Messages in this thread Patch in this message | | | From | Uwe Kleine-König <> | Subject | [PATCH] siox: don't create a thread without starting it | Date | Thu, 28 Jun 2018 09:57:42 +0200 |
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When a siox master device is registered a kthread is created that is only started when triggered by userspace. So this thread might be in TASK_UNINTERRUPTIBLE state for long and trigger a warning
[ 241.130465] INFO: task siox-0:626 blocked for more than 120 seconds.
with the respective debug settings enabled. It might be right to put an unstarted thread to TASK_IDLE (in kernel/kthread.c:kthread()) instead, but independant of this discussion it is cleaner for siox_master_register() to start the thread immediately. The effect is that it enters its own waiting state and then stays in state TASK_IDLE which doesn't trigger the above warning.
As siox_poll_thread() uses some variables of the device the initialisation of these is moved before thread creation.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> --- Hello,
this is the same patch as before with an updated commit log. I added Peter's ack anyhow assuming my text isn't too bad to make him withdraw it.
I think this issue isn't critical as the machine works fine otherwise, so applying it for 4.18-rc isn't necessary. (OTOH it's an SMP machine so the tests might not have noticed one blocked CPU, didn't test this.)
Greg, you applied the initial patches creating drivers/siox. I assume you will continue to apply siox patches and tell if I should search a different path for these.
Best regards Uwe
drivers/siox/siox-core.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/drivers/siox/siox-core.c b/drivers/siox/siox-core.c index 16590dfaafa4..cef307c0399c 100644 --- a/drivers/siox/siox-core.c +++ b/drivers/siox/siox-core.c @@ -715,17 +715,17 @@ int siox_master_register(struct siox_master *smaster) dev_set_name(&smaster->dev, "siox-%d", smaster->busno); + mutex_init(&smaster->lock); + INIT_LIST_HEAD(&smaster->devices); + smaster->last_poll = jiffies; - smaster->poll_thread = kthread_create(siox_poll_thread, smaster, - "siox-%d", smaster->busno); + smaster->poll_thread = kthread_run(siox_poll_thread, smaster, + "siox-%d", smaster->busno); if (IS_ERR(smaster->poll_thread)) { smaster->active = 0; return PTR_ERR(smaster->poll_thread); } - mutex_init(&smaster->lock); - INIT_LIST_HEAD(&smaster->devices); - ret = device_add(&smaster->dev); if (ret) kthread_stop(smaster->poll_thread); -- 2.18.0
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