On a machine with a siox device I see:
[ 241.130465] INFO: task siox-0:626 blocked for more than 120 seconds.
[ 241.136996] Not tainted 4.17.0-20180520-1-g6248d1b64190-dirty
#8
[ 241.146831] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs"
disables this message.
[ 241.154868] siox-0 D 0 626 2 0x00000000
[ 241.163241] [<c05f8430>] (__schedule) from [<c05f88ec>]
(schedule+0x58/0xc8)
[ 241.172142] [<c05f88ec>] (schedule) from [<c0039098>]
(kthread+0xc4/0x140)
[ 241.180899] [<c0039098>] (kthread) from [<c00090e0>]
(ret_from_fork+0x14/0x34)
[ 241.188315] Exception stack(0xc72a7fb0 to 0xc72a7ff8)
[ 241.196327] 7fa0: 00000000
00000000 00000000 00000000
[ 241.204721] 7fc0: 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000
[ 241.215861] 7fe0: 00000000 00000000 00000000 00000000 00000013
00000000
when I just boot without any other siox-related action. So the kthread (created
in drivers/siox/siox-core.c:siox_master_register()) is never started.
While you could argue that there is little reason to not start the
thread there also is little reason to actually do it.
peterz in #kernelnewbies said "[...] kernel/kthread.c:kthread() should
really be using __set_current_state(TASK_IDLE), I suppose". This however
seems to interfere with problems fixed in a076e4bca2fd ("freezer: fix
kthread_create vs freezer theoretical race").
So I wonder where the real problem is and how it can be fixed.
Explicitly-not-signed-off-for-discussion-by: Uwe Kleine-König
<u.kleine-koe...@pengutronix.de>
---
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);
--
2.17.1
