Re: [PATCH] migrate_disable pushd down in rt_read_trylock

[Nicholas Mc Guire <der.herr@hofr.at>]

On Sun, 15 Dec 2013, Sebastian Andrzej Siewior wrote:

> * Nicholas Mc Guire | 2013-11-30 07:47:55 [+0100]:
> 
> >given that the broken patch was disabling once and enabling potentially a
> >number of times it should have triggert the
> >WARN_ON_ONCE(p->migrate_disable <= 0); in migrate_enable() if the recursive
> >case would have ever bin hit... so much to testing and locking...
> 
> And is why I removed the line
> > No change of functionality
> 
> from the change log because it was not obvious to me that is a
> zero-change patch :)

well that was the intent and obviously
it was not the case - so it served its purpose
to document the intent.

> 
> Are you going to redo this one?
>
no - as David Miller stated clearly that he sees these
split-api locks as a valid idiom and there were clear
worries that this would break in the future I see no point
in pushing this. The alternative of removing the recursive
migrate_disable/enable in local_bh_* directly is good
enough I guess - see: 
0001-make-migrate-disable-enable-conditioned-on-softirq_n.patch

thx!
hofrat