Provide the actual locking functions which make use of the general and spinlock specific rtmutex code.
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| @@ -25,6 +25,7 @@ obj-$(CONFIG_LOCK_SPIN_ON_OWNER) += osq_lock.o · 24 unmodified lines | ||
| 25 | 25 | obj-$(CONFIG_PROVE_LOCKING) += spinlock.o |
| 26 | 26 | obj-$(CONFIG_QUEUED_SPINLOCKS) += qspinlock.o |
| 27 | 27 | obj-$(CONFIG_RT_MUTEXES) += rtmutex_api.o |
| 28 | +obj-$(CONFIG_PREEMPT_RT) += spinlock_rt.o | |
| 28 | 29 | obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock.o |
| 29 | 30 | obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock_debug.o |
| 30 | 31 | obj-$(CONFIG_QUEUED_RWLOCKS) += qrwlock.o |
| @@ -0,0 +1,129 @@ | ||
| 1 | +// SPDX-License-Identifier: GPL-2.0-only | |
| 2 | +/* | |
| 3 | + * PREEMPT_RT substitution for spin/rw_locks | |
| 4 | + * | |
| 5 | + * spinlocks and rwlocks on RT are based on rtmutexes, with a few twists to | |
| 6 | + * resemble the non RT semantics: | |
| 7 | + * | |
| 8 | + * - Contrary to plain rtmutexes, spinlocks and rwlocks are state | |
| 9 | + * preserving. The task state is saved before blocking on the underlying | |
| 10 | + * rtmutex, and restored when the lock has been acquired. Regular wakeups | |
| 11 | + * during that time are redirected to the saved state so no wake up is | |
| 12 | + * missed. | |
| 13 | + * | |
| 14 | + * - Non RT spin/rwlocks disable preemption and eventually interrupts. | |
| 15 | + * Disabling preemption has the side effect of disabling migration and | |
| 16 | + * preventing RCU grace periods. | |
| 17 | + * | |
| 18 | + * The RT substitutions explicitly disable migration and take | |
| 19 | + * rcu_read_lock() across the lock held section. | |
| 20 | + */ | |
| 21 | +#include <linux/spinlock.h> | |
| 22 | +#include <linux/export.h> | |
| 23 | + | |
| 24 | +#define RT_MUTEX_BUILD_SPINLOCKS | |
| 25 | +#include "rtmutex.c" | |
| 26 | + | |
| 27 | +static __always_inline void rtlock_lock(struct rt_mutex_base *rtm) | |
| 28 | +{ | |
| 29 | + if (unlikely(!rt_mutex_cmpxchg_acquire(rtm, NULL, current))) | |
| 30 | + rtlock_slowlock(rtm); | |
| 31 | +} | |
| 32 | + | |
| 33 | +static __always_inline void __rt_spin_lock(spinlock_t *lock) | |
| 34 | +{ | |
| 35 | + ___might_sleep(__FILE__, __LINE__, 0); | |
| 36 | + rtlock_lock(&lock->lock); | |
| 37 | + rcu_read_lock(); | |
| 38 | + migrate_disable(); | |
| 39 | +} | |
| 40 | + | |
| 41 | +void __sched rt_spin_lock(spinlock_t *lock) | |
| 42 | +{ | |
| 43 | + spin_acquire(&lock->dep_map, 0, 0, _RET_IP_); | |
| 44 | + __rt_spin_lock(lock); | |
| 45 | +} | |
| 46 | +EXPORT_SYMBOL(rt_spin_lock); | |
| 47 | + | |
| 48 | +#ifdef CONFIG_DEBUG_LOCK_ALLOC | |
| 49 | +void __sched rt_spin_lock_nested(spinlock_t *lock, int subclass) | |
| 50 | +{ | |
