xref: /linux/include/linux/mmap_lock.h (revision ba168b52)
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 
__mmap_lock_trace_start_locking(struct mm_struct * mm,bool write)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 
__mmap_lock_trace_acquire_returned(struct mm_struct * mm,bool write,bool success)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 
__mmap_lock_trace_released(struct mm_struct * mm,bool write)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 
__mmap_lock_trace_start_locking(struct mm_struct * mm,bool write)47 static inline void __mmap_lock_trace_start_locking(struct mm_struct *mm,
48 						   bool write)
49 {
50 }
51 
__mmap_lock_trace_acquire_returned(struct mm_struct * mm,bool write,bool success)52 static inline void __mmap_lock_trace_acquire_returned(struct mm_struct *mm,
53 						      bool write, bool success)
54 {
55 }
56 
__mmap_lock_trace_released(struct mm_struct * mm,bool write)57 static inline void __mmap_lock_trace_released(struct mm_struct *mm, bool write)
58 {
59 }
60 
61 #endif /* CONFIG_TRACING */
62 
mmap_assert_locked(const struct mm_struct * mm)63 static inline void mmap_assert_locked(const struct mm_struct *mm)
64 {
65 	rwsem_assert_held(&mm->mmap_lock);
66 }
67 
mmap_assert_write_locked(const struct mm_struct * mm)68 static inline void mmap_assert_write_locked(const struct mm_struct *mm)
69 {
70 	rwsem_assert_held_write(&mm->mmap_lock);
71 }
72 
73 #ifdef CONFIG_PER_VMA_LOCK
74 /*
75  * Drop all currently-held per-VMA locks.
76  * This is called from the mmap_lock implementation directly before releasing
77  * a write-locked mmap_lock (or downgrading it to read-locked).
78  * This should normally NOT be called manually from other places.
79  * If you want to call this manually anyway, keep in mind that this will release
80  * *all* VMA write locks, including ones from further up the stack.
81  */
vma_end_write_all(struct mm_struct * mm)82 static inline void vma_end_write_all(struct mm_struct *mm)
83 {
84 	mmap_assert_write_locked(mm);
85 	/*
86 	 * Nobody can concurrently modify mm->mm_lock_seq due to exclusive
87 	 * mmap_lock being held.
88 	 * We need RELEASE semantics here to ensure that preceding stores into
89 	 * the VMA take effect before we unlock it with this store.
90 	 * Pairs with ACQUIRE semantics in vma_start_read().
91 	 */
92 	smp_store_release(&mm->mm_lock_seq, mm->mm_lock_seq + 1);
93 }
94 #else
vma_end_write_all(struct mm_struct * mm)95 static inline void vma_end_write_all(struct mm_struct *mm) {}
96 #endif
97 
mmap_init_lock(struct mm_struct * mm)98 static inline void mmap_init_lock(struct mm_struct *mm)
99 {
100 	init_rwsem(&mm->mmap_lock);
101 }
102 
mmap_write_lock(struct mm_struct * mm)103 static inline void mmap_write_lock(struct mm_struct *mm)
104 {
105 	__mmap_lock_trace_start_locking(mm, true);
106 	down_write(&mm->mmap_lock);
107 	__mmap_lock_trace_acquire_returned(mm, true, true);
108 }
109 
mmap_write_lock_nested(struct mm_struct * mm,int subclass)110 static inline void mmap_write_lock_nested(struct mm_struct *mm, int subclass)
111 {
112 	__mmap_lock_trace_start_locking(mm, true);
113 	down_write_nested(&mm->mmap_lock, subclass);
114 	__mmap_lock_trace_acquire_returned(mm, true, true);
115 }
116 
mmap_write_lock_killable(struct mm_struct * mm)117 static inline int mmap_write_lock_killable(struct mm_struct *mm)
118 {
119 	int ret;
120 
121 	__mmap_lock_trace_start_locking(mm, true);
122 	ret = down_write_killable(&mm->mmap_lock);
123 	__mmap_lock_trace_acquire_returned(mm, true, ret == 0);
124 	return ret;
125 }
126 
mmap_write_unlock(struct mm_struct * mm)127 static inline void mmap_write_unlock(struct mm_struct *mm)
128 {
129 	__mmap_lock_trace_released(mm, true);
130 	vma_end_write_all(mm);
131 	up_write(&mm->mmap_lock);
132 }
133 
mmap_write_downgrade(struct mm_struct * mm)134 static inline void mmap_write_downgrade(struct mm_struct *mm)
135 {
136 	__mmap_lock_trace_acquire_returned(mm, false, true);
137 	vma_end_write_all(mm);
138 	downgrade_write(&mm->mmap_lock);
139 }
140 
mmap_read_lock(struct mm_struct * mm)141 static inline void mmap_read_lock(struct mm_struct *mm)
142 {
143 	__mmap_lock_trace_start_locking(mm, false);
144 	down_read(&mm->mmap_lock);
145 	__mmap_lock_trace_acquire_returned(mm, false, true);
146 }
147 
mmap_read_lock_killable(struct mm_struct * mm)148 static inline int mmap_read_lock_killable(struct mm_struct *mm)
149 {
150 	int ret;
151 
152 	__mmap_lock_trace_start_locking(mm, false);
153 	ret = down_read_killable(&mm->mmap_lock);
154 	__mmap_lock_trace_acquire_returned(mm, false, ret == 0);
155 	return ret;
156 }
157 
mmap_read_trylock(struct mm_struct * mm)158 static inline bool mmap_read_trylock(struct mm_struct *mm)
159 {
160 	bool ret;
161 
162 	__mmap_lock_trace_start_locking(mm, false);
163 	ret = down_read_trylock(&mm->mmap_lock) != 0;
164 	__mmap_lock_trace_acquire_returned(mm, false, ret);
165 	return ret;
166 }
167 
mmap_read_unlock(struct mm_struct * mm)168 static inline void mmap_read_unlock(struct mm_struct *mm)
169 {
170 	__mmap_lock_trace_released(mm, false);
171 	up_read(&mm->mmap_lock);
172 }
173 
mmap_read_unlock_non_owner(struct mm_struct * mm)174 static inline void mmap_read_unlock_non_owner(struct mm_struct *mm)
175 {
176 	__mmap_lock_trace_released(mm, false);
177 	up_read_non_owner(&mm->mmap_lock);
178 }
179 
mmap_lock_is_contended(struct mm_struct * mm)180 static inline int mmap_lock_is_contended(struct mm_struct *mm)
181 {
182 	return rwsem_is_contended(&mm->mmap_lock);
183 }
184 
185 #endif /* _LINUX_MMAP_LOCK_H */
186