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From: David Laight <David.Laight@ACULAB.COM>
To: 'Petr Mladek' <pmladek@suse.com>,
	John Ogness <john.ogness@linutronix.de>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	Jiri Slaby <jirislaby@kernel.org>,
	"Paul E. McKenney" <paulmck@kernel.org>,
	"Josh Triplett" <josh@joshtriplett.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Lai Jiangshan <jiangshanlai@gmail.com>,
	Joel Fernandes <joel@joelfernandes.org>,
	Corey Minyard <cminyard@mvista.com>,
	Kees Cook <keescook@chromium.org>,
	Christian Brauner <christian.brauner@ubuntu.com>,
	Daniel Bristot de Oliveira <bristot@redhat.com>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
	Mark Brown <broonie@kernel.org>,
	Josef Bacik <josef@toxicpanda.com>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	"Shawn Guo" <shawn.guo@linaro.org>,
	Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Wang Qing <wangqing@vivo.com>, Tejun Heo <tj@kernel.org>,
	Randy Dunlap <rdunlap@infradead.org>,
	Alexander Potapenko <glider@google.com>,
	Stephen Boyd <sboyd@kernel.org>,
	Nicholas Piggin <npiggin@gmail.com>,
	"rcu@vger.kernel.org" <rcu@vger.kernel.org>
Subject: RE: [PATCH printk v1 09/13] printk: add functions to allow direct printing
Date: Fri, 18 Feb 2022 09:00:46 +0000	[thread overview]
Message-ID: <ca5b7ec96aa444c292b3413a6374028b@AcuMS.aculab.com> (raw)
In-Reply-To: <Yg5FCVF5c1jDo116@alley>

> On Mon 2022-02-07 20:49:19, John Ogness wrote:
> > Once kthread printing is introduced, console printing will no longer
> > occur in the context of the printk caller. However, there are some
> > special contexts where it is desirable for the printk caller to
> > directly print out kernel messages.

Yes - most of them.

It is going to be pretty impossible to do 'hard' kernel debugging
if printk get deferred.

Typically there already is a deferral method.
The prints aren't done by the kernel, but by syslogd.

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)


  reply	other threads:[~2022-02-18  9:00 UTC|newest]

