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
mm_lock_seqcount_init(struct mm_struct * mm)75 static inline void mm_lock_seqcount_init(struct mm_struct *mm)
76 {
77 seqcount_init(&mm->mm_lock_seq);
78 }
79
mm_lock_seqcount_begin(struct mm_struct * mm)80 static inline void mm_lock_seqcount_begin(struct mm_struct *mm)
81 {
82 do_raw_write_seqcount_begin(&mm->mm_lock_seq);
83 }
84
mm_lock_seqcount_end(struct mm_struct * mm)85 static inline void mm_lock_seqcount_end(struct mm_struct *mm)
86 {
87 ASSERT_EXCLUSIVE_WRITER(mm->mm_lock_seq);
88 do_raw_write_seqcount_end(&mm->mm_lock_seq);
89 }
90
mmap_lock_speculate_try_begin(struct mm_struct * mm,unsigned int * seq)91 static inline bool mmap_lock_speculate_try_begin(struct mm_struct *mm, unsigned int *seq)
92 {
93 /*
94 * Since mmap_lock is a sleeping lock, and waiting for it to become
95 * unlocked is more or less equivalent with taking it ourselves, don't
96 * bother with the speculative path if mmap_lock is already write-locked
97 * and take the slow path, which takes the lock.
98 */
99 return raw_seqcount_try_begin(&mm->mm_lock_seq, *seq);
100 }
101
mmap_lock_speculate_retry(struct mm_struct * mm,unsigned int seq)102 static inline bool mmap_lock_speculate_retry(struct mm_struct *mm, unsigned int seq)
103 {
104 return read_seqcount_retry(&mm->mm_lock_seq, seq);
105 }
106
107 #else /* CONFIG_PER_VMA_LOCK */
108
mm_lock_seqcount_init(struct mm_struct * mm)109 static inline void mm_lock_seqcount_init(struct mm_struct *mm) {}
mm_lock_seqcount_begin(struct mm_struct * mm)110 static inline void mm_lock_seqcount_begin(struct mm_struct *mm) {}
mm_lock_seqcount_end(struct mm_struct * mm)111 static inline void mm_lock_seqcount_end(struct mm_struct *mm) {}
112
mmap_lock_speculate_try_begin(struct mm_struct * mm,unsigned int * seq)113 static inline bool mmap_lock_speculate_try_begin(struct mm_struct *mm, unsigned int *seq)
114 {
115 return false;
116 }
117
mmap_lock_speculate_retry(struct mm_struct * mm,unsigned int seq)118 static inline bool mmap_lock_speculate_retry(struct mm_struct *mm, unsigned int seq)
119 {
120 return true;
121 }
122
123 #endif /* CONFIG_PER_VMA_LOCK */
124
mmap_init_lock(struct mm_struct * mm)125 static inline void mmap_init_lock(struct mm_struct *mm)
126 {
127 init_rwsem(&mm->mmap_lock);
128 mm_lock_seqcount_init(mm);
129 }
130
mmap_write_lock(struct mm_struct * mm)131 static inline void mmap_write_lock(struct mm_struct *mm)
132 {
133 __mmap_lock_trace_start_locking(mm, true);
134 down_write(&mm->mmap_lock);
135 mm_lock_seqcount_begin(mm);
136 __mmap_lock_trace_acquire_returned(mm, true, true);
137 }
138
mmap_write_lock_nested(struct mm_struct * mm,int subclass)139 static inline void mmap_write_lock_nested(struct mm_struct *mm, int subclass)
140 {
141 __mmap_lock_trace_start_locking(mm, true);
142 down_write_nested(&mm->mmap_lock, subclass);
143 mm_lock_seqcount_begin(mm);
144 __mmap_lock_trace_acquire_returned(mm, true, true);
145 }
146
mmap_write_lock_killable(struct mm_struct * mm)147 static inline int mmap_write_lock_killable(struct mm_struct *mm)
148 {
149 int ret;
150
151 __mmap_lock_trace_start_locking(mm, true);
152 ret = down_write_killable(&mm->mmap_lock);
153 if (!ret)
154 mm_lock_seqcount_begin(mm);
155 __mmap_lock_trace_acquire_returned(mm, true, ret == 0);
156 return ret;
157 }
158
159 /*
160 * Drop all currently-held per-VMA locks.
161 * This is called from the mmap_lock implementation directly before releasing
162 * a write-locked mmap_lock (or downgrading it to read-locked).
163 * This should normally NOT be called manually from other places.
164 * If you want to call this manually anyway, keep in mind that this will release
165 * *all* VMA write locks, including ones from further up the stack.
166 */
vma_end_write_all(struct mm_struct * mm)167 static inline void vma_end_write_all(struct mm_struct *mm)
168 {
169 mmap_assert_write_locked(mm);
170 mm_lock_seqcount_end(mm);
171 }
172
mmap_write_unlock(struct mm_struct * mm)173 static inline void mmap_write_unlock(struct mm_struct *mm)
174 {
175 __mmap_lock_trace_released(mm, true);
176 vma_end_write_all(mm);
177 up_write(&mm->mmap_lock);
178 }
179
mmap_write_downgrade(struct mm_struct * mm)180 static inline void mmap_write_downgrade(struct mm_struct *mm)
181 {
182 __mmap_lock_trace_acquire_returned(mm, false, true);
183 vma_end_write_all(mm);
184 downgrade_write(&mm->mmap_lock);
185 }
186
mmap_read_lock(struct mm_struct * mm)187 static inline void mmap_read_lock(struct mm_struct *mm)
188 {
189 __mmap_lock_trace_start_locking(mm, false);
190 down_read(&mm->mmap_lock);
191 __mmap_lock_trace_acquire_returned(mm, false, true);
192 }
193
mmap_read_lock_killable(struct mm_struct * mm)194 static inline int mmap_read_lock_killable(struct mm_struct *mm)
195 {
196 int ret;
197
198 __mmap_lock_trace_start_locking(mm, false);
199 ret = down_read_killable(&mm->mmap_lock);
200 __mmap_lock_trace_acquire_returned(mm, false, ret == 0);
201 return ret;
202 }
203
mmap_read_trylock(struct mm_struct * mm)204 static inline bool mmap_read_trylock(struct mm_struct *mm)
205 {
206 bool ret;
207
208 __mmap_lock_trace_start_locking(mm, false);
209 ret = down_read_trylock(&mm->mmap_lock) != 0;
210 __mmap_lock_trace_acquire_returned(mm, false, ret);
211 return ret;
212 }
213
mmap_read_unlock(struct mm_struct * mm)214 static inline void mmap_read_unlock(struct mm_struct *mm)
215 {
216 __mmap_lock_trace_released(mm, false);
217 up_read(&mm->mmap_lock);
218 }
219
mmap_read_unlock_non_owner(struct mm_struct * mm)220 static inline void mmap_read_unlock_non_owner(struct mm_struct *mm)
221 {
222 __mmap_lock_trace_released(mm, false);
223 up_read_non_owner(&mm->mmap_lock);
224 }
225
mmap_lock_is_contended(struct mm_struct * mm)226 static inline int mmap_lock_is_contended(struct mm_struct *mm)
227 {
228 return rwsem_is_contended(&mm->mmap_lock);
229 }
230
231 #endif /* _LINUX_MMAP_LOCK_H */
232