Re: freezing of kernel threads

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Thu, Nov 22, 2012 at 11:21:30AM +0000, Jan Beulich wrote:
> Keir,
> 
> in linux-2.6.18-xen.hg c/s 74:cb50d25a9468 you made blktap
> match blkback in calling try_to_freeze() from the main thread loop.
> Threads in other drivers didn't get changed, though. Is there a
> particular reason why only block, and only backend, threads are in
> need of this (the only other one using it is xenfb_thread())?
> 
> Konrad, as of 2.6.23 kernel threads are non-freezable by default,
> i.e. xen-blkback calling try_to_freeze() is completely pointless
> without a prior call to set_freezable(). Also, in case the latter is to
> be added, switching to wait_event_freezable() instead of the
> direct use of try_to_freeze() might be the right way to go.

OK, any idea why the need to be come freezable was added in? Just
for power suspend/resume?

> 
> Jan
>