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From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: Byungchul Park <byungchul.park@lge.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Jan Kara <jack@suse.com>, Petr Mladek <pmladek@suse.com>,
	Tejun Heo <tj@kernel.org>,
	Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
	linux-kernel@vger.kernel.org, Jan Kara <jack@suse.cz>
Subject: Re: [RFC][PATCH v5 1/2] printk: Make printk() completely async
Date: Mon, 21 Mar 2016 17:51:34 +0900	[thread overview]
Message-ID: <20160321085134.GA504@swordfish> (raw)
In-Reply-To: <20160321080751.GA2279@X58A-UD3R>

On (03/21/16 17:07), Byungchul Park wrote:
[..]
> > > > > It will not print the "lockup suspected" message at all, for e.g. rq->lock,
> > > > > p->pi_lock and any locks which are used within wake_up_process().
> > > > 
> > > > this will switch to old SYNC printk() mode should such a lockup ever
> > > > happen, which is a giant advantage over any other implementation; doing
> > > > wake_up_process() within the 'we can detect recursive printk() here'
> > > > gives us better control.
> > > > 
> > > > why
> > > >   printk()->IRQ->wake_up_process()->spin_dump()->printk()->IRQ->wake_up_process()->spin_dump()->printk()->IRQ...
> > > > is better?
> > > 
> > > What is IRQ?
> > 
> > this is how printk() can print the messages in async mode apart from
> > direct and wake_up_process() in vprintk_emit().
> 
> Do you mean IRQ work?

yes.

> Is there any reason why you don't put the wake_up_process() out of the
> critical section

I provided reasons already.

> with my suggestion, even though it can solve the infinite recuresion you worried about?

which is 'a static lock pointer in spin_dump()'? I don't think
this will fix recursive printks.



/* seems that for some reason my previous reply was not delivered. re-sending. */

	-ss

  parent reply	other threads:[~2016-03-21  8:50 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-03-20 14:13 [RFC][PATCH v5 0/2] printk: Make printk() completely async Sergey Senozhatsky
2016-03-20 14:13 ` [RFC][PATCH v5 1/2] " Sergey Senozhatsky
2016-03-21  0:06   ` Byungchul Park
2016-03-21  0:43     ` Sergey Senozhatsky
2016-03-21  0:56       ` Byungchul Park
2016-03-21  7:35         ` Sergey Senozhatsky
2016-03-21  8:07           ` Byungchul Park
2016-03-21  8:47             ` Byungchul Park
2016-03-21  9:28               ` Sergey Senozhatsky
2016-03-21 14:32                 ` Jan Kara
2016-03-21 14:58                   ` Sergey Senozhatsky
2016-03-21 15:33                     ` Jan Kara
2016-03-21 17:11                       ` Sergey Senozhatsky
2016-03-22  2:18                         ` Byungchul Park
2016-03-22  2:13                 ` Byungchul Park
2016-03-22  5:52                   ` Sergey Senozhatsky
2016-03-22  6:57                     ` Byungchul Park
2016-03-22  7:43                       ` Sergey Senozhatsky
2016-03-21  8:51             ` Sergey Senozhatsky [this message]
2016-03-20 14:13 ` [RFC][PATCH v5 2/2] printk: Make wake_up_klogd_work_func() async Sergey Senozhatsky

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