linux-kernel - [tip:sched/urgent] sched/debug: Fix task state recording/printout

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Message-ID: <tip-3f5fe9fef5b2da06b6319fab8123056da5217c3f@git.kernel.org>
Date:   Fri, 24 Nov 2017 00:49:04 -0800
From:   tip-bot for Thomas Gleixner <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     mingo@...nel.org, linux-kernel@...r.kernel.org,
        torvalds@...ux-foundation.org, paulmck@...ux.vnet.ibm.com,
        peterz@...radead.org, rostedt@...dmis.org, hpa@...or.com,
        tglx@...utronix.de
Subject: [tip:sched/urgent] sched/debug: Fix task state recording/printout

Commit-ID:  3f5fe9fef5b2da06b6319fab8123056da5217c3f
Gitweb:     https://git.kernel.org/tip/3f5fe9fef5b2da06b6319fab8123056da5217c3f
Author:     Thomas Gleixner <tglx@...utronix.de>
AuthorDate: Wed, 22 Nov 2017 13:05:48 +0100
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Fri, 24 Nov 2017 08:39:12 +0100

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@...utronix.de>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: stable@...r.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@...nel.org>
---
 include/trace/events/sched.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
index 306b31d..bc01e06 100644
--- 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)
 );