1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef __LINUX_SPINLOCK_H
3 #define __LINUX_SPINLOCK_H
6 * include/linux/spinlock.h - generic spinlock/rwlock declarations
8 * here's the role of the various spinlock/rwlock related include files:
12 * asm/spinlock_types.h: contains the arch_spinlock_t/arch_rwlock_t and the
15 * linux/spinlock_types.h:
16 * defines the generic type and initializers
18 * asm/spinlock.h: contains the arch_spin_*()/etc. lowlevel
19 * implementations, mostly inline assembly code
21 * (also included on UP-debug builds:)
23 * linux/spinlock_api_smp.h:
24 * contains the prototypes for the _spin_*() APIs.
26 * linux/spinlock.h: builds the final spin_*() APIs.
30 * linux/spinlock_type_up.h:
31 * contains the generic, simplified UP spinlock type.
32 * (which is an empty structure on non-debug builds)
34 * linux/spinlock_types.h:
35 * defines the generic type and initializers
37 * linux/spinlock_up.h:
38 * contains the arch_spin_*()/etc. version of UP
39 * builds. (which are NOPs on non-debug, non-preempt
42 * (included on UP-non-debug builds:)
44 * linux/spinlock_api_up.h:
45 * builds the _spin_*() APIs.
47 * linux/spinlock.h: builds the final spin_*() APIs.
50 #include <linux/typecheck.h>
51 #include <linux/preempt.h>
52 #include <linux/linkage.h>
53 #include <linux/compiler.h>
54 #include <linux/irqflags.h>
55 #include <linux/thread_info.h>
56 #include <linux/kernel.h>
57 #include <linux/stringify.h>
58 #include <linux/bottom_half.h>
59 #include <asm/barrier.h>
63 * Must define these before including other files, inline functions need them
65 #define LOCK_SECTION_NAME ".text..lock."KBUILD_BASENAME
67 #define LOCK_SECTION_START(extra) \
70 ".ifndef " LOCK_SECTION_NAME "\n\t" \
71 LOCK_SECTION_NAME ":\n\t" \
74 #define LOCK_SECTION_END \
77 #define __lockfunc __attribute__((section(".spinlock.text")))
80 * Pull the arch_spinlock_t and arch_rwlock_t definitions:
82 #include <linux/spinlock_types.h>
85 * Pull the arch_spin*() functions/declarations (UP-nondebug doesn't need them):
88 # include <asm/spinlock.h>
90 # include <linux/spinlock_up.h>
93 #ifdef CONFIG_DEBUG_SPINLOCK
94 extern void __raw_spin_lock_init(raw_spinlock_t *lock, const char *name,
95 struct lock_class_key *key);
96 # define raw_spin_lock_init(lock) \
98 static struct lock_class_key __key; \
100 __raw_spin_lock_init((lock), #lock, &__key); \
104 # define raw_spin_lock_init(lock) \
105 do { *(lock) = __RAW_SPIN_LOCK_UNLOCKED(lock); } while (0)
108 #define raw_spin_is_locked(lock) arch_spin_is_locked(&(lock)->raw_lock)
110 #ifdef CONFIG_GENERIC_LOCKBREAK
111 #define raw_spin_is_contended(lock) ((lock)->break_lock)
114 #ifdef arch_spin_is_contended
115 #define raw_spin_is_contended(lock) arch_spin_is_contended(&(lock)->raw_lock)
117 #define raw_spin_is_contended(lock) (((void)(lock), 0))
118 #endif /*arch_spin_is_contended*/
122 * This barrier must provide two things:
124 * - it must guarantee a STORE before the spin_lock() is ordered against a
125 * LOAD after it, see the comments at its two usage sites.
127 * - it must ensure the critical section is RCsc.
129 * The latter is important for cases where we observe values written by other
130 * CPUs in spin-loops, without barriers, while being subject to scheduling.
143 * without transitivity it could be that CPU1 observes X!=0 breaks the loop,
144 * we get migrated and CPU2 sees X==0.
146 * Since most load-store architectures implement ACQUIRE with an smp_mb() after
147 * the LL/SC loop, they need no further barriers. Similarly all our TSO
148 * architectures imply an smp_mb() for each atomic instruction and equally don't
151 * Architectures that can implement ACQUIRE better need to take care.
