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Subject[PATCH AUTOSEL 4.19 09/47] firmware/psci: psci_checker: Park kthreads before stopping them
Date
From: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>

[ Upstream commit 92e074acf6f7694e96204265eb18ac113f546e80 ]

Since commit 85f1abe0019f ("kthread, sched/wait: Fix kthread_parkme()
completion issue"), kthreads that are bound to a CPU must be parked
before being stopped. At the moment the PSCI checker calls
kthread_stop() directly on the suspend kthread, which triggers the
following warning:

[ 6.068288] WARNING: CPU: 1 PID: 1 at kernel/kthread.c:398 __kthread_bind_mask+0x20/0x78
...
[ 6.190151] Call trace:
[ 6.192566] __kthread_bind_mask+0x20/0x78
[ 6.196615] kthread_unpark+0x74/0x80
[ 6.200235] kthread_stop+0x44/0x1d8
[ 6.203769] psci_checker+0x3bc/0x484
[ 6.207389] do_one_initcall+0x48/0x260
[ 6.211180] kernel_init_freeable+0x2c8/0x368
[ 6.215488] kernel_init+0x10/0x100
[ 6.218935] ret_from_fork+0x10/0x1c
[ 6.222467] ---[ end trace e05e22863d043cd3 ]---

kthread_unpark() tries to bind the thread to its CPU and aborts with a
WARN() if the thread wasn't in TASK_PARKED state. Park the kthreads
before stopping them.

Fixes: 85f1abe0019f ("kthread, sched/wait: Fix kthread_parkme() completion issue")
Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/firmware/psci_checker.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/firmware/psci_checker.c b/drivers/firmware/psci_checker.c
index 346943657962..cbd53cb1b2d4 100644
--- a/drivers/firmware/psci_checker.c
+++ b/drivers/firmware/psci_checker.c
@@ -366,16 +366,16 @@ static int suspend_test_thread(void *arg)
for (;;) {
/* Needs to be set first to avoid missing a wakeup. */
set_current_state(TASK_INTERRUPTIBLE);
- if (kthread_should_stop()) {
- __set_current_state(TASK_RUNNING);
+ if (kthread_should_park())
break;
- }
schedule();
}

pr_info("CPU %d suspend test results: success %d, shallow states %d, errors %d\n",
cpu, nb_suspend, nb_shallow_sleep, nb_err);

+ kthread_parkme();
+
return nb_err;
}

@@ -440,8 +440,10 @@ static int suspend_tests(void)


/* Stop and destroy all threads, get return status. */
- for (i = 0; i < nb_threads; ++i)
+ for (i = 0; i < nb_threads; ++i) {
+ err += kthread_park(threads[i]);
err += kthread_stop(threads[i]);
+ }
out:
cpuidle_resume_and_unlock();
kfree(threads);
--
2.20.1
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