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 /*
  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  */
  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
  97 static inline void vma_end_write_all(struct mm_struct *mm) {}
  98 #endif
  99
 100 static inline void mmap_init_lock(struct mm_struct *mm)
 101 {
 102         init_rwsem(&mm->mmap_lock);
 103 }
 104
 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
 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
 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
 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
 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
 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
 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
 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
 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
 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
 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 */