153 #ifndef smp_mb__after_spinlock
154 #define smp_mb__after_spinlock() do { } while (0)
157 #ifdef CONFIG_DEBUG_SPINLOCK
158 extern void do_raw_spin_lock(raw_spinlock_t *lock) __acquires(lock);
159 #define do_raw_spin_lock_flags(lock, flags) do_raw_spin_lock(lock)
160 extern int do_raw_spin_trylock(raw_spinlock_t *lock);
161 extern void do_raw_spin_unlock(raw_spinlock_t *lock) __releases(lock);
163 static inline void do_raw_spin_lock(raw_spinlock_t *lock) __acquires(lock)
166 arch_spin_lock(&lock->raw_lock);
170 do_raw_spin_lock_flags(raw_spinlock_t *lock, unsigned long *flags) __acquires(lock)
173 arch_spin_lock_flags(&lock->raw_lock, *flags);
176 static inline int do_raw_spin_trylock(raw_spinlock_t *lock)
178 return arch_spin_trylock(&(lock)->raw_lock);
181 static inline void do_raw_spin_unlock(raw_spinlock_t *lock) __releases(lock)
183 arch_spin_unlock(&lock->raw_lock);
189 * Define the various spin_lock methods. Note we define these
190 * regardless of whether CONFIG_SMP or CONFIG_PREEMPT are set. The
191 * various methods are defined as nops in the case they are not
194 #define raw_spin_trylock(lock) __cond_lock(lock, _raw_spin_trylock(lock))
196 #define raw_spin_lock(lock) _raw_spin_lock(lock)
198 #ifdef CONFIG_DEBUG_LOCK_ALLOC
199 # define raw_spin_lock_nested(lock, subclass) \
200 _raw_spin_lock_nested(lock, subclass)
202 # define raw_spin_lock_nest_lock(lock, nest_lock) \
204 typecheck(struct lockdep_map *, &(nest_lock)->dep_map);\
205 _raw_spin_lock_nest_lock(lock, &(nest_lock)->dep_map); \
209 * Always evaluate the 'subclass' argument to avoid that the compiler
210 * warns about set-but-not-used variables when building with
211 * CONFIG_DEBUG_LOCK_ALLOC=n and with W=1.
213 # define raw_spin_lock_nested(lock, subclass) \
214 _raw_spin_lock(((void)(subclass), (lock)))
215 # define raw_spin_lock_nest_lock(lock, nest_lock) _raw_spin_lock(lock)
218 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
220 #define raw_spin_lock_irqsave(lock, flags) \
222 typecheck(unsigned long, flags); \
223 flags = _raw_spin_lock_irqsave(lock); \
226 #ifdef CONFIG_DEBUG_LOCK_ALLOC
227 #define raw_spin_lock_irqsave_nested(lock, flags, subclass) \
229 typecheck(unsigned long, flags); \
230 flags = _raw_spin_lock_irqsave_nested(lock, subclass); \
233 #define raw_spin_lock_irqsave_nested(lock, flags, subclass) \
235 typecheck(unsigned long, flags); \
236 flags = _raw_spin_lock_irqsave(lock); \
242 #define raw_spin_lock_irqsave(lock, flags) \
244 typecheck(unsigned long, flags); \
245 _raw_spin_lock_irqsave(lock, flags); \
248 #define raw_spin_lock_irqsave_nested(lock, flags, subclass) \
249 raw_spin_lock_irqsave(lock, flags)
253 #define raw_spin_lock_irq(lock) _raw_spin_lock_irq(lock)
254 #define raw_spin_lock_bh(lock) _raw_spin_lock_bh(lock)
255 #define raw_spin_unlock(lock) _raw_spin_unlock(lock)
256 #define raw_spin_unlock_irq(lock) _raw_spin_unlock_irq(lock)
258 #define raw_spin_unlock_irqrestore(lock, flags) \
260 typecheck(unsigned long, flags); \
261 _raw_spin_unlock_irqrestore(lock, flags); \
263 #define raw_spin_unlock_bh(lock) _raw_spin_unlock_bh(lock)
265 #define raw_spin_trylock_bh(lock) \
266 __cond_lock(lock, _raw_spin_trylock_bh(lock))
268 #define raw_spin_trylock_irq(lock) \
270 local_irq_disable(); \
271 raw_spin_trylock(lock) ? \
272 1 : ({ local_irq_enable(); 0; }); \
275 #define raw_spin_trylock_irqsave(lock, flags) \
277 local_irq_save(flags); \
278 raw_spin_trylock(lock) ? \
279 1 : ({ local_irq_restore(flags); 0; }); \
283 * raw_spin_can_lock - would raw_spin_trylock() succeed?
