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(const struct mm_struct *mm)
64 {
65 rwsem_assert_held(&mm->mmap_lock);
66 }
67
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 */
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
95 static inline void vma_end_write_all(struct mm_struct *mm) {}
96 #endif
97
98 static inline void mmap_init_lock(struct mm_struct *mm)
99 {
100 init_rwsem(&mm->mmap_lock);
101 }
102
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
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
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
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
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
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
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
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
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
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
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
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