xref: /linux-6.15/include/linux/spinlock.h (revision 4f3865fb) 
1 #ifndef __LINUX_SPINLOCK_H
2 #define __LINUX_SPINLOCK_H
3 
4 /*
5  * include/linux/spinlock.h - generic spinlock/rwlock declarations
6  *
7  * here's the role of the various spinlock/rwlock related include files:
8  *
9  * on SMP builds:
10  *
11  *  asm/spinlock_types.h: contains the raw_spinlock_t/raw_rwlock_t and the
12  *                        initializers
13  *
14  *  linux/spinlock_types.h:
15  *                        defines the generic type and initializers
16  *
17  *  asm/spinlock.h:       contains the __raw_spin_*()/etc. lowlevel
18  *                        implementations, mostly inline assembly code
19  *
20  *   (also included on UP-debug builds:)
21  *
22  *  linux/spinlock_api_smp.h:
23  *                        contains the prototypes for the _spin_*() APIs.
24  *
25  *  linux/spinlock.h:     builds the final spin_*() APIs.
26  *
27  * on UP builds:
28  *
29  *  linux/spinlock_type_up.h:
30  *                        contains the generic, simplified UP spinlock type.
31  *                        (which is an empty structure on non-debug builds)
32  *
33  *  linux/spinlock_types.h:
34  *                        defines the generic type and initializers
35  *
36  *  linux/spinlock_up.h:
37  *                        contains the __raw_spin_*()/etc. version of UP
38  *                        builds. (which are NOPs on non-debug, non-preempt
39  *                        builds)
40  *
41  *   (included on UP-non-debug builds:)
42  *
43  *  linux/spinlock_api_up.h:
44  *                        builds the _spin_*() APIs.
45  *
46  *  linux/spinlock.h:     builds the final spin_*() APIs.
47  */
48 
49 #include <linux/preempt.h>
50 #include <linux/linkage.h>
51 #include <linux/compiler.h>
52 #include <linux/thread_info.h>
53 #include <linux/kernel.h>
54 #include <linux/stringify.h>
55 
56 #include <asm/system.h>
57 
58 /*
59  * Must define these before including other files, inline functions need them
60  */
61 #define LOCK_SECTION_NAME ".text.lock."KBUILD_BASENAME
62 
63 #define LOCK_SECTION_START(extra)               \
64         ".subsection 1\n\t"                     \
65         extra                                   \
66         ".ifndef " LOCK_SECTION_NAME "\n\t"     \
67         LOCK_SECTION_NAME ":\n\t"               \
68         ".endif\n"
69 
70 #define LOCK_SECTION_END                        \
71         ".previous\n\t"
72 
73 #define __lockfunc fastcall __attribute__((section(".spinlock.text")))
74 
75 /*
76  * Pull the raw_spinlock_t and raw_rwlock_t definitions:
77  */
78 #include <linux/spinlock_types.h>
79 
80 extern int __lockfunc generic__raw_read_trylock(raw_rwlock_t *lock);
81 
82 /*
83  * Pull the __raw*() functions/declarations (UP-nondebug doesnt need them):
84  */
85 #if defined(CONFIG_SMP)
86 # include <asm/spinlock.h>
87 #else
88 # include <linux/spinlock_up.h>
89 #endif
90 
91 #define spin_lock_init(lock)	do { *(lock) = SPIN_LOCK_UNLOCKED; } while (0)
92 #define rwlock_init(lock)	do { *(lock) = RW_LOCK_UNLOCKED; } while (0)
93 
94 #define spin_is_locked(lock)	__raw_spin_is_locked(&(lock)->raw_lock)
95 
96 /**
97  * spin_unlock_wait - wait until the spinlock gets unlocked
98  * @lock: the spinlock in question.
