linux-kernel - Re: [RFC][PATCHv3 2/5] printk: introduce printing kernel thread

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Date:   Fri, 30 Jun 2017 21:35:28 +0900
From:   Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
To:     sergey.senozhatsky.work@...il.com
Cc:     pmladek@...e.com, sergey.senozhatsky@...il.com,
        rostedt@...dmis.org, jack@...e.cz, akpm@...ux-foundation.org,
        peterz@...radead.org, rjw@...ysocki.net, ebiederm@...ssion.com,
        gregkh@...uxfoundation.org, jslaby@...e.com, pavel@....cz,
        andi@...as.de, linux-kernel@...r.kernel.org
Subject: Re: [RFC][PATCHv3 2/5] printk: introduce printing kernel thread

Sergey Senozhatsky wrote:
> On (06/30/17 19:18), Tetsuo Handa wrote:
> > > I'm still thinking about Steven's proposals; but we will need offloading
> > > anyways, so the bits we are talking about here are important regardless
> > > the direction printk design will take, I think.
> > 
> > Is there a chance that printk() waits for only data queued by that printk()
> > call (exception will be printk() from NMI).
> 
> hm, I don't think this can be done easily... consider
> 
> 	console_lock();
> 	printk();
> 	printk();
> 	...			-> this guys will wait forever. nothing
> 				   flushes the logbuf.
> 	printk();
> 	console_unlock();

Can't we remove console_lock()/console_unlock() from printk() ?
I think that printk() depends on console_unlock() is complicating.