3 files changed, 24 insertions, 15 deletions

diff --git a/Documentation/cgroups/resource_counter.txt b/Documentation/cgroups/resource_counter.txt
index 0c4a344e78fa..c4d99ed0b418 100644
--- a/Documentation/cgroups/resource_counter.txt
+++ b/Documentation/cgroups/resource_counter.txt
@@ -83,16 +83,17 @@ to work with it.
         res_counter->lock internally (it must be called with res_counter->lock
         held). The force parameter indicates whether we can bypass the limit.
 
- e. void res_counter_uncharge[_locked]
+ e. u64 res_counter_uncharge[_locked]
                         (struct res_counter *rc, unsigned long val)
 
         When a resource is released (freed) it should be de-accounted
         from the resource counter it was accounted to.  This is called
-        "uncharging".
+        "uncharging". The return value of this function indicate the amount
+        of charges still present in the counter.
 
         The _locked routines imply that the res_counter->lock is taken.
 
- f. void res_counter_uncharge_until
+ f. u64 res_counter_uncharge_until
                 (struct res_counter *rc, struct res_counter *top,
                  unsinged long val)
 
diff --git a/include/linux/res_counter.h b/include/linux/res_counter.h
index 6f54e40fa218..5ae8456d9670 100644
--- a/include/linux/res_counter.h
+++ b/include/linux/res_counter.h
@@ -125,14 +125,16 @@ int res_counter_charge_nofail(struct res_counter *counter,
  *
  * these calls check for usage underflow and show a warning on the console
  * _locked call expects the counter->lock to be taken
+ *
+ * returns the total charges still present in @counter.
  */
 
-void res_counter_uncharge_locked(struct res_counter *counter, unsigned long val);
-void res_counter_uncharge(struct res_counter *counter, unsigned long val);
+u64 res_counter_uncharge_locked(struct res_counter *counter, unsigned long val);
+u64 res_counter_uncharge(struct res_counter *counter, unsigned long val);
 
-void res_counter_uncharge_until(struct res_counter *counter,
-                                struct res_counter *top,
-                                unsigned long val);
+u64 res_counter_uncharge_until(struct res_counter *counter,
+                               struct res_counter *top,
+                               unsigned long val);
 /**
  * res_counter_margin - calculate chargeable space of a counter
  * @cnt: the counter
diff --git a/kernel/res_counter.c b/kernel/res_counter.c
index 3920d593e63c..ff55247e7049 100644
--- a/kernel/res_counter.c
+++ b/kernel/res_counter.c
@@ -86,33 +86,39 @@ int res_counter_charge_nofail(struct res_counter *counter, unsigned long val,
         return __res_counter_charge(counter, val, limit_fail_at, true);
 }
 
-void res_counter_uncharge_locked(struct res_counter *counter, unsigned long val)
+u64 res_counter_uncharge_locked(struct res_counter *counter, unsigned long val)
 {
         if (WARN_ON(counter->usage < val))
                 val = counter->usage;
 
         counter->usage -= val;
+        return counter->usage;
 }
 
-void res_counter_uncharge_until(struct res_counter *counter,
-                                struct res_counter *top,
-                                unsigned long val)
+u64 res_counter_uncharge_until(struct res_counter *counter,
+                               struct res_counter *top,
+                               unsigned long val)
 {
         unsigned long flags;
         struct res_counter *c;
+        u64 ret = 0;
 
         local_irq_save(flags);
         for (c = counter; c != top; c = c->parent) {
+                u64 r;
                 spin_lock(&c->lock);
-                res_counter_uncharge_locked(c, val);
+                r = res_counter_uncharge_locked(c, val);
+                if (c == counter)
+                        ret = r;
                 spin_unlock(&c->lock);
         }
         local_irq_restore(flags);
+        return ret;
 }
 
-void res_counter_uncharge(struct res_counter *counter, unsigned long val)
+u64 res_counter_uncharge(struct res_counter *counter, unsigned long val)
 {
-        res_counter_uncharge_until(counter, NULL, val);
+        return res_counter_uncharge_until(counter, NULL, val);
 }
 
 static inline unsigned long long *