include/linux/mmap_lock.h

   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(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
  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 static inline void vma_end_write_all(struct mm_struct *mm)
  77 {
  78         mmap_assert_write_locked(mm);
  79         /*
  80          * Nobody can concurrently modify mm->mm_lock_seq due to exclusive
  81          * mmap_lock being held.
  82          * We need RELEASE semantics here to ensure that preceding stores into
  83          * the VMA take effect before we unlock it with this store.
  84          * Pairs with ACQUIRE semantics in vma_start_read().
  85          */
  86         smp_store_release(&mm->mm_lock_seq, mm->mm_lock_seq + 1);
  87 }
  88 #else
  89 static inline void vma_end_write_all(struct mm_struct *mm) {}
  90 #endif
  91
  92 static inline void mmap_init_lock(struct mm_struct *mm)
  93 {
  94         init_rwsem(&mm->mmap_lock);
  95 }
  96
  97 static inline void mmap_write_lock(struct mm_struct *mm)
  98 {
  99         __mmap_lock_trace_start_locking(mm, true);
 100         down_write(&mm->mmap_lock);
 101         __mmap_lock_trace_acquire_returned(mm, true, true);
 102 }
 103
 104 static inline void mmap_write_lock_nested(struct mm_struct *mm, int subclass)
 105 {
 106         __mmap_lock_trace_start_locking(mm, true);
 107         down_write_nested(&mm->mmap_lock, subclass);
 108         __mmap_lock_trace_acquire_returned(mm, true, true);
 109 }
 110
 111 static inline int mmap_write_lock_killable(struct mm_struct *mm)
 112 {
 113         int ret;
 114
 115         __mmap_lock_trace_start_locking(mm, true);
 116         ret = down_write_killable(&mm->mmap_lock);
 117         __mmap_lock_trace_acquire_returned(mm, true, ret == 0);
 118         return ret;
 119 }
 120
 121 static inline bool mmap_write_trylock(struct mm_struct *mm)
 122 {
 123         bool ret;
 124
 125         __mmap_lock_trace_start_locking(mm, true);
 126         ret = down_write_trylock(&mm->mmap_lock) != 0;
 127         __mmap_lock_trace_acquire_returned(mm, true, ret);
 128         return ret;
 129 }
 130
 131 static inline void mmap_write_unlock(struct mm_struct *mm)
 132 {
 133         __mmap_lock_trace_released(mm, true);
 134         vma_end_write_all(mm);
 135         up_write(&mm->mmap_lock);
 136 }
 137
 138 static inline void mmap_write_downgrade(struct mm_struct *mm)
 139 {
 140         __mmap_lock_trace_acquire_returned(mm, false, true);
 141         vma_end_write_all(mm);
 142         downgrade_write(&mm->mmap_lock);
 143 }
 144
 145 static inline void mmap_read_lock(struct mm_struct *mm)
 146 {
 147         __mmap_lock_trace_start_locking(mm, false);
 148         down_read(&mm->mmap_lock);
 149         __mmap_lock_trace_acquire_returned(mm, false, true);
 150 }
 151
 152 static inline int mmap_read_lock_killable(struct mm_struct *mm)
 153 {
 154         int ret;
 155
 156         __mmap_lock_trace_start_locking(mm, false);
 157         ret = down_read_killable(&mm->mmap_lock);
 158         __mmap_lock_trace_acquire_returned(mm, false, ret == 0);
 159         return ret;
 160 }
 161
 162 static inline bool mmap_read_trylock(struct mm_struct *mm)
 163 {
 164         bool ret;
 165
 166         __mmap_lock_trace_start_locking(mm, false);
 167         ret = down_read_trylock(&mm->mmap_lock) != 0;
 168         __mmap_lock_trace_acquire_returned(mm, false, ret);
 169         return ret;
 170 }
 171
 172 static inline void mmap_read_unlock(struct mm_struct *mm)
 173 {
 174         __mmap_lock_trace_released(mm, false);
 175         up_read(&mm->mmap_lock);
 176 }
 177
 178 static inline void mmap_read_unlock_non_owner(struct mm_struct *mm)
 179 {
 180         __mmap_lock_trace_released(mm, false);
 181         up_read_non_owner(&mm->mmap_lock);
 182 }
 183
 184 static inline int mmap_lock_is_contended(struct mm_struct *mm)
 185 {
 186         return rwsem_is_contended(&mm->mmap_lock);
 187 }
 188
 189 #endif /* _LINUX_MMAP_LOCK_H */