Merge branch 'for-next' of git://git.samba.org/sfrench/cifs-2.6

[cascardo/linux.git] / mm / mmu_notifier.c

diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c
index 41cefdf..950813b 100644 (file)
--- a/mm/mmu_notifier.c
+++ b/mm/mmu_notifier.c
@@ -22,6 +22,25 @@
 /* global SRCU for all MMs */
 static struct srcu_struct srcu;
 
+/*
+ * This function allows mmu_notifier::release callback to delay a call to
+ * a function that will free appropriate resources. The function must be
+ * quick and must not block.
+ */
+void mmu_notifier_call_srcu(struct rcu_head *rcu,
+                           void (*func)(struct rcu_head *rcu))
+{
+       call_srcu(&srcu, rcu, func);
+}
+EXPORT_SYMBOL_GPL(mmu_notifier_call_srcu);
+
+void mmu_notifier_synchronize(void)
+{
+       /* Wait for any running method to finish. */
+       srcu_barrier(&srcu);
+}
+EXPORT_SYMBOL_GPL(mmu_notifier_synchronize);
+
 /*
  * This function can't run concurrently against mmu_notifier_register
  * because mm->mm_users > 0 during mmu_notifier_register and exit_mmap
@@ -53,7 +72,6 @@ void __mmu_notifier_release(struct mm_struct *mm)
                 */
                if (mn->ops->release)
                        mn->ops->release(mn, mm);
-       srcu_read_unlock(&srcu, id);
 
        spin_lock(&mm->mmu_notifier_mm->lock);
        while (unlikely(!hlist_empty(&mm->mmu_notifier_mm->list))) {
@@ -69,6 +87,7 @@ void __mmu_notifier_release(struct mm_struct *mm)
                hlist_del_init_rcu(&mn->hlist);
        }
        spin_unlock(&mm->mmu_notifier_mm->lock);
+       srcu_read_unlock(&srcu, id);
 
        /*
         * synchronize_srcu here prevents mmu_notifier_release from returning to
@@ -325,6 +344,25 @@ void mmu_notifier_unregister(struct mmu_notifier *mn, struct mm_struct *mm)
 }
 EXPORT_SYMBOL_GPL(mmu_notifier_unregister);
 
+/*
+ * Same as mmu_notifier_unregister but no callback and no srcu synchronization.
+ */
+void mmu_notifier_unregister_no_release(struct mmu_notifier *mn,
+                                       struct mm_struct *mm)
+{
+       spin_lock(&mm->mmu_notifier_mm->lock);
+       /*
+        * Can not use list_del_rcu() since __mmu_notifier_release
+        * can delete it before we hold the lock.
+        */
+       hlist_del_init_rcu(&mn->hlist);
+       spin_unlock(&mm->mmu_notifier_mm->lock);
+
+       BUG_ON(atomic_read(&mm->mm_count) <= 0);
+       mmdrop(mm);
+}
+EXPORT_SYMBOL_GPL(mmu_notifier_unregister_no_release);
+
 static int __init mmu_notifier_init(void)
 {
        return init_srcu_struct(&srcu);