diff options
Diffstat (limited to 'include/linux/spinlock.h')
| -rw-r--r-- | include/linux/spinlock.h | 471 |
1 files changed, 471 insertions, 0 deletions
diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h new file mode 100644 index 000000000..e089157dc --- /dev/null +++ b/include/linux/spinlock.h @@ -0,0 +1,471 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __LINUX_SPINLOCK_H +#define __LINUX_SPINLOCK_H + +/* + * include/linux/spinlock.h - generic spinlock/rwlock declarations + * + * here's the role of the various spinlock/rwlock related include files: + * + * on SMP builds: + * + * asm/spinlock_types.h: contains the arch_spinlock_t/arch_rwlock_t and the + * initializers + * + * linux/spinlock_types.h: + * defines the generic type and initializers + * + * asm/spinlock.h: contains the arch_spin_*()/etc. lowlevel + * implementations, mostly inline assembly code + * + * (also included on UP-debug builds:) + * + * linux/spinlock_api_smp.h: + * contains the prototypes for the _spin_*() APIs. + * + * linux/spinlock.h: builds the final spin_*() APIs. + * + * on UP builds: + * + * linux/spinlock_type_up.h: + * contains the generic, simplified UP spinlock type. + * (which is an empty structure on non-debug builds) + * + * linux/spinlock_types.h: + * defines the generic type and initializers + * + * linux/spinlock_up.h: + * contains the arch_spin_*()/etc. version of UP + * builds. (which are NOPs on non-debug, non-preempt + * builds) + * + * (included on UP-non-debug builds:) + * + * linux/spinlock_api_up.h: + * builds the _spin_*() APIs. + * + * linux/spinlock.h: builds the final spin_*() APIs. + */ + +#include <linux/typecheck.h> +#include <linux/preempt.h> +#include <linux/linkage.h> +#include <linux/compiler.h> +#include <linux/irqflags.h> +#include <linux/thread_info.h> +#include <linux/kernel.h> +#include <linux/stringify.h> +#include <linux/bottom_half.h> +#include <asm/barrier.h> + + +/* + * Must define these before including other files, inline functions need them + */ +#define LOCK_SECTION_NAME ".text..lock."KBUILD_BASENAME + +#define LOCK_SECTION_START(extra) \ + ".subsection 1\n\t" \ + extra \ + ".ifndef " LOCK_SECTION_NAME "\n\t" \ + LOCK_SECTION_NAME ":\n\t" \ + ".endif\n" + +#define LOCK_SECTION_END \ + ".previous\n\t" + +#define __lockfunc __attribute__((section(".spinlock.text"))) + +/* + * Pull the arch_spinlock_t and arch_rwlock_t definitions: + */ +#include <linux/spinlock_types.h> + +/* + * Pull the arch_spin*() functions/declarations (UP-nondebug doesn't need them): + */ +#ifdef CONFIG_SMP +# include <asm/spinlock.h> +#else +# include <linux/spinlock_up.h> +#endif + +#ifdef CONFIG_DEBUG_SPINLOCK + extern void __raw_spin_lock_init(raw_spinlock_t *lock, const char *name, + struct lock_class_key *key); +# define raw_spin_lock_init(lock) \ +do { \ + static struct lock_class_key __key; \ + \ + __raw_spin_lock_init((lock), #lock, &__key); \ +} while (0) + +#else +# define raw_spin_lock_init(lock) \ + do { *(lock) = __RAW_SPIN_LOCK_UNLOCKED(lock); } while (0) +#endif + +#define raw_spin_is_locked(lock) arch_spin_is_locked(&(lock)->raw_lock) + +#ifdef arch_spin_is_contended +#define raw_spin_is_contended(lock) arch_spin_is_contended(&(lock)->raw_lock) +#else +#define raw_spin_is_contended(lock) (((void)(lock), 0)) +#endif /*arch_spin_is_contended*/ + +/* + * smp_mb__after_spinlock() provides the equivalent of a full memory barrier + * between program-order earlier lock acquisitions and program-order later + * memory accesses. + * + * This guarantees that the following two properties hold: + * + * 1) Given the snippet: + * + * { X = 0; Y = 0; } + * + * CPU0 CPU1 + * + * WRITE_ONCE(X, 1); WRITE_ONCE(Y, 1); + * spin_lock(S); smp_mb(); + * smp_mb__after_spinlock(); r1 = READ_ONCE(X); + * r0 = READ_ONCE(Y); + * spin_unlock(S); + * + * it is forbidden that CPU0 does not observe CPU1's store to Y (r0 = 0) + * and CPU1 does not observe CPU0's store to X (r1 = 0); see the comments + * preceding the call to smp_mb__after_spinlock() in __schedule() and in + * try_to_wake_up(). + * + * 2) Given the snippet: + * + * { X = 0; Y = 0; } + * + * CPU0 CPU1 CPU2 + * + * spin_lock(S); spin_lock(S); r1 = READ_ONCE(Y); + * WRITE_ONCE(X, 1); smp_mb__after_spinlock(); smp_rmb(); + * spin_unlock(S); r0 = READ_ONCE(X); r2 = READ_ONCE(X); + * WRITE_ONCE(Y, 1); + * spin_unlock(S); + * + * it is forbidden that CPU0's critical section executes before CPU1's + * critical section (r0 = 1), CPU2 observes CPU1's store to Y (r1 = 1) + * and CPU2 does not observe CPU0's store to X (r2 = 0); see the comments + * preceding the calls to smp_rmb() in try_to_wake_up() for similar + * snippets but "projected" onto two CPUs. + * + * Property (2) upgrades the lock to an RCsc lock. + * + * Since most load-store architectures implement ACQUIRE with an smp_mb() after + * the LL/SC loop, they need no further barriers. Similarly all our TSO + * architectures imply an smp_mb() for each atomic instruction and equally don't + * need more. + * + * Architectures that can implement ACQUIRE better need to take care. + */ +#ifndef smp_mb__after_spinlock +#define smp_mb__after_spinlock() do { } while (0) +#endif + +#ifdef CONFIG_DEBUG_SPINLOCK + extern void do_raw_spin_lock(raw_spinlock_t *lock) __acquires(lock); +#define do_raw_spin_lock_flags(lock, flags) do_raw_spin_lock(lock) + extern int do_raw_spin_trylock(raw_spinlock_t *lock); + extern void do_raw_spin_unlock(raw_spinlock_t *lock) __releases(lock); +#else +static inline void do_raw_spin_lock(raw_spinlock_t *lock) __acquires(lock) +{ + __acquire(lock); + arch_spin_lock(&lock->raw_lock); +} + +#ifndef arch_spin_lock_flags +#define arch_spin_lock_flags(lock, flags) arch_spin_lock(lock) +#endif + +static inline void +do_raw_spin_lock_flags(raw_spinlock_t *lock, unsigned long *flags) __acquires(lock) +{ + __acquire(lock); + arch_spin_lock_flags(&lock->raw_lock, *flags); +} + +static inline int do_raw_spin_trylock(raw_spinlock_t *lock) +{ + return arch_spin_trylock(&(lock)->raw_lock); +} + +static inline void do_raw_spin_unlock(raw_spinlock_t *lock) __releases(lock) +{ + arch_spin_unlock(&lock->raw_lock); + __release(lock); +} +#endif + +/* + * Define the various spin_lock methods. Note we define these + * regardless of whether CONFIG_SMP or CONFIG_PREEMPT are set. The + * various methods are defined as nops in the case they are not + * required. + */ +#define raw_spin_trylock(lock) __cond_lock(lock, _raw_spin_trylock(lock)) + +#define raw_spin_lock(lock) _raw_spin_lock(lock) + +#ifdef CONFIG_DEBUG_LOCK_ALLOC +# define raw_spin_lock_nested(lock, subclass) \ + _raw_spin_lock_nested(lock, subclass) + +# define raw_spin_lock_nest_lock(lock, nest_lock) \ + do { \ + typecheck(struct lockdep_map *, &(nest_lock)->dep_map);\ + _raw_spin_lock_nest_lock(lock, &(nest_lock)->dep_map); \ + } while (0) +#else +/* + * Always evaluate the 'subclass' argument to avoid that the compiler + * warns about set-but-not-used variables when building with + * CONFIG_DEBUG_LOCK_ALLOC=n and with W=1. + */ +# define raw_spin_lock_nested(lock, subclass) \ + _raw_spin_lock(((void)(subclass), (lock))) +# define raw_spin_lock_nest_lock(lock, nest_lock) _raw_spin_lock(lock) +#endif + +#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) + +#define raw_spin_lock_irqsave(lock, flags) \ + do { \ + typecheck(unsigned long, flags); \ + flags = _raw_spin_lock_irqsave(lock); \ + } while (0) + +#ifdef CONFIG_DEBUG_LOCK_ALLOC +#define raw_spin_lock_irqsave_nested(lock, flags, subclass) \ + do { \ + typecheck(unsigned long, flags); \ + flags = _raw_spin_lock_irqsave_nested(lock, subclass); \ + } while (0) +#else +#define raw_spin_lock_irqsave_nested(lock, flags, subclass) \ + do { \ + typecheck(unsigned long, flags); \ + flags = _raw_spin_lock_irqsave(lock); \ + } while (0) +#endif + +#else + +#define raw_spin_lock_irqsave(lock, flags) \ + do { \ + typecheck(unsigned long, flags); \ + _raw_spin_lock_irqsave(lock, flags); \ + } while (0) + +#define raw_spin_lock_irqsave_nested(lock, flags, subclass) \ + raw_spin_lock_irqsave(lock, flags) + +#endif + +#define raw_spin_lock_irq(lock) _raw_spin_lock_irq(lock) +#define raw_spin_lock_bh(lock) _raw_spin_lock_bh(lock) +#define raw_spin_unlock(lock) _raw_spin_unlock(lock) +#define raw_spin_unlock_irq(lock) _raw_spin_unlock_irq(lock) + +#define raw_spin_unlock_irqrestore(lock, flags) \ + do { \ + typecheck(unsigned long, flags); \ + _raw_spin_unlock_irqrestore(lock, flags); \ + } while (0) +#define raw_spin_unlock_bh(lock) _raw_spin_unlock_bh(lock) + +#define raw_spin_trylock_bh(lock) \ + __cond_lock(lock, _raw_spin_trylock_bh(lock)) + +#define raw_spin_trylock_irq(lock) \ +({ \ + local_irq_disable(); \ + raw_spin_trylock(lock) ? \ + 1 : ({ local_irq_enable(); 0; }); \ +}) + +#define raw_spin_trylock_irqsave(lock, flags) \ +({ \ + local_irq_save(flags); \ + raw_spin_trylock(lock) ? \ + 1 : ({ local_irq_restore(flags); 0; }); \ +}) + +/* Include rwlock functions */ +#include <linux/rwlock.h> + +/* + * Pull the _spin_*()/_read_*()/_write_*() functions/declarations: + */ +#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) +# include <linux/spinlock_api_smp.h> +#else +# include <linux/spinlock_api_up.h> +#endif + +/* + * Map the spin_lock functions to the raw variants for PREEMPT_RT=n + */ + +static __always_inline raw_spinlock_t *spinlock_check(spinlock_t *lock) +{ + return &lock->rlock; +} + +#define spin_lock_init(_lock) \ +do { \ + spinlock_check(_lock); \ + raw_spin_lock_init(&(_lock)->rlock); \ +} while (0) + +static __always_inline void spin_lock(spinlock_t *lock) +{ + raw_spin_lock(&lock->rlock); +} + +static __always_inline void spin_lock_bh(spinlock_t *lock) +{ + raw_spin_lock_bh(&lock->rlock); +} + +static __always_inline int spin_trylock(spinlock_t *lock) +{ + return raw_spin_trylock(&lock->rlock); +} + +#define spin_lock_nested(lock, subclass) \ +do { \ + raw_spin_lock_nested(spinlock_check(lock), subclass); \ +} while (0) + +#define spin_lock_nest_lock(lock, nest_lock) \ +do { \ + raw_spin_lock_nest_lock(spinlock_check(lock), nest_lock); \ +} while (0) + +static __always_inline void spin_lock_irq(spinlock_t *lock) +{ + raw_spin_lock_irq(&lock->rlock); +} + +#define spin_lock_irqsave(lock, flags) \ +do { \ + raw_spin_lock_irqsave(spinlock_check(lock), flags); \ +} while (0) + +#define spin_lock_irqsave_nested(lock, flags, subclass) \ +do { \ + raw_spin_lock_irqsave_nested(spinlock_check(lock), flags, subclass); \ +} while (0) + +static __always_inline void spin_unlock(spinlock_t *lock) +{ + raw_spin_unlock(&lock->rlock); +} + +static __always_inline void spin_unlock_bh(spinlock_t *lock) +{ + raw_spin_unlock_bh(&lock->rlock); +} + +static __always_inline void spin_unlock_irq(spinlock_t *lock) +{ + raw_spin_unlock_irq(&lock->rlock); +} + +static __always_inline void spin_unlock_irqrestore(spinlock_t *lock, unsigned long flags) +{ + raw_spin_unlock_irqrestore(&lock->rlock, flags); +} + +static __always_inline int spin_trylock_bh(spinlock_t *lock) +{ + return raw_spin_trylock_bh(&lock->rlock); +} + +static __always_inline int spin_trylock_irq(spinlock_t *lock) +{ + return raw_spin_trylock_irq(&lock->rlock); +} + +#define spin_trylock_irqsave(lock, flags) \ +({ \ + raw_spin_trylock_irqsave(spinlock_check(lock), flags); \ +}) + +/** + * spin_is_locked() - Check whether a spinlock is locked. + * @lock: Pointer to the spinlock. + * + * This function is NOT required to provide any memory ordering + * guarantees; it could be used for debugging purposes or, when + * additional synchronization is needed, accompanied with other + * constructs (memory barriers) enforcing the synchronization. + * + * Returns: 1 if @lock is locked, 0 otherwise. + * + * Note that the function only tells you that the spinlock is + * seen to be locked, not that it is locked on your CPU. + * + * Further, on CONFIG_SMP=n builds with CONFIG_DEBUG_SPINLOCK=n, + * the return value is always 0 (see include/linux/spinlock_up.h). + * Therefore you should not rely heavily on the return value. + */ +static __always_inline int spin_is_locked(spinlock_t *lock) +{ + return raw_spin_is_locked(&lock->rlock); +} + +static __always_inline int spin_is_contended(spinlock_t *lock) +{ + return raw_spin_is_contended(&lock->rlock); +} + +#define assert_spin_locked(lock) assert_raw_spin_locked(&(lock)->rlock) + +/* + * Pull the atomic_t declaration: + * (asm-mips/atomic.h needs above definitions) + */ +#include <linux/atomic.h> +/** + * atomic_dec_and_lock - lock on reaching reference count zero + * @atomic: the atomic counter + * @lock: the spinlock in question + * + * Decrements @atomic by 1. If the result is 0, returns true and locks + * @lock. Returns false for all other cases. + */ +extern int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock); +#define atomic_dec_and_lock(atomic, lock) \ + __cond_lock(lock, _atomic_dec_and_lock(atomic, lock)) + +extern int _atomic_dec_and_lock_irqsave(atomic_t *atomic, spinlock_t *lock, + unsigned long *flags); +#define atomic_dec_and_lock_irqsave(atomic, lock, flags) \ + __cond_lock(lock, _atomic_dec_and_lock_irqsave(atomic, lock, &(flags))) + +int __alloc_bucket_spinlocks(spinlock_t **locks, unsigned int *lock_mask, + size_t max_size, unsigned int cpu_mult, + gfp_t gfp, const char *name, + struct lock_class_key *key); + +#define alloc_bucket_spinlocks(locks, lock_mask, max_size, cpu_mult, gfp) \ + ({ \ + static struct lock_class_key key; \ + int ret; \ + \ + ret = __alloc_bucket_spinlocks(locks, lock_mask, max_size, \ + cpu_mult, gfp, #locks, &key); \ + ret; \ + }) + +void free_bucket_spinlocks(spinlock_t *locks); + +#endif /* __LINUX_SPINLOCK_H */ |