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(struct mm_struct * mm)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
mmap_assert_write_locked(struct mm_struct * mm)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 /*
77 * Drop all currently-held per-VMA locks.
78 * This is called from the mmap_lock implementation directly before releasing
79 * a write-locked mmap_lock (or downgrading it to read-locked).
80 * This should normally NOT be called manually from other places.
81 * If you want to call this manually anyway, keep in mind that this will release
82 * *all* VMA write locks, including ones from further up the stack.
83 */
vma_end_write_all(struct mm_struct * mm)84 static inline void vma_end_write_all(struct mm_struct *mm)
85 {
86 mmap_assert_write_locked(mm);
87 /*
88 * Nobody can concurrently modify mm->mm_lock_seq due to exclusive
89 * mmap_lock being held.
90 * We need RELEASE semantics here to ensure that preceding stores into
91 * the VMA take effect before we unlock it with this store.
92 * Pairs with ACQUIRE semantics in vma_start_read().
93 */
94 smp_store_release(&mm->mm_lock_seq, mm->mm_lock_seq + 1);
95 }
96 #else
vma_end_write_all(struct mm_struct * mm)97 static inline void vma_end_write_all(struct mm_struct *mm) {}
98 #endif
99
mmap_init_lock(struct mm_struct * mm)100 static inline void mmap_init_lock(struct mm_struct *mm)
101 {
102 init_rwsem(&mm->mmap_lock);
103 }
104
mmap_write_lock(struct mm_struct * mm)105 static inline void mmap_write_lock(struct mm_struct *mm)
106 {
107 __mmap_lock_trace_start_locking(mm, true);
108 down_write(&mm->mmap_lock);
109 __mmap_lock_trace_acquire_returned(mm, true, true);
110 }
111
mmap_write_lock_nested(struct mm_struct * mm,int subclass)112 static inline void mmap_write_lock_nested(struct mm_struct *mm, int subclass)
113 {
114 __mmap_lock_trace_start_locking(mm, true);
115 down_write_nested(&mm->mmap_lock, subclass);
116 __mmap_lock_trace_acquire_returned(mm, true, true);
117 }
118
mmap_write_lock_killable(struct mm_struct * mm)119 static inline int mmap_write_lock_killable(struct mm_struct *mm)
120 {
121 int ret;
122
123 __mmap_lock_trace_start_locking(mm, true);
124 ret = down_write_killable(&mm->mmap_lock);
125 __mmap_lock_trace_acquire_returned(mm, true, ret == 0);
126 return ret;
127 }
128
mmap_write_unlock(struct mm_struct * mm)129 static inline void mmap_write_unlock(struct mm_struct *mm)
130 {
131 __mmap_lock_trace_released(mm, true);
132 vma_end_write_all(mm);
133 up_write(&mm->mmap_lock);
134 }
135
mmap_write_downgrade(struct mm_struct * mm)136 static inline void mmap_write_downgrade(struct mm_struct *mm)
137 {
138 __mmap_lock_trace_acquire_returned(mm, false, true);
139 vma_end_write_all(mm);
140 downgrade_write(&mm->mmap_lock);
141 }
142
mmap_read_lock(struct mm_struct * mm)143 static inline void mmap_read_lock(struct mm_struct *mm)
144 {
145 __mmap_lock_trace_start_locking(mm, false);
146 down_read(&mm->mmap_lock);
147 __mmap_lock_trace_acquire_returned(mm, false, true);
148 }
149
mmap_read_lock_killable(struct mm_struct * mm)150 static inline int mmap_read_lock_killable(struct mm_struct *mm)
151 {
152 int ret;
153
154 __mmap_lock_trace_start_locking(mm, false);
155 ret = down_read_killable(&mm->mmap_lock);
156 __mmap_lock_trace_acquire_returned(mm, false, ret == 0);
157 return ret;
158 }
159
mmap_read_trylock(struct mm_struct * mm)160 static inline bool mmap_read_trylock(struct mm_struct *mm)
161 {
162 bool ret;
163
164 __mmap_lock_trace_start_locking(mm, false);
165 ret = down_read_trylock(&mm->mmap_lock) != 0;
166 __mmap_lock_trace_acquire_returned(mm, false, ret);
167 return ret;
168 }
169
mmap_read_unlock(struct mm_struct * mm)170 static inline void mmap_read_unlock(struct mm_struct *mm)
171 {
172 __mmap_lock_trace_released(mm, false);
173 up_read(&mm->mmap_lock);
174 }
175
mmap_read_unlock_non_owner(struct mm_struct * mm)176 static inline void mmap_read_unlock_non_owner(struct mm_struct *mm)
177 {
178 __mmap_lock_trace_released(mm, false);
179 up_read_non_owner(&mm->mmap_lock);
180 }
181
mmap_lock_is_contended(struct mm_struct * mm)182 static inline int mmap_lock_is_contended(struct mm_struct *mm)
183 {
184 return rwsem_is_contended(&mm->mmap_lock);
185 }
186
187 #endif /* _LINUX_MMAP_LOCK_H */
188