Re: [Dle-develop] [PATCH] Avoid dead lock of console related locks in panic case

[Andrew M. <ak...@li...>]

On Fri, 30 Nov 2012 22:59:13 +0000
Seiji Aguchi <sei...@hd...> wrote:

> > 
> > Let's step back a bit.  Please identify with great specificity the code sites which are stopping other CPUs before taking locks which
> > those other CPUs might have been holding.
> > 
> > Then let's see what we can do to fix up the callers, instead of trying to tidy up after they have made this mess.
> 
> OK.
> I will update my patch without adding complexity.
> The logic will be as follows, if I understand your comment correctly.
> 
>  - take console related locks (logbuf_lock, console_sem)
>  - stop other cpus
>  - release those locks

That would be one way around the problem.  It's still a bit messy,
because we'll have to take more and more locks in the future, as we
identify them.

What I actually meant was: can "this" CPU avoid stopping other CPUs so
early?  If we stop the other CPUs when this CPU is ready to stop itself
then there will never be such deadlocks.