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author | Valentin Schneider <valentin.schneider@arm.com> | 2022-01-20 17:25:20 +0100 |
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committer | Peter Zijlstra <peterz@infradead.org> | 2022-03-01 16:18:39 +0100 |
commit | 25795ef6299f07ce3838f3253a9cb34f64efcfae (patch) | |
tree | 8ca2a13144dc04b95650cccff0bd0ff6b5dc6814 | |
parent | sched/tracing: Don't re-read p->state when emitting sched_switch event (diff) | |
download | linux-25795ef6299f07ce3838f3253a9cb34f64efcfae.tar.xz linux-25795ef6299f07ce3838f3253a9cb34f64efcfae.zip |
sched/tracing: Report TASK_RTLOCK_WAIT tasks as TASK_UNINTERRUPTIBLE
TASK_RTLOCK_WAIT currently isn't part of TASK_REPORT, thus a task blocking
on an rtlock will appear as having a task state == 0, IOW TASK_RUNNING.
The actual state is saved in p->saved_state, but reading it after reading
p->__state has a few issues:
o that could still be TASK_RUNNING in the case of e.g. rt_spin_lock
o ttwu_state_match() might have changed that to TASK_RUNNING
As pointed out by Eric, adding TASK_RTLOCK_WAIT to TASK_REPORT implies
exposing a new state to userspace tools which way not know what to do with
them. The only information that needs to be conveyed here is that a task is
waiting on an rt_mutex, which matches TASK_UNINTERRUPTIBLE - there's no
need for a new state.
Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
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/20220120162520.570782-3-valentin.schneider@arm.com
-rw-r--r-- | include/linux/sched.h | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index 457c8a058b77..78b606c9ab38 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1630,6 +1630,14 @@ static inline unsigned int __task_state_index(unsigned int tsk_state, if (tsk_state == TASK_IDLE) state = TASK_REPORT_IDLE; + /* + * We're lying here, but rather than expose a completely new task state + * to userspace, we can make this appear as if the task has gone through + * a regular rt_mutex_lock() call. + */ + if (tsk_state == TASK_RTLOCK_WAIT) + state = TASK_UNINTERRUPTIBLE; + return fls(state); } |