Loading...
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 | #ifndef _S390_RWSEM_H
#define _S390_RWSEM_H
/*
* include/asm-s390/rwsem.h
*
* S390 version
* Copyright (C) 2002 IBM Deutschland Entwicklung GmbH, IBM Corporation
* Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
*
* Based on asm-alpha/semaphore.h and asm-i386/rwsem.h
*/
/*
*
* The MSW of the count is the negated number of active writers and waiting
* lockers, and the LSW is the total number of active locks
*
* The lock count is initialized to 0 (no active and no waiting lockers).
*
* When a writer subtracts WRITE_BIAS, it'll get 0xffff0001 for the case of an
* uncontended lock. This can be determined because XADD returns the old value.
* Readers increment by 1 and see a positive value when uncontended, negative
* if there are writers (and maybe) readers waiting (in which case it goes to
* sleep).
*
* The value of WAITING_BIAS supports up to 32766 waiting processes. This can
* be extended to 65534 by manually checking the whole MSW rather than relying
* on the S flag.
*
* The value of ACTIVE_BIAS supports up to 65535 active processes.
*
* This should be totally fair - if anything is waiting, a process that wants a
* lock will go to the back of the queue. When the currently active lock is
* released, if there's a writer at the front of the queue, then that and only
* that will be woken up; if there's a bunch of consequtive readers at the
* front, then they'll all be woken up, but no other readers will be.
*/
#ifndef _LINUX_RWSEM_H
#error "please don't include asm/rwsem.h directly, use linux/rwsem.h instead"
#endif
#ifdef __KERNEL__
#include <linux/list.h>
#include <linux/spinlock.h>
struct rwsem_waiter;
extern struct rw_semaphore *rwsem_down_read_failed(struct rw_semaphore *);
extern struct rw_semaphore *rwsem_down_write_failed(struct rw_semaphore *);
extern struct rw_semaphore *rwsem_wake(struct rw_semaphore *);
extern struct rw_semaphore *rwsem_downgrade_wake(struct rw_semaphore *);
extern struct rw_semaphore *rwsem_downgrade_write(struct rw_semaphore *);
/*
* the semaphore definition
*/
struct rw_semaphore {
signed long count;
spinlock_t wait_lock;
struct list_head wait_list;
#ifdef CONFIG_DEBUG_LOCK_ALLOC
struct lockdep_map dep_map;
#endif
};
#ifndef __s390x__
#define RWSEM_UNLOCKED_VALUE 0x00000000
#define RWSEM_ACTIVE_BIAS 0x00000001
#define RWSEM_ACTIVE_MASK 0x0000ffff
#define RWSEM_WAITING_BIAS (-0x00010000)
#else /* __s390x__ */
#define RWSEM_UNLOCKED_VALUE 0x0000000000000000L
#define RWSEM_ACTIVE_BIAS 0x0000000000000001L
#define RWSEM_ACTIVE_MASK 0x00000000ffffffffL
#define RWSEM_WAITING_BIAS (-0x0000000100000000L)
#endif /* __s390x__ */
#define RWSEM_ACTIVE_READ_BIAS RWSEM_ACTIVE_BIAS
#define RWSEM_ACTIVE_WRITE_BIAS (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS)
/*
* initialisation
*/
#ifdef CONFIG_DEBUG_LOCK_ALLOC
# define __RWSEM_DEP_MAP_INIT(lockname) , .dep_map = { .name = #lockname }
#else
