From: Peter Zijlstra <peterz@infradead.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Greg KH <greg@kroah.com>, "Theodore Ts'o" <tytso@mit.edu>,
Alan Cox <alan@lxorguk.ukuu.org.uk>,
linux-kernel <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@elte.hu>
Subject: Re: printk() vs tty_io
Date: Wed, 14 Dec 2011 10:38:08 +0100 [thread overview]
Message-ID: <1323855488.28489.16.camel@twins> (raw)
In-Reply-To: <CA+55aFxNWiRQ1CkifhgcnnBqBa-xRNdM9Ze6bnxhsYd4ZYPg6A@mail.gmail.com>
On Tue, 2011-12-13 at 15:52 -0800, Linus Torvalds wrote:
> On Tue, Dec 13, 2011 at 11:33 AM, Peter Zijlstra <peterz@infradead.org> wrote:
> >
> > I've been poking at reducing the constraints on printk(), like make it
> > work under rq->lock etc..
>
> You aren't supposed register a console that wakes things up. But the
> only console that honors that afaik is the traditional vt console.
> *Maybe* the network console, I didn't check.
>
> I *assume* you only get this lockdep warning if you have a serial console?
I only ever use serial, I'll try and have a go at reproducing any of
this on a machine that actually has a screen attached.
Anyway, would it make any sense to start enforcing this 'rule'? Can we
reasonably make the serial stuff not wake things? Let alone the
fbdev/ksm consoles that seem popular these days.
Thing is, if everybody and their dog are using ksm, and we cannot make
ksm console wake-free, there's a very limited point to my endeavor to
make printk() work under rq->lock etc..
next prev parent reply other threads:[~2011-12-14 9:39 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-13 19:33 printk() vs tty_io Peter Zijlstra
2011-12-13 23:52 ` Linus Torvalds
2011-12-14 9:38 ` Peter Zijlstra [this message]
2011-12-14 10:43 ` Alan Cox
2011-12-14 10:56 ` Peter Zijlstra
2011-12-14 14:05 ` Ted Ts'o
2011-12-14 14:23 ` Peter Zijlstra
2011-12-14 15:54 ` Linus Torvalds
2011-12-15 9:56 ` Peter Zijlstra
2011-12-15 10:32 ` Alan Cox
2011-12-15 10:55 ` Peter Zijlstra
2011-12-15 17:08 ` Linus Torvalds
2011-12-15 18:07 ` Ingo Molnar
2011-12-15 21:22 ` Alan Cox
2011-12-16 13:25 ` Peter Zijlstra
2011-12-15 19:02 ` Greg KH
2011-12-14 6:59 ` Ingo Molnar
2011-12-14 9:40 ` [PATCH] arch, early_printk: Consolidate early_printk() implementations Peter Zijlstra
2011-12-14 9:41 ` [PATCH] lockdep: Enable earlyprintk output Peter Zijlstra
2011-12-14 9:43 ` printk() vs tty_io Peter Zijlstra
2011-12-14 9:46 ` Ingo Molnar
2011-12-21 12:03 ` Stijn Devriendt
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