodes_intersects(&(src1), &(src2), MAX_NUMNODES)
 212 static __always_inline bool __nodes_intersects(const nodemask_t *src1p,
 213                                         const nodemask_t *src2p, unsigned int nbits)
 214 {
 215         return bitmap_intersects(src1p->bits, src2p->bits, nbits);
 216 }
 217
 218 #define nodes_subset(src1, src2) \
 219                         __nodes_subset(&(src1), &(src2), MAX_NUMNODES)
 220 static __always_inline bool __nodes_subset(const nodemask_t *src1p,
 221                                         const nodemask_t *src2p, unsigned int nbits)
 222 {
 223         return bitmap_subset(src1p->bits, src2p->bits, nbits);
 224 }
 225
 226 #define nodes_empty(src) __nodes_empty(&(src), MAX_NUMNODES)
 227 static __always_inline bool __nodes_empty(const nodemask_t *srcp, unsigned int nbits)
 228 {
 229         return bitmap_empty(srcp->bits, nbits);
 230 }
 231
 232 #define nodes_full(nodemask) __nodes_full(&(nodemask), MAX_NUMNODES)
 233 static __always_inline bool __nodes_full(const nodemask_t *srcp, unsigned int nbits)
 234 {
 235         return bitmap_full(srcp->bits, nbits);
 236 }
 237
 238 #define nodes_weight(nodemask) __nodes_weight(&(nodemask), MAX_NUMNODES)
 239 static __always_inline int __nodes_weight(const nodemask_t *srcp, unsigned int nbits)
 240 {
 241         return bitmap_weight(srcp->bits, nbits);
 242 }
 243
 244 #define nodes_shift_right(dst, src, n) \
 245                         __nodes_shift_right(&(dst), &(src), (n), MAX_NUMNODES)
 246 static __always_inline void __nodes_shift_right(nodemask_t *dstp,
 247                                         const nodemask_t *srcp, int n, int nbits)
 248 {
 249         bitmap_shift_right(dstp->bits, srcp->bits, n, nbits);
 250 }
 251
 252 #define nodes_shift_left(dst, src, n) \
 253                         __nodes_shift_left(&(dst), &(src), (n), MAX_NUMNODES)
 254 static __always_inline void __nodes_shift_left(nodemask_t *dstp,
 255                                         const nodemask_t *srcp, int n, int nbits)
 256 {
 257         bitmap_shift_left(dstp->bits, srcp->bits, n, nbits);
 258 }
 259
 260 /* FIXME: better would be to fix all architectures to never return
 261           > MAX_NUMNODES, then the silly min_ts could be dropped. */
 262
 263 #define first_node(src) __first_node(&(src))
 264 static __always_inline unsigned int __first_node(const nodemask_t *srcp)
 265 {
 266         return min_t(unsigned int, MAX_NUMNODES, find_first_bit(srcp->bits, MAX_NUMNODES));
 267 }
 268
 269 #define next_node(n, src) __next_node((n), &(src))
 270 static __always_inline unsigned int __next_node(int n, const nodemask_t *srcp)
 271 {
 272         return min_t(unsigned int, MAX_NUMNODES, find_next_bit(srcp->bits, MAX_NUMNODES, n+1));
 273 }
 274
 275 /*
 276  * Find the next present node in src, starting after node n, wrapping around to
 277  * the first node in src if needed.  Returns MAX_NUMNODES if src is empty.
 278  */
 279 #define next_node_in(n, src) __next_node_in((n), &(src))
 280 static __always_inline unsigned int __next_node_in(int node, const nodemask_t *srcp)
 281 {
 282         unsigned int ret = __next_node(node, srcp);
 283
 284         if (ret == MAX_NUMNODES)
 285                 ret = __first_node(srcp);
 286         return ret;
 287 }
 288
 289 static __always_inline void init_nodemask_of_node(nodemask_t *mask, int node)
 290 {
 291         nodes_clear(*mask);
 292         node_set(node, *mask);
 293 }
 294
 295 #define nodemask_of_node(node)                                          \
 296 ({                                                                      \
 297         typeof(_unused_nodemask_arg_) m;                                \
 298         if (sizeof(m) == sizeof(unsigned long)) {                       \
 299                 m.bits[0] = 1UL << (node);                              \
 300         } else {                                                        \
 301                 init_nodemask_of_node(&m, (node));                      \
 302         }                                                               \
 303         m;                                                              \
 304 })
 305
 306 #define first_unset_node(mask) __first_unset_node(&(mask))
 307 static __always_inline unsigned int __first_unset_node(const nodemask_t *maskp)
 308 {
 309         return min_t(unsigned int, MAX_NUMNODES,
 310                         find_first_zero_bit(maskp->bits, MAX_NUMNODES));
 311 }
 312