99  */
100 #define spin_unlock_wait(lock)	__raw_spin_unlock_wait(&(lock)->raw_lock)
101 
102 /*
103  * Pull the _spin_*()/_read_*()/_write_*() functions/declarations:
104  */
105 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
106 # include <linux/spinlock_api_smp.h>
107 #else
108 # include <linux/spinlock_api_up.h>
109 #endif
110 
111 #ifdef CONFIG_DEBUG_SPINLOCK
112  extern void _raw_spin_lock(spinlock_t *lock);
113 #define _raw_spin_lock_flags(lock, flags) _raw_spin_lock(lock)
114  extern int _raw_spin_trylock(spinlock_t *lock);
115  extern void _raw_spin_unlock(spinlock_t *lock);
116 
117  extern void _raw_read_lock(rwlock_t *lock);
118  extern int _raw_read_trylock(rwlock_t *lock);
119  extern void _raw_read_unlock(rwlock_t *lock);
120  extern void _raw_write_lock(rwlock_t *lock);
121  extern int _raw_write_trylock(rwlock_t *lock);
122  extern void _raw_write_unlock(rwlock_t *lock);
123 #else
124 # define _raw_spin_unlock(lock)		__raw_spin_unlock(&(lock)->raw_lock)
125 # define _raw_spin_trylock(lock)	__raw_spin_trylock(&(lock)->raw_lock)
126 # define _raw_spin_lock(lock)		__raw_spin_lock(&(lock)->raw_lock)
127 # define _raw_spin_lock_flags(lock, flags) \
128 		__raw_spin_lock_flags(&(lock)->raw_lock, *(flags))
129 # define _raw_read_lock(rwlock)		__raw_read_lock(&(rwlock)->raw_lock)
130 # define _raw_write_lock(rwlock)	__raw_write_lock(&(rwlock)->raw_lock)
131 # define _raw_read_unlock(rwlock)	__raw_read_unlock(&(rwlock)->raw_lock)
132 # define _raw_write_unlock(rwlock)	__raw_write_unlock(&(rwlock)->raw_lock)
133 # define _raw_read_trylock(rwlock)	__raw_read_trylock(&(rwlock)->raw_lock)
134 # define _raw_write_trylock(rwlock)	__raw_write_trylock(&(rwlock)->raw_lock)
135 #endif
136 
137 #define read_can_lock(rwlock)		__raw_read_can_lock(&(rwlock)->raw_lock)
138 #define write_can_lock(rwlock)		__raw_write_can_lock(&(rwlock)->raw_lock)
139 
140 /*
141  * Define the various spin_lock and rw_lock methods.  Note we define these
142  * regardless of whether CONFIG_SMP or CONFIG_PREEMPT are set. The various
143  * methods are defined as nops in the case they are not required.
144  */
145 #define spin_trylock(lock)		__cond_lock(_spin_trylock(lock))
146 #define read_trylock(lock)		__cond_lock(_read_trylock(lock))
147 #define write_trylock(lock)		__cond_lock(_write_trylock(lock))
148 
149 #define spin_lock(lock)			_spin_lock(lock)
150 #define write_lock(lock)		_write_lock(lock)
151 #define read_lock(lock)			_read_lock(lock)
152 
153 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
154 #define spin_lock_irqsave(lock, flags)	flags = _spin_lock_irqsave(lock)
155 #define read_lock_irqsave(lock, flags)	flags = _read_lock_irqsave(lock)
156 #define write_lock_irqsave(lock, flags)	flags = _write_lock_irqsave(lock)
157 #else
158 #define spin_lock_irqsave(lock, flags)	_spin_lock_irqsave(lock, flags)
159 #define read_lock_irqsave(lock, flags)	_read_lock_irqsave(lock, flags)
160 #define write_lock_irqsave(lock, flags)	_write_lock_irqsave(lock, flags)
161 #endif
162 
163 #define spin_lock_irq(lock)		_spin_lock_irq(lock)
