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 */ 188