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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118/* SPDX-License-Identifier: GPL-2.0 */#ifndef __LINUX_BIT_SPINLOCK_H#define __LINUX_BIT_SPINLOCK_H
#include <linux/kernel.h>#include <linux/preempt.h>#include <linux/atomic.h>#include <linux/bug.h>
#include <asm/processor.h> /* for cpu_relax() */
/* * For static context analysis, we need a unique token for each possible bit * that can be used as a bit_spinlock. The easiest way to do that is to create a * fake context that we can cast to with the __bitlock(bitnum, addr) macro * below, which will give us unique instances for each (bit, addr) pair that the * static analysis can use. */context_lock_struct(__context_bitlock) { };#define __bitlock(bitnum, addr) (struct __context_bitlock *)(bitnum + (addr))
/* * bit-based spin_lock() * * Don't use this unless you really need to: spin_lock() and spin_unlock() * are significantly faster. */static __always_inline void bit_spin_lock(int bitnum, unsigned long *addr) __acquires(__bitlock(bitnum, addr)){ /* * Assuming the lock is uncontended, this never enters * the body of the outer loop. If it is contended, then * within the inner loop a non-atomic test is used to * busywait with less bus contention for a good time to * attempt to acquire the lock bit. */ preempt_disable();#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) while (unlikely(test_and_set_bit_lock(bitnum, addr))) { preempt_enable(); do { cpu_relax(); } while (test_bit(bitnum, addr)); preempt_disable(); }#endif __acquire(__bitlock(bitnum, addr));}
/* * Return true if it was acquired */static __always_inline int bit_spin_trylock(int bitnum, unsigned long *addr) __cond_acquires(true, __bitlock(bitnum, addr)){ preempt_disable();#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) if (unlikely(test_and_set_bit_lock(bitnum, addr))) { preempt_enable(); return 0; }#endif __acquire(__bitlock(bitnum, addr)); return 1;}
/* * bit-based spin_unlock() */static __always_inline void bit_spin_unlock(int bitnum, unsigned long *addr) __releases(__bitlock(bitnum, addr)){#ifdef CONFIG_DEBUG_SPINLOCK BUG_ON(!test_bit(bitnum, addr));#endif#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) clear_bit_unlock(bitnum, addr);#endif preempt_enable(); __release(__bitlock(bitnum, addr));}
/* * bit-based spin_unlock() * non-atomic version, which can be used eg. if the bit lock itself is * protecting the rest of the flags in the word. */static __always_inline void __bit_spin_unlock(int bitnum, unsigned long *addr) __releases(__bitlock(bitnum, addr)){#ifdef CONFIG_DEBUG_SPINLOCK BUG_ON(!test_bit(bitnum, addr));#endif#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) __clear_bit_unlock(bitnum, addr);#endif preempt_enable(); __release(__bitlock(bitnum, addr));}
/* * Return true if the lock is held. */static inline int bit_spin_is_locked(int bitnum, unsigned long *addr){#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) return test_bit(bitnum, addr);#elif defined CONFIG_PREEMPT_COUNT return preempt_count();#else return 1;#endif}
#endif /* __LINUX_BIT_SPINLOCK_H */