3 files changed, 38 insertions, 5 deletions

diff --git a/kernel/locking/rtmutex-debug.h b/kernel/locking/rtmutex-debug.h
index 14193d596d78..ab29b6a22669 100644
--- a/kernel/locking/rtmutex-debug.h
+++ b/kernel/locking/rtmutex-debug.h
@@ -31,3 +31,8 @@ static inline int debug_rt_mutex_detect_deadlock(struct rt_mutex_waiter *waiter,
 {
         return (waiter != NULL);
 }
+
+static inline void rt_mutex_print_deadlock(struct rt_mutex_waiter *w)
+{
+        debug_rt_mutex_print_deadlock(w);
+}
diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index a620d4d08ca6..eb7a46327798 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -314,7 +314,7 @@ static int rt_mutex_adjust_prio_chain(struct task_struct *task,
                 }
                 put_task_struct(task);
 
-                return deadlock_detect ? -EDEADLK : 0;
+                return -EDEADLK;
         }
  retry:
         /*
@@ -377,7 +377,7 @@ static int rt_mutex_adjust_prio_chain(struct task_struct *task,
         if (lock == orig_lock || rt_mutex_owner(lock) == top_task) {
                 debug_rt_mutex_deadlock(deadlock_detect, orig_waiter, lock);
                 raw_spin_unlock(&lock->wait_lock);
-                ret = deadlock_detect ? -EDEADLK : 0;
+                ret = -EDEADLK;
                 goto out_unlock_pi;
         }
 
@@ -548,7 +548,7 @@ static int task_blocks_on_rt_mutex(struct rt_mutex *lock,
          * which is wrong, as the other waiter is not in a deadlock
          * situation.
          */
-        if (detect_deadlock && owner == task)
+        if (owner == task)
                 return -EDEADLK;
 
         raw_spin_lock_irqsave(&task->pi_lock, flags);
@@ -763,6 +763,26 @@ __rt_mutex_slowlock(struct rt_mutex *lock, int state,
         return ret;
 }
 
+static void rt_mutex_handle_deadlock(int res, int detect_deadlock,
+                                     struct rt_mutex_waiter *w)
+{
+        /*
+         * If the result is not -EDEADLOCK or the caller requested
+         * deadlock detection, nothing to do here.
+         */
+        if (res != -EDEADLOCK || detect_deadlock)
+                return;
+
+        /*
+         * Yell lowdly and stop the task right here.
+         */
+        rt_mutex_print_deadlock(w);
+        while (1) {
+                set_current_state(TASK_INTERRUPTIBLE);
+                schedule();
+        }
+}
+
 /*
  * Slow path lock function:
  */
@@ -802,8 +822,10 @@ rt_mutex_slowlock(struct rt_mutex *lock, int state,
 
         set_current_state(TASK_RUNNING);
 
-        if (unlikely(ret))
+        if (unlikely(ret)) {
                 remove_waiter(lock, &waiter);
+                rt_mutex_handle_deadlock(ret, detect_deadlock, &waiter);
+        }
 
         /*
          * try_to_take_rt_mutex() sets the waiter bit
@@ -1112,7 +1134,8 @@ int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
                 return 1;
         }
 
-        ret = task_blocks_on_rt_mutex(lock, waiter, task, detect_deadlock);
+        /* We enforce deadlock detection for futexes */
+        ret = task_blocks_on_rt_mutex(lock, waiter, task, 1);
 
         if (ret && !rt_mutex_owner(lock)) {
                 /*
diff --git a/kernel/locking/rtmutex.h b/kernel/locking/rtmutex.h
index a1a1dd06421d..f6a1f3c133b1 100644
--- a/kernel/locking/rtmutex.h
+++ b/kernel/locking/rtmutex.h
@@ -24,3 +24,8 @@
 #define debug_rt_mutex_print_deadlock(w)                do { } while (0)
 #define debug_rt_mutex_detect_deadlock(w,d)             (d)
 #define debug_rt_mutex_reset_waiter(w)                  do { } while (0)
+
+static inline void rt_mutex_print_deadlock(struct rt_mutex_waiter *w)
+{
+        WARN(1, "rtmutex deadlock detected\n");
+}