| /* 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_raw: |
| * The raw types and 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_raw: |
| * The raw RT types and initializers |
| * 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/stringify.h> |
| #include <linux/bottom_half.h> |
| #include <linux/lockdep.h> |
| #include <asm/barrier.h> |
| #include <asm/mmiowb.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 __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, short inner); |
| |
| # define raw_spin_lock_init(lock) \ |
| do { \ |
| static struct lock_class_key __key; \ |
| \ |
| __raw_spin_lock_init((lock), #lock, &__key, LD_WAIT_SPIN); \ |
| } 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); |
| 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); |
| mmiowb_spin_lock(); |
| } |
| |
| static inline int do_raw_spin_trylock(raw_spinlock_t *lock) |
| { |
| int ret = arch_spin_trylock(&(lock)->raw_lock); |
| |
| if (ret) |
| mmiowb_spin_lock(); |
| |
| return ret; |
| } |
| |
| static inline void do_raw_spin_unlock(raw_spinlock_t *lock) __releases(lock) |
| { |
| mmiowb_spin_unlock(); |
| 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_PREEMPTION 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; }); \ |
| }) |
| |
| #ifndef CONFIG_PREEMPT_RT |
| /* Include rwlock functions for !RT */ |
| #include <linux/rwlock.h> |
| #endif |
| |
| /* |
| * 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 |
| |
| /* Non PREEMPT_RT kernel, map to raw spinlocks: */ |
| #ifndef CONFIG_PREEMPT_RT |
| |
| /* |
| * 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; |
| } |
| |
| #ifdef CONFIG_DEBUG_SPINLOCK |
| |
| # define spin_lock_init(lock) \ |
| do { \ |
| static struct lock_class_key __key; \ |
| \ |
| __raw_spin_lock_init(spinlock_check(lock), \ |
| #lock, &__key, LD_WAIT_CONFIG); \ |
| } while (0) |
| |
| #else |
| |
| # define spin_lock_init(_lock) \ |
| do { \ |
| spinlock_check(_lock); \ |
| *(_lock) = __SPIN_LOCK_UNLOCKED(_lock); \ |
| } while (0) |
| |
| #endif |
| |
| 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) |
| |
| #else /* !CONFIG_PREEMPT_RT */ |
| # include <linux/spinlock_rt.h> |
| #endif /* CONFIG_PREEMPT_RT */ |
| |
| /* |
| * 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 */ |