# define __RWSEM_DEP_MAP_INIT(lockname)
#endif
#define __RWSEM_INITIALIZER(name) \
{ RWSEM_UNLOCKED_VALUE, SPIN_LOCK_UNLOCKED, LIST_HEAD_INIT((name).wait_list) \
__RWSEM_DEP_MAP_INIT(name) }
#define DECLARE_RWSEM(name) \
struct rw_semaphore name = __RWSEM_INITIALIZER(name)
static inline void init_rwsem(struct rw_semaphore *sem)
{
sem->count = RWSEM_UNLOCKED_VALUE;
spin_lock_init(&sem->wait_lock);
INIT_LIST_HEAD(&sem->wait_list);
}
extern void __init_rwsem(struct rw_semaphore *sem, const char *name,
struct lock_class_key *key);
#define init_rwsem(sem) \
do { \
static struct lock_class_key __key; \
\
__init_rwsem((sem), #sem, &__key); \
} while (0)
/*
* lock for reading
*/
static inline void __down_read(struct rw_semaphore *sem)
{
signed long old, new;
asm volatile(
#ifndef __s390x__
" l %0,0(%3)\n"
"0: lr %1,%0\n"
" ahi %1,%5\n"
" cs %0,%1,0(%3)\n"
" jl 0b"
#else /* __s390x__ */
" lg %0,0(%3)\n"
"0: lgr %1,%0\n"
" aghi %1,%5\n"
" csg %0,%1,0(%3)\n"
" jl 0b"
#endif /* __s390x__ */
: "=&d" (old), "=&d" (new), "=m" (sem->count)
: "a" (&sem->count), "m" (sem->count),
"i" (RWSEM_ACTIVE_READ_BIAS) : "cc", "memory");
if (old < 0)
rwsem_down_read_failed(sem);
}
/*
* trylock for reading -- returns 1 if successful, 0 if contention
*/
static inline int __down_read_trylock(struct rw_semaphore *sem)
{
signed long old, new;
asm volatile(
#ifndef __s390x__
" l %0,0(%3)\n"
"0: ltr %1,%0\n"
" jm 1f\n"
" ahi %1,%5\n"
" cs %0,%1,0(%3)\n"
" jl 0b\n"
"1:"
#else /* __s390x__ */
" lg %0,0(%3)\n"
"0: ltgr %1,%0\n"
" jm 1f\n"
" aghi %1,%5\n"
" csg %0,%1,0(%3)\n"
" jl 0b\n"
"1:"
#endif /* __s390x__ */
: "=&d" (old), "=&d" (new), "=m" (sem->count)
: "a" (&sem->count), "m" (sem->count),
"i" (RWSEM_ACTIVE_READ_BIAS) : "cc", "memory");
return old >= 0 ? 1 : 0;
}
/*
* lock for writing
*/
static inline void __down_write_nested(struct rw_semaphore *sem, int subclass)
{
signed long old, new, tmp;
tmp = RWSEM_ACTIVE_WRITE_BIAS;
asm volatile(
#ifndef __s390x__
" l %0,0(%3)\n"
"0: lr %1,%0\n"
" a %1,%5\n"
" cs %0,%1,0(%3)\n"
" jl 0b"
#else /* __s390x__ */
" lg %0,0(%3)\n"
"0: lgr %1,%0\n"
" ag %1,%5\n"
" csg %0,%1,0(%3)\n"
" jl 0b"
#endif /* __s390x__ */
: "=&d" (old), "=&d" (new), "=m" (sem->count)
: "a" (&sem->count), "m" (sem->count), "m" (tmp)
: "cc", "memory");
if (old != 0)
rwsem_down_write_failed(sem);
}
static inline void __down_write(struct rw_semaphore *sem)
{
__down_write_nested(sem, 0);
}
/*
* trylock for writing -- returns 1 if successful, 0 if contention
*/
static inline int __down_write_trylock(struct rw_semaphore *sem)
{
signed long old;
asm volatile(
#ifndef __s390x__
" l %0,0(%2)\n"
"0: ltr %0,%0\n"
" jnz 1f\n"
" cs %0,%4,0(%2)\n"
" jl 0b\n"
#else /* __s390x__ */
" lg %0,0(%2)\n"
"0: ltgr %0,%0\n"
" jnz 1f\n"
" csg %0,%4,0(%2)\n"
" jl 0b\n"
#endif /* __s390x__ */
"1:"
: "=&d" (old), "=m" (sem->count)
: "a" (&sem->count), "m" (sem->count),
