From 76cb841cb886eef6b3bee341a2266c76578724ad Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Mon, 6 May 2024 03:02:30 +0200 Subject: Adding upstream version 4.19.249. Signed-off-by: Daniel Baumann --- arch/ia64/include/asm/rwsem.h | 172 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 172 insertions(+) create mode 100644 arch/ia64/include/asm/rwsem.h (limited to 'arch/ia64/include/asm/rwsem.h') diff --git a/arch/ia64/include/asm/rwsem.h b/arch/ia64/include/asm/rwsem.h new file mode 100644 index 000000000..917910607 --- /dev/null +++ b/arch/ia64/include/asm/rwsem.h @@ -0,0 +1,172 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * R/W semaphores for ia64 + * + * Copyright (C) 2003 Ken Chen + * Copyright (C) 2003 Asit Mallick + * Copyright (C) 2005 Christoph Lameter + * + * Based on asm-i386/rwsem.h and other architecture implementation. + * + * 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 0xffffffff00000001 for + * the case of an uncontended lock. 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). + */ + +#ifndef _ASM_IA64_RWSEM_H +#define _ASM_IA64_RWSEM_H + +#ifndef _LINUX_RWSEM_H +#error "Please don't include directly, use instead." +#endif + +#include + +#define RWSEM_UNLOCKED_VALUE __IA64_UL_CONST(0x0000000000000000) +#define RWSEM_ACTIVE_BIAS (1L) +#define RWSEM_ACTIVE_MASK (0xffffffffL) +#define RWSEM_WAITING_BIAS (-0x100000000L) +#define RWSEM_ACTIVE_READ_BIAS RWSEM_ACTIVE_BIAS +#define RWSEM_ACTIVE_WRITE_BIAS (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS) + +/* + * lock for reading + */ +static inline int +___down_read (struct rw_semaphore *sem) +{ + long result = ia64_fetchadd8_acq((unsigned long *)&sem->count.counter, 1); + + return (result < 0); +} + +static inline void +__down_read (struct rw_semaphore *sem) +{ + if (___down_read(sem)) + rwsem_down_read_failed(sem); +} + +static inline int +__down_read_killable (struct rw_semaphore *sem) +{ + if (___down_read(sem)) + if (IS_ERR(rwsem_down_read_failed_killable(sem))) + return -EINTR; + + return 0; +} + +/* + * lock for writing + */ +static inline long +___down_write (struct rw_semaphore *sem) +{ + long old, new; + + do { + old = atomic_long_read(&sem->count); + new = old + RWSEM_ACTIVE_WRITE_BIAS; + } while (atomic_long_cmpxchg_acquire(&sem->count, old, new) != old); + + 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; +} + +/* + * unlock after reading + */ +static inline void +__up_read (struct rw_semaphore *sem) +{ + long result = ia64_fetchadd8_rel((unsigned long *)&sem->count.counter, -1); + + if (result < 0 && (--result & RWSEM_ACTIVE_MASK) == 0) + rwsem_wake(sem); +} + +/* + * unlock after writing + */ +static inline void +__up_write (struct rw_semaphore *sem) +{ + long old, new; + + do { + old = atomic_long_read(&sem->count); + new = old - RWSEM_ACTIVE_WRITE_BIAS; + } while (atomic_long_cmpxchg_release(&sem->count, old, new) != old); + + if (new < 0 && (new & RWSEM_ACTIVE_MASK) == 0) + rwsem_wake(sem); +} + +/* + * trylock for reading -- returns 1 if successful, 0 if contention + */ +static inline int +__down_read_trylock (struct rw_semaphore *sem) +{ + long tmp; + while ((tmp = atomic_long_read(&sem->count)) >= 0) { + if (tmp == atomic_long_cmpxchg_acquire(&sem->count, tmp, tmp+1)) { + return 1; + } + } + return 0; +} + +/* + * trylock for writing -- returns 1 if successful, 0 if contention + */ +static inline int +__down_write_trylock (struct rw_semaphore *sem) +{ + long tmp = atomic_long_cmpxchg_acquire(&sem->count, + RWSEM_UNLOCKED_VALUE, RWSEM_ACTIVE_WRITE_BIAS); + return tmp == RWSEM_UNLOCKED_VALUE; +} + +/* + * downgrade write lock to read lock + */ +static inline void +__downgrade_write (struct rw_semaphore *sem) +{ + long old, new; + + do { + old = atomic_long_read(&sem->count); + new = old - RWSEM_WAITING_BIAS; + } while (atomic_long_cmpxchg_release(&sem->count, old, new) != old); + + if (old < 0) + rwsem_downgrade_wake(sem); +} + +#endif /* _ASM_IA64_RWSEM_H */ -- cgit v1.2.3