Re: printk() vs tty_io

From: Ingo Molnar
Date: Wed Dec 14 2011 - 02:01:13 EST


* Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:

> Hi tty folks,
>
> I've been poking at reducing the constraints on printk(), like make it
> work under rq->lock etc..
>
> Aside from a fwd port of the patch that abuses the
> console_sem.lock: https://lkml.org/lkml/2011/6/9/298 and a few
> other not so very pretty patches, I ran into the following
> lockdep splat (using a not so very pretty lockdep
> early_printk() patch):

btw., would be nice to also somehow realeasify those debug hacks
to preserve them for eternity - doing all lockdep output as
earlyprintk while keeping printks working is a great way to
debug printk() itself.

Those printk lockups also took a *lot* of time for me to bisect.

Thanks,

Ingo
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