Messages in this thread Patch in this message | | | From | Pavankumar Kondeti <> | Subject | [PATCH] sched, trace: Fix prev_state output in sched_switch tracepoint | Date | Tue, 30 Oct 2018 12:24:33 +0530 |
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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.
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