sched: Fix the PREEMPT_ACTIVE check in __trace_sched_switch_state()

task_preempt_count() has nothing to do with the actual preempt counter,
thread_info->saved_preempt_count is only valid right after switch_to().

__trace_sched_switch_state() can use preempt_count(), prev is still the
current task when trace_sched_switch() is called.

Signed-off-by: Oleg Nesterov <[email protected]>
[ Added BUG_ON(). ]
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Steven Rostedt <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
index 0a68d5ae584e9dfada372fdae49c5d0934176402..30fedaf3e56a253175619fbef7a9f9a1f6dc15a3 100644 (file)
--- a/include/trace/events/sched.h
+++ b/include/trace/events/sched.h
@@ -97,16 +97,19 @@ static inline long __trace_sched_switch_state(struct task_struct *p)
        long state = p->state;
 
 #ifdef CONFIG_PREEMPT
+#ifdef CONFIG_SCHED_DEBUG
+       BUG_ON(p != current);
+#endif /* CONFIG_SCHED_DEBUG */
        /*
         * For all intents and purposes a preempted task is a running task.
         */
-       if (task_preempt_count(p) & PREEMPT_ACTIVE)
+       if (preempt_count() & PREEMPT_ACTIVE)
                state = TASK_RUNNING | TASK_STATE_MAX;
-#endif
+#endif /* CONFIG_PREEMPT */
 
        return state;
 }
-#endif
+#endif /* CREATE_TRACE_POINTS */
 
 /*
  * Tracepoint for task switches, performed by the scheduler: