Messages in this thread | | | Date | Thu, 16 Aug 2007 20:03:09 +0400 | From | Oleg Nesterov <> | Subject | Re: [PATCH 3/3] tty_io.c: don't use flush_scheduled_work() |
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On 08/16, Dan Aloni wrote: > > On Sun, Jul 01, 2007 at 07:37:49PM +0400, Oleg Nesterov wrote: > > I don't know how to test this patch, the ack/nack from maintainer is wanted. > > > > flush_scheduled_work() is evil and should be avoided. Change tty_set_ldisc() > > and release_dev() to use cancel_delayed_work_sync/cancel_work_sync. > > > > I am not sure we really need to call do_tty_hangup() when cancel_work_sync() > > returns true, but this matches the current behaviour. > > I also noticed this problem recently with 2.6.22, on a 2-CPU box where there > was one SCHED_RR userspace process stuck in a busy loop. The box was completely > responsive but had this annoyance where all tty closings were stuck in > flush_scheduled_work(). It's especially noticable when you ssh to the machine > and then try to log out.
cancel_work_sync(work) can hang too if some SCHED_RR userspace process does not relinquish CPU, but the probability is much lower (it should preempt work->func of that work_struct).
see also http://marc.info/?l=linux-kernel&m=118115098120503.
Oleg.
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