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Subjectis printk() safe within a timekeeper_seq write section?
Hi,

I'm looking at the printk call in
__timekeeping_inject_sleeptime(), introduced in cb5de2f8
(time: Catch invalid timespec sleep values in __timekeeping_inject_sleeptime)

Is it safe to call printk() while timekeeper_seq is held for
writing?

What about this call chain?
printk
vprintk_emit
console_unlock
up(&console_sem)
__up
wake_up_process
try_to_wake_up
ttwu_do_activate
ttwu_activate
activate_task
enqueue_task
enqueue_task_fair
hrtick_update
hrtick_start_fair
hrtick_start_fair
get_time
ktime_get
--> endless loop on
read_seqcount_retry(&timekeeper_seq, ...)


It looks like an unlikely but possible deadlock.
Or did I overlook something?

Thanks!

--
Jiri Bohac <jbohac@suse.cz>
SUSE Labs, SUSE CZ



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