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From: Petr Mladek <pmladek@suse.com>
To: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>, Jan Kara <jack@suse.cz>,
	Andrew Morton <akpm@linux-foundation.org>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Jan Kara <jack@suse.com>, Tejun Heo <tj@kernel.org>,
	Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Byungchul Park <byungchul.park@lge.com>,
	vlevenetz@mm-sol.com,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [PATCH v10 1/2] printk: Make printk() completely async
Date: Thu, 18 Aug 2016 12:56:29 +0200	[thread overview]
Message-ID: <20160818105629.GE26194@pathway.suse.cz> (raw)
In-Reply-To: <20160818095144.GA425@swordfish>

On Thu 2016-08-18 18:51:44, Sergey Senozhatsky wrote:
> On (08/18/16 11:33), Petr Mladek wrote:
> [..]
> > > > 2. Force synchronous printk inside WARN()/BUG() macros.
> > > 
> > > will it help? semaphore up() calls wake_up_process() regardless the context.
> > > not to mention that we still may have spin_dump() enabled.
> > 
> > Good point. That changes my preferences :-)
> > 
> > > 
> > > > 3. Force printk_deferred() inside WARN()/BUG() macros via the per-CPU
> > > >    printk_func.
> > > > 
> > > >    It might be elegant. But we do not want this outside the scheduler
> > > >    code. Therefore we would need special variants of  WARN_*_SCHED()
> > > >    BUG_*_SCHED() macros.
> > 
> > Also we need to make sure that everything will be done on a single CPU
> > as the printk_func is per-CPU variable.
> 
> lib/dump_stack.c dump_stack() disables local IRQs, so we will stay
> on the same CPU.

It is less important to stay of the same CPU if you use
printk_deferred() directly. But it us must to have if you
use it via the printk_func per-CPU variable.

The advantage of the printk_func trick is that it is transparent.
You do not need to modify any existing functions used by WARN()/BUG()
macros.

Best Regards,
Petr

  reply	other threads:[~2016-08-18 10:56 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-04-04 16:57 [PATCH v10 0/2] printk: Make printk() completely async Sergey Senozhatsky
2016-04-04 16:57 ` [PATCH v10 1/2] " Sergey Senozhatsky
2016-04-04 22:51   ` Andrew Morton
2016-04-05  5:17     ` Sergey Senozhatsky
2016-04-05  7:39       ` Sergey Senozhatsky
2016-04-06  0:19         ` Sergey Senozhatsky
2016-04-06  8:27     ` Jan Kara
2016-04-07  9:48       ` Sergey Senozhatsky
2016-04-07 12:08         ` Sergey Senozhatsky
2016-04-07 13:15           ` Jan Kara
2016-08-10 21:17       ` Viresh Kumar
2016-08-12  9:44         ` Petr Mladek
2016-08-15 14:26           ` Vladislav Levenetz
2016-08-16  9:04             ` Petr Mladek
2016-08-18  2:27           ` Sergey Senozhatsky
2016-08-18  9:33             ` Petr Mladek
2016-08-18  9:51               ` Sergey Senozhatsky
2016-08-18 10:56                 ` Petr Mladek [this message]
2016-08-19  6:32                   ` Sergey Senozhatsky
2016-08-19  9:54                     ` Petr Mladek
2016-08-19 19:00                       ` Jan Kara
2016-08-20  5:24                         ` Sergey Senozhatsky
2016-08-22  4:15                           ` Sergey Senozhatsky
2016-08-23 12:19                             ` Petr Mladek
2016-08-24  1:33                               ` Sergey Senozhatsky
2016-08-25 21:10                             ` Petr Mladek
2016-08-26  1:56                               ` Sergey Senozhatsky
2016-08-26  8:20                                 ` Sergey Senozhatsky
2016-08-30  9:29                                 ` Petr Mladek
2016-08-31  2:31                                   ` Sergey Senozhatsky
2016-08-31  9:38                                     ` Petr Mladek
2016-08-31 12:52                                       ` Sergey Senozhatsky
2016-09-01  8:58                                         ` Petr Mladek
2016-09-02  7:58                                           ` Sergey Senozhatsky
2016-09-02 15:15                                             ` Petr Mladek
2016-09-06  7:16                                               ` Sergey Senozhatsky
2016-08-23 13:03                           ` Petr Mladek
2016-08-23 13:48                         ` Petr Mladek
2016-04-04 16:57 ` [PATCH v10 2/2] printk: Make wake_up_klogd_work_func() async Sergey Senozhatsky
2016-08-23  3:32 [PATCH v10 1/2] printk: Make printk() completely async Andreas Mohr

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