1 files changed, 28 insertions, 0 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h
index e6c24f2bfadd..b132cc3952ea 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -956,6 +956,34 @@ static inline void cond_resched(void)
 		__cond_resched();
 }
 
+#ifdef CONFIG_PREEMPT
+
+/*
+ * cond_resched_lock() - if a reschedule is pending, drop the given lock,
+ * call schedule, and on return reacquire the lock.
+ *
+ * Note: this does not assume the given lock is the _only_ lock held.
+ * The kernel preemption counter gives us "free" checking that we are
+ * atomic -- let's use it.
+ */
+static inline void cond_resched_lock(spinlock_t * lock)
+{
+	if (need_resched() && preempt_count() == 1) {
+		_raw_spin_unlock(lock);
+		preempt_enable_no_resched();
+		__cond_resched();
+		spin_lock(lock);
+	}
+}
+
+#else
+
+static inline void cond_resched_lock(spinlock_t * lock)
+{
+}
+
+#endif
+
 /* Reevaluate whether the task has signals pending delivery.
    This is required every time the blocked sigset_t changes.
    Athread cathreaders should have t->sigmask_lock.  */