xref: /linux-6.15/include/linux/spinlock.h (revision 4e57b681) 
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/config.h>
50 #include <linux/preempt.h>
51 #include <linux/linkage.h>
52 #include <linux/compiler.h>
53 #include <linux/thread_info.h>
54 #include <linux/kernel.h>
55 #include <linux/stringify.h>
56 
57 #include <asm/system.h>
58 
59 /*
60  * Must define these before including other files, inline functions need them
61  */
62 #define LOCK_SECTION_NAME                       \
63         ".text.lock." __stringify(KBUILD_BASENAME)
64 
65 #define LOCK_SECTION_START(extra)               \
66         ".subsection 1\n\t"                     \
67         extra                                   \
68         ".ifndef " LOCK_SECTION_NAME "\n\t"     \
69         LOCK_SECTION_NAME ":\n\t"               \
70         ".endif\n"
71 
72 #define LOCK_SECTION_END                        \
73         ".previous\n\t"
74 
75 #define __lockfunc fastcall __attribute__((section(".spinlock.text")))
76 
77 /*
78  * Pull the raw_spinlock_t and raw_rwlock_t definitions:
79  */
80 #include <linux/spinlock_types.h>
81 
82 extern int __lockfunc generic__raw_read_trylock(raw_rwlock_t *lock);
83 
84 /*
85  * Pull the __raw*() functions/declarations (UP-nondebug doesnt need them):
86  */
87 #if defined(CONFIG_SMP)
88 # include <asm/spinlock.h>
89 #else
90 # include <linux/spinlock_up.h>
91 #endif
92 
93 #define spin_lock_init(lock)	do { *(lock) = SPIN_LOCK_UNLOCKED; } while (0)
94 #define rwlock_init(lock)	do { *(lock) = RW_LOCK_UNLOCKED; } while (0)
95 
96 #define spin_is_locked(lock)	__raw_spin_is_locked(&(lock)->raw_lock)
97 
98 /**
99  * spin_unlock_wait - wait until the spinlock gets unlocked
100  * @lock: the spinlock in question.
101  */
102 #define spin_unlock_wait(lock)	__raw_spin_unlock_wait(&(lock)->raw_lock)
103 
104 /*
105  * Pull the _spin_*()/_read_*()/_write_*() functions/declarations:
106  */
107 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
108 # include <linux/spinlock_api_smp.h>
109 #else
110 # include <linux/spinlock_api_up.h>
111 #endif
112 
113 #ifdef CONFIG_DEBUG_SPINLOCK
114  extern void _raw_spin_lock(spinlock_t *lock);
115 #define _raw_spin_lock_flags(lock, flags) _raw_spin_lock(lock)
116  extern int _raw_spin_trylock(spinlock_t *lock);
117  extern void _raw_spin_unlock(spinlock_t *lock);
118 
119  extern void _raw_read_lock(rwlock_t *lock);
120  extern int _raw_read_trylock(rwlock_t *lock);
121  extern void _raw_read_unlock(rwlock_t *lock);
122  extern void _raw_write_lock(rwlock_t *lock);
123  extern int _raw_write_trylock(rwlock_t *lock);
124  extern void _raw_write_unlock(rwlock_t *lock);
125 #else
126 # define _raw_spin_unlock(lock)		__raw_spin_unlock(&(lock)->raw_lock)
127 # define _raw_spin_trylock(lock)	__raw_spin_trylock(&(lock)->raw_lock)
128 # define _raw_spin_lock(lock)		__raw_spin_lock(&(lock)->raw_lock)
129 # define _raw_spin_lock_flags(lock, flags) \
130 		__raw_spin_lock_flags(&(lock)->raw_lock, *(flags))
131 # define _raw_read_lock(rwlock)		__raw_read_lock(&(rwlock)->raw_lock)
132 # define _raw_write_lock(rwlock)	__raw_write_lock(&(rwlock)->raw_lock)
133 # define _raw_read_unlock(rwlock)	__raw_read_unlock(&(rwlock)->raw_lock)
134 # define _raw_write_unlock(rwlock)	__raw_write_unlock(&(rwlock)->raw_lock)
135 # define _raw_read_trylock(rwlock)	__raw_read_trylock(&(rwlock)->raw_lock)
136 # define _raw_write_trylock(rwlock)	__raw_write_trylock(&(rwlock)->raw_lock)
137 #endif
138 
139 #define read_can_lock(rwlock)		__raw_read_can_lock(&(rwlock)->raw_lock)
140 #define write_can_lock(rwlock)		__raw_write_can_lock(&(rwlock)->raw_lock)
141 
142 /*
143  * Define the various spin_lock and rw_lock methods.  Note we define these
144  * regardless of whether CONFIG_SMP or CONFIG_PREEMPT are set. The various
145  * methods are defined as nops in the case they are not required.
