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Diffstat (limited to 'arch/s390/include/asm/rwsem.h')
| -rw-r--r-- | arch/s390/include/asm/rwsem.h | 211 |
1 files changed, 0 insertions, 211 deletions
diff --git a/arch/s390/include/asm/rwsem.h b/arch/s390/include/asm/rwsem.h deleted file mode 100644 index f731b7b518bd..000000000000 --- a/arch/s390/include/asm/rwsem.h +++ /dev/null @@ -1,211 +0,0 @@ -/* SPDX-License-Identifier: GPL-2.0 */ -#ifndef _S390_RWSEM_H -#define _S390_RWSEM_H - -/* - * S390 version - * Copyright IBM Corp. 2002 - * 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 consecutive 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 - -#define RWSEM_UNLOCKED_VALUE 0x0000000000000000L -#define RWSEM_ACTIVE_BIAS 0x0000000000000001L -#define RWSEM_ACTIVE_MASK 0x00000000ffffffffL -#define RWSEM_WAITING_BIAS (-0x0000000100000000L) -#define RWSEM_ACTIVE_READ_BIAS RWSEM_ACTIVE_BIAS -#define RWSEM_ACTIVE_WRITE_BIAS (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS) - -/* - * lock for reading - */ -static inline void __down_read(struct rw_semaphore *sem) -{ - signed long old, new; - - asm volatile( - " lg %0,%2\n" - "0: lgr %1,%0\n" - " aghi %1,%4\n" - " csg %0,%1,%2\n" - " jl 0b" - : "=&d" (old), "=&d" (new), "=Q" (sem->count) - : "Q" (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( - " lg %0,%2\n" - "0: ltgr %1,%0\n" - " jm 1f\n" - " aghi %1,%4\n" - " csg %0,%1,%2\n" - " jl 0b\n" - "1:" - : "=&d" (old), "=&d" (new), "=Q" (sem->count) - : "Q" (sem->count), "i" (RWSEM_ACTIVE_READ_BIAS) - : "cc", "memory"); - return old >= 0 ? 1 : 0; -} - -/* - * lock for writing - */ -static inline long ___down_write(struct rw_semaphore *sem) -{ - signed long old, new, tmp; - - tmp = RWSEM_ACTIVE_WRITE_BIAS; - asm volatile( - " lg %0,%2\n" - "0: lgr %1,%0\n" - " ag %1,%4\n" - " csg %0,%1,%2\n" - " jl 0b" - : "=&d" (old), "=&d" (new), "=Q" (sem->count) - : "Q" (sem->count), "m" (tmp) - : "cc", "memory"); - - return old; -} - -static inline void __down_write(struct rw_semaphore *sem) -{ - if (___down_write(sem)) - rwsem_down_write_failed(sem); -} - -static inline int __down_write_killable(struct rw_semaphore *sem) -{ - if (___down_write(sem)) - if (IS_ERR(rwsem_down_write_failed_killable(sem))) - return -EINTR; - - return 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( - " lg %0,%1\n" - "0: ltgr %0,%0\n" - " jnz 1f\n" - " csg %0,%3,%1\n" - " jl 0b\n" - "1:" - : "=&d" (old), "=Q" (sem->count) - : "Q" (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( - " lg %0,%2\n" - "0: lgr %1,%0\n" - " aghi %1,%4\n" - " csg %0,%1,%2\n" - " jl 0b" - : "=&d" (old), "=&d" (new), "=Q" (sem->count) - : "Q" (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( - " lg %0,%2\n" - "0: lgr %1,%0\n" - " ag %1,%4\n" - " csg %0,%1,%2\n" - " jl 0b" - : "=&d" (old), "=&d" (new), "=Q" (sem->count) - : "Q" (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( - " lg %0,%2\n" - "0: lgr %1,%0\n" - " ag %1,%4\n" - " csg %0,%1,%2\n" - " jl 0b" - : "=&d" (old), "=&d" (new), "=Q" (sem->count) - : "Q" (sem->count), "m" (tmp) - : "cc", "memory"); - if (new > 1) - rwsem_downgrade_wake(sem); -} - -#endif /* _S390_RWSEM_H */ |