From: Pavankumar Kondeti <pkondeti@codeaurora.org>
To: Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@kernel.org>,
linux-kernel@vger.kernel.org
Cc: Pavankumar Kondeti <pkondeti@codeaurora.org>
Subject: [PATCH] sched, trace: Fix prev_state output in sched_switch tracepoint
Date: Tue, 30 Oct 2018 12:24:33 +0530 [thread overview]
Message-ID: <1540882473-1103-1-git-send-email-pkondeti@codeaurora.org> (raw)
commit 3f5fe9fef5b2 ("sched/debug: Fix task state recording/printout")
tried to fix the problem introduced by a previous commit efb40f588b43
("sched/tracing: Fix trace_sched_switch task-state printing"). However
the prev_state output in sched_switch is still broken.
task_state_index() uses fls() which considers the LSB as 1. Left
shifting 1 by this value gives an incorrect mapping to the task state.
Fix this by decrementing the value returned by __get_task_state()
before shifting.
Fixes: 3f5fe9fef5b2 ("sched/debug: Fix task state recording/printout")
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>
---
include/trace/events/sched.h | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
index f07b270..9a4bdfa 100644
--- a/include/trace/events/sched.h
+++ b/include/trace/events/sched.h
@@ -107,6 +107,8 @@
#ifdef CREATE_TRACE_POINTS
static inline long __trace_sched_switch_state(bool preempt, struct task_struct *p)
{
+ unsigned int state;
+
#ifdef CONFIG_SCHED_DEBUG
BUG_ON(p != current);
#endif /* CONFIG_SCHED_DEBUG */
@@ -118,7 +120,15 @@ static inline long __trace_sched_switch_state(bool preempt, struct task_struct *
if (preempt)
return TASK_REPORT_MAX;
- return 1 << task_state_index(p);
+ /*
+ * task_state_index() uses fls() and returns a value from 0-8 range.
+ * Decrement it by 1 (except TASK_RUNNING state i.e 0) before using
+ * it for left shift operation to get the correct task->state
+ * mapping.
+ */
+ state = task_state_index(p);
+
+ return state ? (1 << (state - 1)) : state;
}
#endif /* CREATE_TRACE_POINTS */
--
Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.
next reply other threads:[~2018-10-30 6:54 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-30 6:54 Pavankumar Kondeti [this message]
2018-11-27 9:34 ` [PATCH] sched, trace: Fix prev_state output in sched_switch tracepoint Pavan Kondeti
2018-11-27 14:29 ` Steven Rostedt
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