Commit-ID:  8f9fbf092cd0ae31722b42c9abb427a87d55c18a
Gitweb:     http://git.kernel.org/tip/8f9fbf092cd0ae31722b42c9abb427a87d55c18a
Author:     Oleg Nesterov <[email protected]>
AuthorDate: Tue, 7 Oct 2014 21:51:08 +0200
Committer:  Ingo Molnar <[email protected]>
CommitDate: Tue, 28 Oct 2014 10:47:53 +0100

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]>
---
 include/trace/events/sched.h | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
index 0a68d5a..30fedaf 100644
--- 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:
--
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