Linux kernel mirror (for testing)
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linux
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
14DECLARE_TRACEPOINT(mmap_lock_start_locking);
15DECLARE_TRACEPOINT(mmap_lock_acquire_returned);
16DECLARE_TRACEPOINT(mmap_lock_released);
17
18#ifdef CONFIG_TRACING
19
20void __mmap_lock_do_trace_start_locking(struct mm_struct *mm, bool write);
21void __mmap_lock_do_trace_acquire_returned(struct mm_struct *mm, bool write,
22 bool success);
23void __mmap_lock_do_trace_released(struct mm_struct *mm, bool write);
24
25static 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
32static 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
39static 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
47static inline void __mmap_lock_trace_start_locking(struct mm_struct *mm,
48 bool write)
49{
50}
51
52static inline void __mmap_lock_trace_acquire_returned(struct mm_struct *mm,
53 bool write, bool success)
54{
55}
56
57static inline void __mmap_lock_trace_released(struct mm_struct *mm, bool write)
58{
59}
60
61#endif /* CONFIG_TRACING */
62
63static inline void mmap_assert_locked(const struct mm_struct *mm)
64{
65 rwsem_assert_held(&mm->mmap_lock);
66}
67
68static 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
75static inline void mm_lock_seqcount_init(struct mm_struct *mm)
76{
77 seqcount_init(&mm->mm_lock_seq);
78}
79
80static inline void mm_lock_seqcount_begin(struct mm_struct *mm)
81{
82 do_raw_write_seqcount_begin(&mm->mm_lock_seq);
83}
84
85static 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
91static 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
102static 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
109static inline void mm_lock_seqcount_init(struct mm_struct *mm) {}
110static inline void mm_lock_seqcount_begin(struct mm_struct *mm) {}
111static inline void mm_lock_seqcount_end(struct mm_struct *mm) {}
112
113static inline bool mmap_lock_speculate_try_begin(struct mm_struct *mm, unsigned int *seq)
114{
115 return false;
116}
117
118static 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
125static inline void mmap_write_lock(struct mm_struct *mm)
126{
127 __mmap_lock_trace_start_locking(mm, true);
128 down_write(&mm->mmap_lock);
129 mm_lock_seqcount_begin(mm);
130 __mmap_lock_trace_acquire_returned(mm, true, true);
131}
132
133static inline void mmap_write_lock_nested(struct mm_struct *mm, int subclass)
134{
135 __mmap_lock_trace_start_locking(mm, true);
136 down_write_nested(&mm->mmap_lock, subclass);
137 mm_lock_seqcount_begin(mm);
138 __mmap_lock_trace_acquire_returned(mm, true, true);
139}
140
141static inline int mmap_write_lock_killable(struct mm_struct *mm)
142{
143 int ret;
144
145 __mmap_lock_trace_start_locking(mm, true);
146 ret = down_write_killable(&mm->mmap_lock);
147 if (!ret)
148 mm_lock_seqcount_begin(mm);
149 __mmap_lock_trace_acquire_returned(mm, true, ret == 0);
150 return ret;
151}
152
153/*
154 * Drop all currently-held per-VMA locks.
155 * This is called from the mmap_lock implementation directly before releasing
156 * a write-locked mmap_lock (or downgrading it to read-locked).
157 * This should normally NOT be called manually from other places.
158 * If you want to call this manually anyway, keep in mind that this will release
159 * *all* VMA write locks, including ones from further up the stack.
160 */
161static inline void vma_end_write_all(struct mm_struct *mm)
162{
163 mmap_assert_write_locked(mm);
164 mm_lock_seqcount_end(mm);
165}
166
167static inline void mmap_write_unlock(struct mm_struct *mm)
168{
169 __mmap_lock_trace_released(mm, true);
170 vma_end_write_all(mm);
171 up_write(&mm->mmap_lock);
172}
173
174static inline void mmap_write_downgrade(struct mm_struct *mm)
175{
176 __mmap_lock_trace_acquire_returned(mm, false, true);
177 vma_end_write_all(mm);
178 downgrade_write(&mm->mmap_lock);
179}
180
181static inline void mmap_read_lock(struct mm_struct *mm)
182{
183 __mmap_lock_trace_start_locking(mm, false);
184 down_read(&mm->mmap_lock);
185 __mmap_lock_trace_acquire_returned(mm, false, true);
186}
187
188static inline int mmap_read_lock_killable(struct mm_struct *mm)
189{
190 int ret;
191
192 __mmap_lock_trace_start_locking(mm, false);
193 ret = down_read_killable(&mm->mmap_lock);
194 __mmap_lock_trace_acquire_returned(mm, false, ret == 0);
195 return ret;
196}
197
198static inline bool mmap_read_trylock(struct mm_struct *mm)
199{
200 bool ret;
201
202 __mmap_lock_trace_start_locking(mm, false);
203 ret = down_read_trylock(&mm->mmap_lock) != 0;
204 __mmap_lock_trace_acquire_returned(mm, false, ret);
205 return ret;
206}
207
208static inline void mmap_read_unlock(struct mm_struct *mm)
209{
210 __mmap_lock_trace_released(mm, false);
211 up_read(&mm->mmap_lock);
212}
213
214static inline void mmap_read_unlock_non_owner(struct mm_struct *mm)
215{
216 __mmap_lock_trace_released(mm, false);
217 up_read_non_owner(&mm->mmap_lock);
218}
219
220static inline int mmap_lock_is_contended(struct mm_struct *mm)
221{
222 return rwsem_is_contended(&mm->mmap_lock);
223}
224
225#endif /* _LINUX_MMAP_LOCK_H */