xref: /linux-6.15/include/linux/mmap_lock.h (revision 43b3dfdd) 
1 #ifndef _LINUX_MMAP_LOCK_H
2 #define _LINUX_MMAP_LOCK_H
3 
4 #include <linux/lockdep.h>
5 #include <linux/mm_types.h>
6 #include <linux/mmdebug.h>
7 #include <linux/rwsem.h>
8 #include <linux/tracepoint-defs.h>
9 #include <linux/types.h>
10 
11 #define MMAP_LOCK_INITIALIZER(name) \
12 	.mmap_lock = __RWSEM_INITIALIZER((name).mmap_lock),
13 
14 DECLARE_TRACEPOINT(mmap_lock_start_locking);
15 DECLARE_TRACEPOINT(mmap_lock_acquire_returned);
16 DECLARE_TRACEPOINT(mmap_lock_released);
17 
18 #ifdef CONFIG_TRACING
19 
20 void __mmap_lock_do_trace_start_locking(struct mm_struct *mm, bool write);
21 void __mmap_lock_do_trace_acquire_returned(struct mm_struct *mm, bool write,
22 					   bool success);
23 void __mmap_lock_do_trace_released(struct mm_struct *mm, bool write);
24 
25 static inline void __mmap_lock_trace_start_locking(struct mm_struct *mm,
26 						   bool write)
27 {
28 	if (tracepoint_enabled(mmap_lock_start_locking))
29 		__mmap_lock_do_trace_start_locking(mm, write);
30 }
31 
32 static inline void __mmap_lock_trace_acquire_returned(struct mm_struct *mm,
33 						      bool write, bool success)
34 {
35 	if (tracepoint_enabled(mmap_lock_acquire_returned))
36 		__mmap_lock_do_trace_acquire_returned(mm, write, success);
37 }
38 
39 static inline void __mmap_lock_trace_released(struct mm_struct *mm, bool write)
40 {
41 	if (tracepoint_enabled(mmap_lock_released))
42 		__mmap_lock_do_trace_released(mm, write);
43 }
44 
45 #else /* !CONFIG_TRACING */
46 
47 static inline void __mmap_lock_trace_start_locking(struct mm_struct *mm,
48 						   bool write)
49 {
50 }
51 
52 static inline void __mmap_lock_trace_acquire_returned(struct mm_struct *mm,
53 						      bool write, bool success)
54 {
55 }
56 
57 static inline void __mmap_lock_trace_released(struct mm_struct *mm, bool write)
58 {
59 }
60 
61 #endif /* CONFIG_TRACING */
62 
63 static inline void mmap_assert_locked(struct mm_struct *mm)
64 {
65 	lockdep_assert_held(&mm->mmap_lock);
66 	VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_lock), mm);
67 }
68 
69 static inline void mmap_assert_write_locked(struct mm_struct *mm)
70 {
71 	lockdep_assert_held_write(&mm->mmap_lock);
72 	VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_lock), mm);
73 }
74 
75 #ifdef CONFIG_PER_VMA_LOCK
76 static inline void vma_end_write_all(struct mm_struct *mm)
77 {
78 	mmap_assert_write_locked(mm);
79 	/*
80 	 * Nobody can concurrently modify mm->mm_lock_seq due to exclusive
81 	 * mmap_lock being held.
82 	 * We need RELEASE semantics here to ensure that preceding stores into
83 	 * the VMA take effect before we unlock it with this store.
84 	 * Pairs with ACQUIRE semantics in vma_start_read().
85 	 */
86 	smp_store_release(&mm->mm_lock_seq, mm->mm_lock_seq + 1);
87 }
88 #else
89 static inline void vma_end_write_all(struct mm_struct *mm) {}
90 #endif
91 
92 static inline void mmap_init_lock(struct mm_struct *mm)
93 {
94 	init_rwsem(&mm->mmap_lock);
95 }
96 
97 static inline void mmap_write_lock(struct mm_struct *mm)
98 {
99 	__mmap_lock_trace_start_locking(mm, true);
100 	down_write(&mm->mmap_lock);
101 	__mmap_lock_trace_acquire_returned(mm, true, true);
102 }
103 
104 static inline void mmap_write_lock_nested(struct mm_struct *mm, int subclass)
105 {
106 	__mmap_lock_trace_start_locking(mm, true);
107 	down_write_nested(&mm->mmap_lock, subclass);
108 	__mmap_lock_trace_acquire_returned(mm, true, true);
109 }
110 
111 static inline int mmap_write_lock_killable(struct mm_struct *mm)
112 {
113 	int ret;
114 
115 	__mmap_lock_trace_start_locking(mm, true);
116 	ret = down_write_killable(&mm->mmap_lock);
117 	__mmap_lock_trace_acquire_returned(mm, true, ret == 0);
118 	return ret;
119 }
120 
121 static inline void mmap_write_unlock(struct mm_struct *mm)
122 {
123 	__mmap_lock_trace_released(mm, true);
124 	vma_end_write_all(mm);
125 	up_write(&mm->mmap_lock);
126 }
127 
128 static inline void mmap_write_downgrade(struct mm_struct *mm)
129 {
130 	__mmap_lock_trace_acquire_returned(mm, false, true);
131 	vma_end_write_all(mm);
132 	downgrade_write(&mm->mmap_lock);
133 }
134 
135 static inline void mmap_read_lock(struct mm_struct *mm)
136 {
137 	__mmap_lock_trace_start_locking(mm, false);
138 	down_read(&mm->mmap_lock);
139 	__mmap_lock_trace_acquire_returned(mm, false, true);
140 }
141 
142 static inline int mmap_read_lock_killable(struct mm_struct *mm)
143 {
144 	int ret;
145 
146 	__mmap_lock_trace_start_locking(mm, false);
147 	ret = down_read_killable(&mm->mmap_lock);
148 	__mmap_lock_trace_acquire_returned(mm, false, ret == 0);
149 	return ret;
150 }
151 
152 static inline bool mmap_read_trylock(struct mm_struct *mm)
153 {
154 	bool ret;
155 
156 	__mmap_lock_trace_start_locking(mm, false);
157 	ret = down_read_trylock(&mm->mmap_lock) != 0;
158 	__mmap_lock_trace_acquire_returned(mm, false, ret);
159 	return ret;
160 }
161 
162 static inline void mmap_read_unlock(struct mm_struct *mm)
163 {
164 	__mmap_lock_trace_released(mm, false);
165 	up_read(&mm->mmap_lock);
166 }
167 
168 static inline void mmap_read_unlock_non_owner(struct mm_struct *mm)
169 {
170 	__mmap_lock_trace_released(mm, false);
171 	up_read_non_owner(&mm->mmap_lock);
172 }
173 
174 static inline int mmap_lock_is_contended(struct mm_struct *mm)
175 {
176 	return rwsem_is_contended(&mm->mmap_lock);
177 }
178 
179 #endif /* _LINUX_MMAP_LOCK_H */
180