284 * @lock: the spinlock in question.
286 #define raw_spin_can_lock(lock) (!raw_spin_is_locked(lock))
288 /* Include rwlock functions */
289 #include <linux/rwlock.h>
292 * Pull the _spin_*()/_read_*()/_write_*() functions/declarations:
294 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
295 # include <linux/spinlock_api_smp.h>
297 # include <linux/spinlock_api_up.h>
301 * Map the spin_lock functions to the raw variants for PREEMPT_RT=n
304 static __always_inline raw_spinlock_t *spinlock_check(spinlock_t *lock)
309 #define spin_lock_init(_lock) \
311 spinlock_check(_lock); \
312 raw_spin_lock_init(&(_lock)->rlock); \
315 static __always_inline void spin_lock(spinlock_t *lock)
317 raw_spin_lock(&lock->rlock);
320 static __always_inline void spin_lock_bh(spinlock_t *lock)
322 raw_spin_lock_bh(&lock->rlock);
325 static __always_inline int spin_trylock(spinlock_t *lock)
327 return raw_spin_trylock(&lock->rlock);
330 #define spin_lock_nested(lock, subclass) \
332 raw_spin_lock_nested(spinlock_check(lock), subclass); \
335 #define spin_lock_nest_lock(lock, nest_lock) \
337 raw_spin_lock_nest_lock(spinlock_check(lock), nest_lock); \
340 static __always_inline void spin_lock_irq(spinlock_t *lock)
342 raw_spin_lock_irq(&lock->rlock);
345 #define spin_lock_irqsave(lock, flags) \
347 raw_spin_lock_irqsave(spinlock_check(lock), flags); \
350 #define spin_lock_irqsave_nested(lock, flags, subclass) \
352 raw_spin_lock_irqsave_nested(spinlock_check(lock), flags, subclass); \
355 static __always_inline void spin_unlock(spinlock_t *lock)
357 raw_spin_unlock(&lock->rlock);
360 static __always_inline void spin_unlock_bh(spinlock_t *lock)
362 raw_spin_unlock_bh(&lock->rlock);
365 static __always_inline void spin_unlock_irq(spinlock_t *lock)
367 raw_spin_unlock_irq(&lock->rlock);
370 static __always_inline void spin_unlock_irqrestore(spinlock_t *lock, unsigned long flags)
372 raw_spin_unlock_irqrestore(&lock->rlock, flags);
375 static __always_inline int spin_trylock_bh(spinlock_t *lock)
377 return raw_spin_trylock_bh(&lock->rlock);
380 static __always_inline int spin_trylock_irq(spinlock_t *lock)
382 return raw_spin_trylock_irq(&lock->rlock);
385 #define spin_trylock_irqsave(lock, flags) \
387 raw_spin_trylock_irqsave(spinlock_check(lock), flags); \
390 static __always_inline int spin_is_locked(spinlock_t *lock)
392 return raw_spin_is_locked(&lock->rlock);
395 static __always_inline int spin_is_contended(spinlock_t *lock)
397 return raw_spin_is_contended(&lock->rlock);
400 static __always_inline int spin_can_lock(spinlock_t *lock)
402 return raw_spin_can_lock(&lock->rlock);
405 #define assert_spin_locked(lock) assert_raw_spin_locked(&(lock)->rlock)
408 * Pull the atomic_t declaration:
409 * (asm-mips/atomic.h needs above definitions)
411 #include <linux/atomic.h>
413 * atomic_dec_and_lock - lock on reaching reference count zero
414 * @atomic: the atomic counter
415 * @lock: the spinlock in question
417 * Decrements @atomic by 1. If the result is 0, returns true and locks
418 * @lock. Returns false for all other cases.
420 extern int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock);
421 #define atomic_dec_and_lock(atomic, lock) \
422 __cond_lock(lock, _atomic_dec_and_lock(atomic, lock))
424 #endif /* __LINUX_SPINLOCK_H */