 313 #define NODE_MASK_LAST_WORD BITMAP_LAST_WORD_MASK(MAX_NUMNODES)
 314
 315 #if MAX_NUMNODES <= BITS_PER_LONG
 316
 317 #define NODE_MASK_ALL                                                   \
 318 ((nodemask_t) { {                                                       \
 319         [BITS_TO_LONGS(MAX_NUMNODES)-1] = NODE_MASK_LAST_WORD           \
 320 } })
 321
 322 #else
 323
 324 #define NODE_MASK_ALL                                                   \
 325 ((nodemask_t) { {                                                       \
 326         [0 ... BITS_TO_LONGS(MAX_NUMNODES)-2] = ~0UL,                   \
 327         [BITS_TO_LONGS(MAX_NUMNODES)-1] = NODE_MASK_LAST_WORD           \
 328 } })
 329
 330 #endif
 331
 332 #define NODE_MASK_NONE                                                  \
 333 ((nodemask_t) { {                                                       \
 334         [0 ... BITS_TO_LONGS(MAX_NUMNODES)-1] =  0UL                    \
 335 } })
 336
 337 #define nodes_addr(src) ((src).bits)
 338
 339 #define nodemask_parse_user(ubuf, ulen, dst) \
 340                 __nodemask_parse_user((ubuf), (ulen), &(dst), MAX_NUMNODES)
 341 static __always_inline int __nodemask_parse_user(const char __user *buf, int len,
 342                                         nodemask_t *dstp, int nbits)
 343 {
 344         return bitmap_parse_user(buf, len, dstp->bits, nbits);
 345 }
 346
 347 #define nodelist_parse(buf, dst) __nodelist_parse((buf), &(dst), MAX_NUMNODES)
 348 static __always_inline int __nodelist_parse(const char *buf, nodemask_t *dstp, int nbits)
 349 {
 350         return bitmap_parselist(buf, dstp->bits, nbits);
 351 }
 352
 353 #define node_remap(oldbit, old, new) \
 354                 __node_remap((oldbit), &(old), &(new), MAX_NUMNODES)
 355 static __always_inline int __node_remap(int oldbit,
 356                 const nodemask_t *oldp, const nodemask_t *newp, int nbits)
 357 {
 358         return bitmap_bitremap(oldbit, oldp->bits, newp->bits, nbits);
 359 }
 360
 361 #define nodes_remap(dst, src, old, new) \
 362                 __nodes_remap(&(dst), &(src), &(old), &(new), MAX_NUMNODES)
 363 static __always_inline void __nodes_remap(nodemask_t *dstp, const nodemask_t *srcp,
 364                 const nodemask_t *oldp, const nodemask_t *newp, int nbits)
 365 {
 366         bitmap_remap(dstp->bits, srcp->bits, oldp->bits, newp->bits, nbits);
 367 }
 368
 369 #define nodes_onto(dst, orig, relmap) \
 370                 __nodes_onto(&(dst), &(orig), &(relmap), MAX_NUMNODES)
 371 static __always_inline void __nodes_onto(nodemask_t *dstp, const nodemask_t *origp,
 372                 const nodemask_t *relmapp, int nbits)
 373 {
 374         bitmap_onto(dstp->bits, origp->bits, relmapp->bits, nbits);
 375 }
 376
 377 #define nodes_fold(dst, orig, sz) \
 378                 __nodes_fold(&(dst), &(orig), sz, MAX_NUMNODES)
 379 static __always_inline void __nodes_fold(nodemask_t *dstp, const nodemask_t *origp,
 380                 int sz, int nbits)
 381 {
 382         bitmap_fold(dstp->bits, origp->bits, sz, nbits);
 383 }
 384
 385 #if MAX_NUMNODES > 1
 386 #define for_each_node_mask(node, mask)                              \
 387         for ((node) = first_node(mask);                             \
 388              (node) < MAX_NUMNODES;                                 \
 389              (node) = next_node((node), (mask)))
 390 #else /* MAX_NUMNODES == 1 */
 391 #define for_each_node_mask(node, mask)                                  \
 392         for ((node) = 0; (node) < 1 && !nodes_empty(mask); (node)++)
 393 #endif /* MAX_NUMNODES */
 394
 395 /*
 396  * Bitmasks that are kept for all the nodes.
 397  */
 398 enum node_states {
 399         N_POSSIBLE,             /* The node could become online at some point */
 400         N_ONLINE,               /* The node is online */
 401         N_NORMAL_MEMORY,        /* The node has regular memory */
 402 #ifdef CONFIG_HIGHMEM
 403         N_HIGH_MEMORY,          /* The node has regular or high memory */
 404 #else
 405         N_HIGH_MEMORY = N_NORMAL_MEMORY,
 406 #endif
 407         N_MEMORY,               /* The node has memory(regular, high, movable) */
 408         N_CPU,          /* The node has one or more cpus */
 409         N_GENERIC_INITIATOR,    /* The node has one or more Generic Initiators */
 410         NR_NODE_STATES
 411 };
 412
 413 /*
 414  * The following particular system nodemasks and operations
 415  * on them manage all possible and online nodes.
