Re: [linux-pm] Is it supposed to be ok to call del_gendisk whileuserspace is frozen?

From: Pavel Machek
Date: Thu Mar 04 2010 - 15:15:59 EST


> > My thought exactly. This is the only approach that also solves the
> > following race:
> >
> > A driver is unloaded at the same time as a suspend starts.
> >
> > The writeback thread gets frozen.
> >
> > Then before the rmmod thread is frozen, it calls del_gendisk.
> >
> > Delaying things by means of a workqueue (or the equivalent) might also
> > work, but it doesn't seem as safe. For example, some important
> > writebacks might end up getting delayed until too late.

Delaying writebacks during sleep should be ok... That's why we do
sync() after userspace is frozen -- nothing really important should be
waiting for writeback after that point.
(cesky, pictures)
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