mm: add new mmget() helper

[sfrench/cifs-2.6.git] / include / linux / sched.h

diff --git a/include/linux/sched.h b/include/linux/sched.h
index c8e519d0b4a35153c823c6ee172fd7ca26f43402..4a28deb5f210a103d486fa12c509405f92f4ca60 100644 (file)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -846,10 +846,6 @@ struct user_struct {
        atomic_t __count;       /* reference count */
        atomic_t processes;     /* How many processes does this user have? */
        atomic_t sigpending;    /* How many pending signals does this user have? */
-#ifdef CONFIG_INOTIFY_USER
-       atomic_t inotify_watches; /* How many inotify watches does this user have? */
-       atomic_t inotify_devs;  /* How many inotify devs does this user have opened? */
-#endif
 #ifdef CONFIG_FANOTIFY
        atomic_t fanotify_listeners;
 #endif
@@ -2908,6 +2904,28 @@ static inline unsigned long sigsp(unsigned long sp, struct ksignal *ksig)
  */
 extern struct mm_struct * mm_alloc(void);
 
+/**
+ * mmgrab() - Pin a &struct mm_struct.
+ * @mm: The &struct mm_struct to pin.
+ *
+ * Make sure that @mm will not get freed even after the owning task
+ * exits. This doesn't guarantee that the associated address space
+ * will still exist later on and mmget_not_zero() has to be used before
+ * accessing it.
+ *
+ * This is a preferred way to to pin @mm for a longer/unbounded amount
+ * of time.
+ *
+ * Use mmdrop() to release the reference acquired by mmgrab().
+ *
+ * See also <Documentation/vm/active_mm.txt> for an in-depth explanation
+ * of &mm_struct.mm_count vs &mm_struct.mm_users.
+ */
+static inline void mmgrab(struct mm_struct *mm)
+{
+       atomic_inc(&mm->mm_count);
+}
+
 /* mmdrop drops the mm and the page tables */
 extern void __mmdrop(struct mm_struct *);
 static inline void mmdrop(struct mm_struct *mm)
@@ -2930,6 +2948,27 @@ static inline void mmdrop_async(struct mm_struct *mm)
        }
 }
 
+/**
+ * mmget() - Pin the address space associated with a &struct mm_struct.
+ * @mm: The address space to pin.
+ *
+ * Make sure that the address space of the given &struct mm_struct doesn't
+ * go away. This does not protect against parts of the address space being
+ * modified or freed, however.
+ *
+ * Never use this function to pin this address space for an
+ * unbounded/indefinite amount of time.
+ *
+ * Use mmput() to release the reference acquired by mmget().
+ *
+ * See also <Documentation/vm/active_mm.txt> for an in-depth explanation
+ * of &mm_struct.mm_count vs &mm_struct.mm_users.
+ */
+static inline void mmget(struct mm_struct *mm)
+{
+       atomic_inc(&mm->mm_users);
+}
+
 static inline bool mmget_not_zero(struct mm_struct *mm)
 {
        return atomic_inc_not_zero(&mm->mm_users);
@@ -3051,6 +3090,9 @@ extern bool current_is_single_threaded(void);
 #define for_each_process_thread(p, t)  \
        for_each_process(p) for_each_thread(p, t)
 
+typedef int (*proc_visitor)(struct task_struct *p, void *data);
+void walk_process_tree(struct task_struct *top, proc_visitor, void *);
+
 static inline int get_nr_threads(struct task_struct *tsk)
 {
        return tsk->signal->nr_threads;