164 #define spin_lock_bh(lock)		_spin_lock_bh(lock)
165 
166 #define read_lock_irq(lock)		_read_lock_irq(lock)
167 #define read_lock_bh(lock)		_read_lock_bh(lock)
168 
169 #define write_lock_irq(lock)		_write_lock_irq(lock)
170 #define write_lock_bh(lock)		_write_lock_bh(lock)
171 
172 /*
173  * We inline the unlock functions in the nondebug case:
174  */
175 #if defined(CONFIG_DEBUG_SPINLOCK) || defined(CONFIG_PREEMPT) || !defined(CONFIG_SMP)
176 # define spin_unlock(lock)		_spin_unlock(lock)
177 # define read_unlock(lock)		_read_unlock(lock)
178 # define write_unlock(lock)		_write_unlock(lock)
179 #else
180 # define spin_unlock(lock)		__raw_spin_unlock(&(lock)->raw_lock)
181 # define read_unlock(lock)		__raw_read_unlock(&(lock)->raw_lock)
182 # define write_unlock(lock)		__raw_write_unlock(&(lock)->raw_lock)
183 #endif
184 
185 #if defined(CONFIG_DEBUG_SPINLOCK) || defined(CONFIG_PREEMPT) || !defined(CONFIG_SMP)
186 # define spin_unlock_irq(lock)		_spin_unlock_irq(lock)
187 # define read_unlock_irq(lock)		_read_unlock_irq(lock)
188 # define write_unlock_irq(lock)		_write_unlock_irq(lock)
189 #else
190 # define spin_unlock_irq(lock) \
191     do { __raw_spin_unlock(&(lock)->raw_lock); local_irq_enable(); } while (0)
192 # define read_unlock_irq(lock) \
193     do { __raw_read_unlock(&(lock)->raw_lock); local_irq_enable(); } while (0)
194 # define write_unlock_irq(lock) \
195     do { __raw_write_unlock(&(lock)->raw_lock); local_irq_enable(); } while (0)
196 #endif
197 
198 #define spin_unlock_irqrestore(lock, flags) \
199 					_spin_unlock_irqrestore(lock, flags)
200 #define spin_unlock_bh(lock)		_spin_unlock_bh(lock)
201 
202 #define read_unlock_irqrestore(lock, flags) \
203 					_read_unlock_irqrestore(lock, flags)
204 #define read_unlock_bh(lock)		_read_unlock_bh(lock)
205 
206 #define write_unlock_irqrestore(lock, flags) \
207 					_write_unlock_irqrestore(lock, flags)
208 #define write_unlock_bh(lock)		_write_unlock_bh(lock)
209 
210 #define spin_trylock_bh(lock)		__cond_lock(_spin_trylock_bh(lock))
211 
212 #define spin_trylock_irq(lock) \
213 ({ \
214 	local_irq_disable(); \
215 	_spin_trylock(lock) ? \
216 	1 : ({ local_irq_enable(); 0;  }); \
217 })
218 
219 #define spin_trylock_irqsave(lock, flags) \
220 ({ \
221 	local_irq_save(flags); \
222 	_spin_trylock(lock) ? \
223 	1 : ({ local_irq_restore(flags); 0; }); \
224 })
225 
226 /*
227  * Pull the atomic_t declaration:
228  * (asm-mips/atomic.h needs above definitions)
229  */
230 #include <asm/atomic.h>
231 /**
232  * atomic_dec_and_lock - lock on reaching reference count zero
233  * @atomic: the atomic counter
234  * @lock: the spinlock in question
235  */
236 extern int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock);
237 #define atomic_dec_and_lock(atomic, lock) \
238 		__cond_lock(_atomic_dec_and_lock(atomic, lock))
239 
240 /**
241  * spin_can_lock - would spin_trylock() succeed?
242  * @lock: the spinlock in question.
243  */
244 #define spin_can_lock(lock)	(!spin_is_locked(lock))
245 
246 #endif /* __LINUX_SPINLOCK_H */
247