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(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
69static 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 */
84static 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
97static inline void vma_end_write_all(struct mm_struct *mm) {}
98#endif
99
100static inline void mmap_init_lock(struct mm_struct *mm)
101{
102	init_rwsem(&mm->mmap_lock);
103}
104
105static 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
112static 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
119static 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
129static 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
136static 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
143static 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
150static 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
160static 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
170static 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
176static 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
182static 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