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(const struct mm_struct *mm)
  64 {
  65         rwsem_assert_held(&mm->mmap_lock);
  66 }
  67
  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 /*
  75  * Drop all currently-held per-VMA locks.
  76  * This is called from the mmap_lock implementation directly before releasing
  77  * a write-locked mmap_lock (or downgrading it to read-locked).
  78  * This should normally NOT be called manually from other places.
  79  * If you want to call this manually anyway, keep in mind that this will release
  80  * *all* VMA write locks, including ones from further up the stack.
  81  */
  82 static inline void vma_end_write_all(struct mm_struct *mm)
  83 {
  84         mmap_assert_write_locked(mm);
  85         /*
  86          * Nobody can concurrently modify mm->mm_lock_seq due to exclusive
  87          * mmap_lock being held.
  88          * We need RELEASE semantics here to ensure that preceding stores into
  89          * the VMA take effect before we unlock it with this store.
  90          * Pairs with ACQUIRE semantics in vma_start_read().
  91          */
  92         smp_store_release(&mm->mm_lock_seq, mm->mm_lock_seq + 1);
  93 }
  94 #else
  95 static inline void vma_end_write_all(struct mm_struct *mm) {}
  96 #endif
  97
  98 static inline void mmap_init_lock(struct mm_struct *mm)
  99 {
 100         init_rwsem(&mm->mmap_lock);
 101 }
 102
 103 static inline void mmap_write_lock(struct mm_struct *mm)
 104 {
 105         __mmap_lock_trace_start_locking(mm, true);
 106         down_write(&mm->mmap_lock);
 107         __mmap_lock_trace_acquire_returned(mm, true, true);
 108 }
 109
 110 static inline void mmap_write_lock_nested(struct mm_struct *mm, int subclass)
 111 {
 112         __mmap_lock_trace_start_locking(mm, true);
 113         down_write_nested(&mm->mmap_lock, subclass);
 114         __mmap_lock_trace_acquire_returned(mm, true, true);
 115 }
 116
 117 static inline int mmap_write_lock_killable(struct mm_struct *mm)
 118 {
 119         int ret;
 120
 121         __mmap_lock_trace_start_locking(mm, true);
 122         ret = down_write_killable(&mm->mmap_lock);
 123         __mmap_lock_trace_acquire_returned(mm, true, ret == 0);
 124         return ret;
 125 }
 126
 127 static inline void mmap_write_unlock(struct mm_struct *mm)
 128 {
 129         __mmap_lock_trace_released(mm, true);
 130         vma_end_write_all(mm);
 131         up_write(&mm->mmap_lock);
 132 }
 133
 134 static inline void mmap_write_downgrade(struct mm_struct *mm)
 135 {
 136         __mmap_lock_trace_acquire_returned(mm, false, true);
 137         vma_end_write_all(mm);
 138         downgrade_write(&mm->mmap_lock);
 139 }
 140
 141 static inline void mmap_read_lock(struct mm_struct *mm)
 142 {
 143         __mmap_lock_trace_start_locking(mm, false);
 144         down_read(&mm->mmap_lock);
 145         __mmap_lock_trace_acquire_returned(mm, false, true);
 146 }
 147
 148 static inline int mmap_read_lock_killable(struct mm_struct *mm)
 149 {
 150         int ret;
 151
 152         __mmap_lock_trace_start_locking(mm, false);
 153         ret = down_read_killable(&mm->mmap_lock);
 154         __mmap_lock_trace_acquire_returned(mm, false, ret == 0);
 155         return ret;
 156 }
 157
 158 static inline bool mmap_read_trylock(struct mm_struct *mm)
 159 {
 160         bool ret;
 161
 162         __mmap_lock_trace_start_locking(mm, false);
 163         ret = down_read_trylock(&mm->mmap_lock) != 0;
 164         __mmap_lock_trace_acquire_returned(mm, false, ret);
 165         return ret;
 166 }
 167
 168 static inline void mmap_read_unlock(struct mm_struct *mm)
 169 {
 170         __mmap_lock_trace_released(mm, false);
 171         up_read(&mm->mmap_lock);
 172 }
 173
 174 static inline void mmap_read_unlock_non_owner(struct mm_struct *mm)
 175 {
 176         __mmap_lock_trace_released(mm, false);
 177         up_read_non_owner(&mm->mmap_lock);
 178 }
 179
 180 static inline int mmap_lock_is_contended(struct mm_struct *mm)
 181 {
 182         return rwsem_is_contended(&mm->mmap_lock);
 183 }
 184
 185 #endif /* _LINUX_MMAP_LOCK_H */