 416  */
 417
 418 extern nodemask_t node_states[NR_NODE_STATES];
 419
 420 #if MAX_NUMNODES > 1
 421 static __always_inline int node_state(int node, enum node_states state)
 422 {
 423         return node_isset(node, node_states[state]);
 424 }
 425
 426 static __always_inline void node_set_state(int node, enum node_states state)
 427 {
 428         __node_set(node, &node_states[state]);
 429 }
 430
 431 static __always_inline void node_clear_state(int node, enum node_states state)
 432 {
 433         __node_clear(node, &node_states[state]);
 434 }
 435
 436 static __always_inline int num_node_state(enum node_states state)
 437 {
 438         return nodes_weight(node_states[state]);
 439 }
 440
 441 #define for_each_node_state(__node, __state) \
 442         for_each_node_mask((__node), node_states[__state])
 443
 444 #define first_online_node       first_node(node_states[N_ONLINE])
 445 #define first_memory_node       first_node(node_states[N_MEMORY])
 446 static __always_inline unsigned int next_online_node(int nid)
 447 {
 448         return next_node(nid, node_states[N_ONLINE]);
 449 }
 450 static __always_inline unsigned int next_memory_node(int nid)
 451 {
 452         return next_node(nid, node_states[N_MEMORY]);
 453 }
 454
 455 extern unsigned int nr_node_ids;
 456 extern unsigned int nr_online_nodes;
 457
 458 static __always_inline void node_set_online(int nid)
 459 {
 460         node_set_state(nid, N_ONLINE);
 461         nr_online_nodes = num_node_state(N_ONLINE);
 462 }
 463
 464 static __always_inline void node_set_offline(int nid)
 465 {
 466         node_clear_state(nid, N_ONLINE);
 467         nr_online_nodes = num_node_state(N_ONLINE);
 468 }
 469
 470 #else
 471
 472 static __always_inline int node_state(int node, enum node_states state)
 473 {
 474         return node == 0;
 475 }
 476
 477 static __always_inline void node_set_state(int node, enum node_states state)
 478 {
 479 }
 480
 481 static __always_inline void node_clear_state(int node, enum node_states state)
 482 {
 483 }
 484
 485 static __always_inline int num_node_state(enum node_states state)
 486 {
 487         return 1;
 488 }
 489
 490 #define for_each_node_state(node, __state) \
 491         for ( (node) = 0; (node) == 0; (node) = 1)
 492
 493 #define first_online_node       0
 494 #define first_memory_node       0
 495 #define next_online_node(nid)   (MAX_NUMNODES)
 496 #define next_memory_node(nid)   (MAX_NUMNODES)
 497 #define nr_node_ids             1U
 498 #define nr_online_nodes         1U
 499
 500 #define node_set_online(node)      node_set_state((node), N_ONLINE)
 501 #define node_set_offline(node)     node_clear_state((node), N_ONLINE)
 502
 503 #endif
 504
 505 static __always_inline int node_random(const nodemask_t *maskp)
 506 {
 507 #if defined(CONFIG_NUMA) && (MAX_NUMNODES > 1)
 508         int w, bit;
 509
 510         w = nodes_weight(*maskp);
 511         switch (w) {
 512         case 0:
 513                 bit = NUMA_NO_NODE;
 514                 break;
 515         case 1:
 516                 bit = first_node(*maskp);
 517                 break;
 518         default:
 519                 bit = find_nth_bit(maskp->bits, MAX_NUMNODES, get_random_u32_below(w));
 520                 break;
 521         }
 522         return bit;
 523 #else
 524         return 0;
 525 #endif
 526 }
 527
 528 #define node_online_map         node_states[N_ONLINE]
 529 #define node_possible_map       node_states[N_POSSIBLE]
 530
 531 #define num_online_nodes()      num_node_state(N_ONLINE)
 532 #define num_possible_nodes()    num_node_state(N_POSSIBLE)
 533 #define node_online(node)       node_state((node), N_ONLINE)
 534 #define node_possible(node)     node_state((node), N_POSSIBLE)
 535
 536 #define for_each_node(node)        for_each_node_state(node, N_POSSIBLE)
 537 #define for_each_online_node(node) for_each_node_state(node, N_ONLINE)
 538
 539 /*
 540  * For nodemask scratch area.
 541  * NODEMASK_ALLOC(type, name) allocates an object with a specified type and
 542  * name.
 543  */
 544 #if NODES_SHIFT > 8 /* nodemask_t > 32 bytes */
 545 #define NODEMASK_ALLOC(type, name, gfp_flags)   \
 546                         type *name = kmalloc(sizeof(*name), gfp_flags)
 547 #define NODEMASK_FREE(m)                        kfree(m)
 548 #else
 549 #define NODEMASK_ALLOC(type, name, gfp_flags)   type _##name, *name = &_##name
 550 #define NODEMASK_FREE(m)                        do {} while (0)
 551 #endif
 552
 553 /* Example structure for using NODEMASK_ALLOC, used in mempolicy. */
 554 struct nodemask_scratch {
 555         nodemask_t      mask1;
 556         nodemask_t      mask2;
 557 };
 558
 559 #define NODEMASK_SCRATCH(x)                                             \
 560                         NODEMASK_ALLOC(struct nodemask_scratch, x,      \
 561                                         GFP_KERNEL | __GFP_NORETRY)
 562 #define NODEMASK_SCRATCH_FREE(x)        NODEMASK_FREE(x)
 563
 564
 565 #endif /* __LINUX_NODEMASK_H */