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| author | Valentin Schneider <valentin.schneider@arm.com> | 2022-01-20 16:25:19 +0000 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2022-03-01 16:18:39 +0100 |
| commit | fa2c3254d7cfff5f7a916ab928a562d1165f17bb (patch) | |
| tree | 678cc10a62564212f526fc4a65ea345fde95794e /kernel/sched/core.c | |
| parent | 49bef33e4b87b743495627a529029156c6e09530 (diff) | |
| download | lwn-fa2c3254d7cfff5f7a916ab928a562d1165f17bb.tar.gz lwn-fa2c3254d7cfff5f7a916ab928a562d1165f17bb.zip | |
sched/tracing: Don't re-read p->state when emitting sched_switch event
As of commit
c6e7bd7afaeb ("sched/core: Optimize ttwu() spinning on p->on_cpu")
the following sequence becomes possible:
p->__state = TASK_INTERRUPTIBLE;
__schedule()
deactivate_task(p);
ttwu()
READ !p->on_rq
p->__state=TASK_WAKING
trace_sched_switch()
__trace_sched_switch_state()
task_state_index()
return 0;
TASK_WAKING isn't in TASK_REPORT, so the task appears as TASK_RUNNING in
the trace event.
Prevent this by pushing the value read from __schedule() down the trace
event.
Reported-by: Abhijeet Dharmapurikar <adharmap@quicinc.com>
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Link: https://lore.kernel.org/r/20220120162520.570782-2-valentin.schneider@arm.com
Diffstat (limited to 'kernel/sched/core.c')
| -rw-r--r-- | kernel/sched/core.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index ef946123e9af..3aafc15da24a 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -4836,7 +4836,7 @@ static struct rq *finish_task_switch(struct task_struct *prev) { struct rq *rq = this_rq(); struct mm_struct *mm = rq->prev_mm; - long prev_state; + unsigned int prev_state; /* * The previous task will have left us with a preempt_count of 2 @@ -6300,7 +6300,7 @@ static void __sched notrace __schedule(unsigned int sched_mode) migrate_disable_switch(rq, prev); psi_sched_switch(prev, next, !task_on_rq_queued(prev)); - trace_sched_switch(sched_mode & SM_MASK_PREEMPT, prev, next); + trace_sched_switch(sched_mode & SM_MASK_PREEMPT, prev_state, prev, next); /* Also unlocks the rq: */ rq = context_switch(rq, prev, next, &rf); |