include/linux/sched/mm.h

   1 #ifndef _LINUX_SCHED_MM_H
   2 #define _LINUX_SCHED_MM_H
   3
   4 #include <linux/sched.h>
   5 #include <linux/mm_types.h>
   6 #include <linux/gfp.h>
   7
   8 /*
   9  * Routines for handling mm_structs
  10  */
  11 extern struct mm_struct * mm_alloc(void);
  12
  13 /**
  14  * mmgrab() - Pin a &struct mm_struct.
  15  * @mm: The &struct mm_struct to pin.
  16  *
  17  * Make sure that @mm will not get freed even after the owning task
  18  * exits. This doesn't guarantee that the associated address space
  19  * will still exist later on and mmget_not_zero() has to be used before
  20  * accessing it.
  21  *
  22  * This is a preferred way to to pin @mm for a longer/unbounded amount
  23  * of time.
  24  *
  25  * Use mmdrop() to release the reference acquired by mmgrab().
  26  *
  27  * See also <Documentation/vm/active_mm.txt> for an in-depth explanation
  28  * of &mm_struct.mm_count vs &mm_struct.mm_users.
  29  */
  30 static inline void mmgrab(struct mm_struct *mm)
  31 {
  32         atomic_inc(&mm->mm_count);
  33 }
  34
  35 /* mmdrop drops the mm and the page tables */
  36 extern void __mmdrop(struct mm_struct *);
  37 static inline void mmdrop(struct mm_struct *mm)
  38 {
  39         if (unlikely(atomic_dec_and_test(&mm->mm_count)))
  40                 __mmdrop(mm);
  41 }
  42
  43 static inline void mmdrop_async_fn(struct work_struct *work)
  44 {
  45         struct mm_struct *mm = container_of(work, struct mm_struct, async_put_work);
  46         __mmdrop(mm);
  47 }
  48
  49 static inline void mmdrop_async(struct mm_struct *mm)
  50 {
  51         if (unlikely(atomic_dec_and_test(&mm->mm_count))) {
  52                 INIT_WORK(&mm->async_put_work, mmdrop_async_fn);
  53                 schedule_work(&mm->async_put_work);
  54         }
  55 }
  56
  57 /**
  58  * mmget() - Pin the address space associated with a &struct mm_struct.
  59  * @mm: The address space to pin.
  60  *
  61  * Make sure that the address space of the given &struct mm_struct doesn't
  62  * go away. This does not protect against parts of the address space being
  63  * modified or freed, however.
  64  *
  65  * Never use this function to pin this address space for an
  66  * unbounded/indefinite amount of time.
  67  *
  68  * Use mmput() to release the reference acquired by mmget().
  69  *
  70  * See also <Documentation/vm/active_mm.txt> for an in-depth explanation
  71  * of &mm_struct.mm_count vs &mm_struct.mm_users.
  72  */
  73 static inline void mmget(struct mm_struct *mm)
  74 {
  75         atomic_inc(&mm->mm_users);
  76 }
  77
  78 static inline bool mmget_not_zero(struct mm_struct *mm)
  79 {
  80         return atomic_inc_not_zero(&mm->mm_users);
  81 }
  82
  83 /* mmput gets rid of the mappings and all user-space */
  84 extern void mmput(struct mm_struct *);
  85 #ifdef CONFIG_MMU
  86 /* same as above but performs the slow path from the async context. Can
  87  * be called from the atomic context as well
  88  */
  89 extern void mmput_async(struct mm_struct *);
  90 #endif
  91
  92 /* Grab a reference to a task's mm, if it is not already going away */
  93 extern struct mm_struct *get_task_mm(struct task_struct *task);
  94 /*
  95  * Grab a reference to a task's mm, if it is not already going away
  96  * and ptrace_may_access with the mode parameter passed to it
  97  * succeeds.
  98  */
  99 extern struct mm_struct *mm_access(struct task_struct *task, unsigned int mode);
 100 /* Remove the current tasks stale references to the old mm_struct */
 101 extern void mm_release(struct task_struct *, struct mm_struct *);
 102
 103 #ifdef CONFIG_MEMCG
 104 extern void mm_update_next_owner(struct mm_struct *mm);
 105 #else
 106 static inline void mm_update_next_owner(struct mm_struct *mm)
 107 {
 108 }
 109 #endif /* CONFIG_MEMCG */
 110
 111 #ifdef CONFIG_MMU
 112 extern void arch_pick_mmap_layout(struct mm_struct *mm);
 113 extern unsigned long
 114 arch_get_unmapped_area(struct file *, unsigned long, unsigned long,
 115                        unsigned long, unsigned long);
 116 extern unsigned long
 117 arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
 118                           unsigned long len, unsigned long pgoff,
 119                           unsigned long flags);
 120 #else
 121 static inline void arch_pick_mmap_layout(struct mm_struct *mm) {}
 122 #endif
 123
 124 #endif /* _LINUX_SCHED_MM_H */