sched: Add a preempt count base offset to __might_sleep()

Add a preempt count base offset to compare against the current
preempt level count. It prepares to pull up the might_sleep
check from cond_resched() to cond_resched_lock() and
cond_resched_bh().

For these two helpers, we need to respectively ensure that once
we'll unlock the given spinlock / reenable local softirqs, we
will reach a sleepable state.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
[ Move and rename preempt_count_equals() ]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1247725694-6082-4-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index b804f69..2b5b1e0 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -125,7 +125,7 @@
 #endif
 
 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
-  void __might_sleep(char *file, int line);
+  void __might_sleep(char *file, int line, int preempt_offset);
 /**
  * might_sleep - annotation for functions that can sleep
  *
@@ -137,9 +137,9 @@
  * supposed to.
  */
 # define might_sleep() \
-	do { __might_sleep(__FILE__, __LINE__); might_resched(); } while (0)
+	do { __might_sleep(__FILE__, __LINE__, 0); might_resched(); } while (0)
 #else
-  static inline void __might_sleep(char *file, int line) { }
+  static inline void __might_sleep(char *file, int line, int preempt_offset) { }
 # define might_sleep() do { might_resched(); } while (0)
 #endif