sched/debug: Fix task state recording/printout

The recent conversion of the task state recording to use task_state_index()
broke the sched_switch tracepoint task state output.

task_state_index() returns surprisingly an index (0-7) which is then
printed with __print_flags() applying bitmasks. Not really working and
resulting in weird states like 'prev_state=t' instead of 'prev_state=I'.

Use TASK_REPORT_MAX instead of TASK_STATE_MAX to report preemption. Build a
bitmask from the return value of task_state_index() and store it in
entry->prev_state, which makes __print_flags() work as expected.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: stable@vger.kernel.org
Fixes: efb40f588b43 ("sched/tracing: Fix trace_sched_switch task-state printing")
Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1711221304180.1751@nanos
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
index 306b31de519417790a50ab9dcb510faafd44cb30..bc01e06bc7167fb2557ccb94e21c58e55f9c8fdb 100644 (file)
--- a/include/trace/events/sched.h
+++ b/include/trace/events/sched.h
@@ -116,9 +116,9 @@ static inline long __trace_sched_switch_state(bool preempt, struct task_struct *
         * RUNNING (we will not have dequeued if state != RUNNING).
         */
        if (preempt)
-               return TASK_STATE_MAX;
+               return TASK_REPORT_MAX;
 
-       return task_state_index(p);
+       return 1 << task_state_index(p);
 }
 #endif /* CREATE_TRACE_POINTS */
 
@@ -164,7 +164,7 @@ TRACE_EVENT(sched_switch,
                                { 0x40, "P" }, { 0x80, "I" }) :
                  "R",
 
-               __entry->prev_state & TASK_STATE_MAX ? "+" : "",
+               __entry->prev_state & TASK_REPORT_MAX ? "+" : "",
                __entry->next_comm, __entry->next_pid, __entry->next_prio)
 );