146  */
147 #define spin_trylock(lock)		__cond_lock(_spin_trylock(lock))
148 #define read_trylock(lock)		__cond_lock(_read_trylock(lock))
149 #define write_trylock(lock)		__cond_lock(_write_trylock(lock))
150 
151 #define spin_lock(lock)			_spin_lock(lock)
152 #define write_lock(lock)		_write_lock(lock)
153 #define read_lock(lock)			_read_lock(lock)
154 
155 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
156 #define spin_lock_irqsave(lock, flags)	flags = _spin_lock_irqsave(lock)
157 #define read_lock_irqsave(lock, flags)	flags = _read_lock_irqsave(lock)
158 #define write_lock_irqsave(lock, flags)	flags = _write_lock_irqsave(lock)
159 #else
160 #define spin_lock_irqsave(lock, flags)	_spin_lock_irqsave(lock, flags)
161 #define read_lock_irqsave(lock, flags)	_read_lock_irqsave(lock, flags)
162 #define write_lock_irqsave(lock, flags)	_write_lock_irqsave(lock, flags)
163 #endif
164 
165 #define spin_lock_irq(lock)		_spin_lock_irq(lock)
166 #define spin_lock_bh(lock)		_spin_lock_bh(lock)
167 
168 #define read_lock_irq(lock)		_read_lock_irq(lock)
169 #define read_lock_bh(lock)		_read_lock_bh(lock)
170 
171 #define write_lock_irq(lock)		_write_lock_irq(lock)
172 #define write_lock_bh(lock)		_write_lock_bh(lock)
173 
174 /*
175  * We inline the unlock functions in the nondebug case:
176  */
177 #if defined(CONFIG_DEBUG_SPINLOCK) || defined(CONFIG_PREEMPT) || !defined(CONFIG_SMP)
178 # define spin_unlock(lock)		_spin_unlock(lock)
179 # define read_unlock(lock)		_read_unlock(lock)
180 # define write_unlock(lock)		_write_unlock(lock)
181 #else
182 # define spin_unlock(lock)		__raw_spin_unlock(&(lock)->raw_lock)
183 # define read_unlock(lock)		__raw_read_unlock(&(lock)->raw_lock)
184 # define write_unlock(lock)		__raw_write_unlock(&(lock)->raw_lock)
185 #endif
186 
187 #if defined(CONFIG_DEBUG_SPINLOCK) || defined(CONFIG_PREEMPT) || !defined(CONFIG_SMP)
188 # define spin_unlock_irq(lock)		_spin_unlock_irq(lock)
189 # define read_unlock_irq(lock)		_read_unlock_irq(lock)
190 # define write_unlock_irq(lock)		_write_unlock_irq(lock)
191 #else
192 # define spin_unlock_irq(lock) \
193     do { __raw_spin_unlock(&(lock)->raw_lock); local_irq_enable(); } while (0)
194 # define read_unlock_irq(lock) \
195     do { __raw_read_unlock(&(lock)->raw_lock); local_irq_enable(); } while (0)
196 # define write_unlock_irq(lock) \
197     do { __raw_write_unlock(&(lock)->raw_lock); local_irq_enable(); } while (0)
198 #endif
199 
200 #define spin_unlock_irqrestore(lock, flags) \
201 					_spin_unlock_irqrestore(lock, flags)
202 #define spin_unlock_bh(lock)		_spin_unlock_bh(lock)
203 
204 #define read_unlock_irqrestore(lock, flags) \
205 					_read_unlock_irqrestore(lock, flags)
206 #define read_unlock_bh(lock)		_read_unlock_bh(lock)
207 
208 #define write_unlock_irqrestore(lock, flags) \
209 					_write_unlock_irqrestore(lock, flags)
210 #define write_unlock_bh(lock)		_write_unlock_bh(lock)
211 
212 #define spin_trylock_bh(lock)		__cond_lock(_spin_trylock_bh(lock))
213 
214 #define spin_trylock_irq(lock) \
215 ({ \
216 	local_irq_disable(); \
217 	_spin_trylock(lock) ? \
218 	1 : ({ local_irq_enable(); 0;  }); \
219 })
220 
221 #define spin_trylock_irqsave(lock, flags) \
222 ({ \
223 	local_irq_save(flags); \
224 	_spin_trylock(lock) ? \
225 	1 : ({ local_irq_restore(flags); 0; }); \
226 })
227 
228 /*
229  * Pull the atomic_t declaration:
230  * (asm-mips/atomic.h needs above definitions)
231  */
232 #include <asm/atomic.h>
233 /**
234  * atomic_dec_and_lock - lock on reaching reference count zero
235  * @atomic: the atomic counter
236  * @lock: the spinlock in question
237  */
238 extern int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock);
239 #define atomic_dec_and_lock(atomic, lock) \
240 		__cond_lock(_atomic_dec_and_lock(atomic, lock))
241 
242 /**
243  * spin_can_lock - would spin_trylock() succeed?
244  * @lock: the spinlock in question.
245  */
246 #define spin_can_lock(lock)	(!spin_is_locked(lock))
247 
248 #endif /* __LINUX_SPINLOCK_H */
249