"d" (RWSEM_ACTIVE_WRITE_BIAS) : "cc", "memory");
return (old == RWSEM_UNLOCKED_VALUE) ? 1 : 0;
}
/*
* unlock after reading
*/
static inline void __up_read(struct rw_semaphore *sem)
{
signed long old, new;
asm volatile(
#ifndef __s390x__
" l %0,0(%3)\n"
"0: lr %1,%0\n"
" ahi %1,%5\n"
" cs %0,%1,0(%3)\n"
" jl 0b"
#else /* __s390x__ */
" lg %0,0(%3)\n"
"0: lgr %1,%0\n"
" aghi %1,%5\n"
" csg %0,%1,0(%3)\n"
" jl 0b"
#endif /* __s390x__ */
: "=&d" (old), "=&d" (new), "=m" (sem->count)
: "a" (&sem->count), "m" (sem->count),
"i" (-RWSEM_ACTIVE_READ_BIAS)
: "cc", "memory");
if (new < 0)
if ((new & RWSEM_ACTIVE_MASK) == 0)
rwsem_wake(sem);
}
/*
* unlock after writing
*/
static inline void __up_write(struct rw_semaphore *sem)
{
signed long old, new, tmp;
tmp = -RWSEM_ACTIVE_WRITE_BIAS;
asm volatile(
#ifndef __s390x__
" l %0,0(%3)\n"
"0: lr %1,%0\n"
" a %1,%5\n"
" cs %0,%1,0(%3)\n"
" jl 0b"
#else /* __s390x__ */
" lg %0,0(%3)\n"
"0: lgr %1,%0\n"
" ag %1,%5\n"
" csg %0,%1,0(%3)\n"
" jl 0b"
#endif /* __s390x__ */
: "=&d" (old), "=&d" (new), "=m" (sem->count)
: "a" (&sem->count), "m" (sem->count), "m" (tmp)
: "cc", "memory");
if (new < 0)
if ((new & RWSEM_ACTIVE_MASK) == 0)
rwsem_wake(sem);
}
/*
* downgrade write lock to read lock
*/
static inline void __downgrade_write(struct rw_semaphore *sem)
{
signed long old, new, tmp;
tmp = -RWSEM_WAITING_BIAS;
asm volatile(
#ifndef __s390x__
" l %0,0(%3)\n"
"0: lr %1,%0\n"
" a %1,%5\n"
" cs %0,%1,0(%3)\n"
" jl 0b"
#else /* __s390x__ */
" lg %0,0(%3)\n"
"0: lgr %1,%0\n"
" ag %1,%5\n"
" csg %0,%1,0(%3)\n"
" jl 0b"
#endif /* __s390x__ */
: "=&d" (old), "=&d" (new), "=m" (sem->count)
: "a" (&sem->count), "m" (sem->count), "m" (tmp)
: "cc", "memory");
if (new > 1)
rwsem_downgrade_wake(sem);
}
/*
* implement atomic add functionality
*/
static inline void rwsem_atomic_add(long delta, struct rw_semaphore *sem)
{
signed long old, new;
asm volatile(
#ifndef __s390x__
" l %0,0(%3)\n"
"0: lr %1,%0\n"
" ar %1,%5\n"
" cs %0,%1,0(%3)\n"
" jl 0b"
#else /* __s390x__ */
" lg %0,0(%3)\n"
"0: lgr %1,%0\n"
" agr %1,%5\n"
" csg %0,%1,0(%3)\n"
" jl 0b"
#endif /* __s390x__ */
: "=&d" (old), "=&d" (new), "=m" (sem->count)
: "a" (&sem->count), "m" (sem->count), "d" (delta)
: "cc", "memory");
}
/*
* implement exchange and add functionality
*/
static inline long rwsem_atomic_update(long delta, struct rw_semaphore *sem)
{
signed long old, new;
asm volatile(
#ifndef __s390x__
" l %0,0(%3)\n"
"0: lr %1,%0\n"
" ar %1,%5\n"
" cs %0,%1,0(%3)\n"
" jl 0b"
#else /* __s390x__ */
" lg %0,0(%3)\n"
"0: lgr %1,%0\n"
" agr %1,%5\n"
" csg %0,%1,0(%3)\n"
" jl 0b"
#endif /* __s390x__ */
: "=&d" (old), "=&d" (new), "=m" (sem->count)
: "a" (&sem->count), "m" (sem->count), "d" (delta)
: "cc", "memory");
return new;
}
static inline int rwsem_is_locked(struct rw_semaphore *sem)
{
return (sem->count != 0);
}
#endif /* __KERNEL__ */
#endif /* _S390_RWSEM_H */
|