| 51 | + spin_acquire(&lock->dep_map, subclass, 0, _RET_IP_); | |
| 52 | + __rt_spin_lock(lock); | |
| 53 | +} | |
| 54 | +EXPORT_SYMBOL(rt_spin_lock_nested); | |
| 55 | + | |
| 56 | +void __sched rt_spin_lock_nest_lock(spinlock_t *lock, | |
| 57 | + struct lockdep_map *nest_lock) | |
| 58 | +{ | |
| 59 | + spin_acquire_nest(&lock->dep_map, 0, 0, nest_lock, _RET_IP_); | |
| 60 | + __rt_spin_lock(lock); | |
| 61 | +} | |
| 62 | +EXPORT_SYMBOL(rt_spin_lock_nest_lock); | |
| 63 | +#endif | |
| 64 | + | |
| 65 | +void __sched rt_spin_unlock(spinlock_t *lock) | |
| 66 | +{ | |
| 67 | + spin_release(&lock->dep_map, _RET_IP_); | |
| 68 | + migrate_enable(); | |
| 69 | + rcu_read_unlock(); | |
| 70 | + | |
| 71 | + if (unlikely(!rt_mutex_cmpxchg_release(&lock->lock, current, NULL))) | |
| 72 | + rt_mutex_slowunlock(&lock->lock); | |
| 73 | +} | |
| 74 | +EXPORT_SYMBOL(rt_spin_unlock); | |
| 75 | + | |
| 76 | +/* | |
| 77 | + * Wait for the lock to get unlocked: instead of polling for an unlock | |
| 78 | + * (like raw spinlocks do), lock and unlock, to force the kernel to | |
| 79 | + * schedule if there's contention: | |
| 80 | + */ | |
| 81 | +void __sched rt_spin_lock_unlock(spinlock_t *lock) | |
| 82 | +{ | |
| 83 | + spin_lock(lock); | |
| 84 | + spin_unlock(lock); | |
| 85 | +} | |
| 86 | +EXPORT_SYMBOL(rt_spin_lock_unlock); | |
| 87 | + | |
| 88 | +static __always_inline int __rt_spin_trylock(spinlock_t *lock) | |
| 89 | +{ | |
| 90 | + int ret = 1; | |
| 91 | + | |
| 92 | + if (unlikely(!rt_mutex_cmpxchg_acquire(&lock->lock, NULL, current))) | |
| 93 | + ret = rt_mutex_slowtrylock(&lock->lock); | |
| 94 | + | |
| 95 | + if (ret) { | |
| 96 | + spin_acquire(&lock->dep_map, 0, 1, _RET_IP_); | |
| 97 | + rcu_read_lock(); | |
| 98 | + migrate_disable(); | |
| 99 | + } | |
| 100 | + return ret; | |
| 101 | +} | |
| 102 | + | |
| 103 | +int __sched rt_spin_trylock(spinlock_t *lock) | |
| 104 | +{ | |
| 105 | + return __rt_spin_trylock(lock); | |
| 106 | +} | |
| 107 | +EXPORT_SYMBOL(rt_spin_trylock); | |
| 108 | + | |
| 109 | +int __sched rt_spin_trylock_bh(spinlock_t *lock) | |
| 110 | +{ | |
| 111 | + int ret; | |
| 112 | + | |
| 113 | + local_bh_disable(); | |
| 114 | + ret = __rt_spin_trylock(lock); | |
| 115 | + if (!ret) | |
| 116 | + local_bh_enable(); | |
| 117 | + return ret; | |
| 118 | +} | |
| 119 | +EXPORT_SYMBOL(rt_spin_trylock_bh); | |
| 120 | + | |
| 121 | +#ifdef CONFIG_DEBUG_LOCK_ALLOC | |
| 122 | +void __rt_spin_lock_init(spinlock_t *lock, const char *name, | |
| 123 | + struct lock_class_key *key) | |
| 124 | +{ | |
| 125 | + debug_check_no_locks_freed((void *)lock, sizeof(*lock)); | |
| 126 | + lockdep_init_map_wait(&lock->dep_map, name, key, 0, LD_WAIT_CONFIG); | |
| 127 | +} | |
| 128 | +EXPORT_SYMBOL(__rt_spin_lock_init); | |
| 129 | +#endif | |