Thread overview: 87+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-07 19:43 [PATCH printk v1 00/13] implement threaded console printing John Ogness
2022-02-07 19:43 ` [PATCH printk v1 01/13] printk: rename cpulock functions John Ogness
2022-02-11 12:44   ` Petr Mladek
2022-02-11 14:42     ` John Ogness
2022-02-11 20:57       ` Steven Rostedt
2022-02-11 21:04         ` Peter Zijlstra
2022-02-15  9:32           ` Petr Mladek
2022-02-15  9:13       ` Petr Mladek
2022-02-14  6:49     ` Sergey Senozhatsky
2022-02-14  9:45       ` John Ogness
2022-02-15  9:29       ` Petr Mladek
2022-02-16  3:27         ` Sergey Senozhatsky
2022-02-17 14:34         ` John Ogness
2022-02-07 19:43 ` [PATCH printk v1 02/13] printk: cpu sync always disable interrupts John Ogness
2022-02-11 12:58   ` Petr Mladek
2022-02-14  6:36     ` Sergey Senozhatsky
2022-02-07 19:43 ` [PATCH printk v1 03/13] printk: use percpu flag instead of cpu_online() John Ogness
2022-02-11 16:05   ` Petr Mladek
2022-02-14  7:08     ` Sergey Senozhatsky
2022-02-14  7:35     ` Sergey Senozhatsky
2022-02-15 10:38       ` Petr Mladek
2022-02-16  3:29         ` Sergey Senozhatsky
2022-03-02 14:21         ` John Ogness
2022-03-04 15:56           ` Petr Mladek
2022-03-05 17:05             ` Jason A. Donenfeld
2022-03-07 16:14               ` Petr Mladek
2022-02-16 13:58   ` two locations: was: " Petr Mladek
2022-03-02 14:49     ` John Ogness
2022-03-04 16:14       ` Petr Mladek
2022-03-07 10:06         ` John Ogness
2022-03-08 16:08       ` Petr Mladek
2022-02-07 19:43 ` [PATCH printk v1 04/13] printk: get caller_id/timestamp after migration disable John Ogness
2022-02-15  5:53   ` Sergey Senozhatsky
2022-02-15 11:56   ` Petr Mladek
2022-02-07 19:43 ` [PATCH printk v1 05/13] printk: call boot_delay_msec() in printk_delay() John Ogness
2022-02-15  5:58   ` Sergey Senozhatsky
2022-02-15 14:59     ` Petr Mladek
2022-02-16  3:21       ` Sergey Senozhatsky
2022-02-15 15:03   ` Petr Mladek
2022-02-07 19:43 ` [PATCH printk v1 06/13] printk: refactor and rework printing logic John Ogness
2022-02-16 15:43   ` Petr Mladek
2022-03-02 16:10     ` John Ogness
2022-02-07 19:43 ` [PATCH printk v1 07/13] printk: move buffer definitions into console_emit_next_record() caller John Ogness
2022-02-16 16:10   ` Petr Mladek
2022-03-02 16:25     ` John Ogness
2022-02-07 19:43 ` [PATCH printk v1 08/13] printk: add pr_flush() John Ogness
2022-02-17 10:11   ` Petr Mladek
2022-03-02 17:23     ` John Ogness
2022-03-04 13:24       ` Petr Mladek
2022-02-07 19:43 ` [PATCH printk v1 09/13] printk: add functions to allow direct printing John Ogness
2022-02-17 12:52   ` Petr Mladek
2022-02-18  9:00     ` David Laight [this message]
2022-02-18 12:52       ` Petr Mladek
2022-03-03 14:37     ` John Ogness
2022-02-07 19:43 ` [PATCH printk v1 10/13] printk: add kthread console printers John Ogness
2022-02-18  9:00   ` early start: was: " Petr Mladek
2022-02-18  9:04   ` start&stop: " Petr Mladek
2022-02-18  9:08   ` main loop: " Petr Mladek
2022-02-18  9:12   ` wake_up_all: " Petr Mladek
2022-02-07 19:43 ` [PATCH printk v1 11/13] printk: reimplement console_lock for proper kthread support John Ogness
2022-02-18 16:20   ` Petr Mladek
2022-02-18 21:41     ` John Ogness
2022-02-18 22:03       ` John Ogness
2022-02-22 11:42       ` Petr Mladek
2022-02-23 17:20         ` John Ogness
2022-02-24  8:27           ` Petr Mladek
2022-02-23 10:19   ` Petr Mladek
2022-03-09 13:56     ` John Ogness
2022-03-10 14:34       ` Petr Mladek
2022-03-10 16:08         ` John Ogness
2022-03-11 10:26           ` Petr Mladek
2022-03-11 13:28             ` John Ogness
2022-03-11 16:17               ` Petr Mladek
2022-03-11 22:21                 ` John Ogness
2022-03-14 14:08                   ` Petr Mladek
2022-03-14 14:43                     ` John Ogness
2022-03-14 15:53                       ` Petr Mladek
2022-03-11 18:41               ` Petr Mladek
2022-02-07 19:43 ` [PATCH printk v1 12/13] printk: remove @console_locked John Ogness
2022-02-23 12:17   ` Petr Mladek
2022-02-07 19:43 ` [PATCH printk v1 13/13] console: introduce CON_MIGHT_SLEEP for vt John Ogness
2022-02-23 13:37   ` Petr Mladek
2022-02-23 18:31     ` Greg Kroah-Hartman
     [not found] ` <20220208083620.2736-1-hdanton@sina.com>
2022-02-08 11:08   ` [PATCH printk v1 10/13] printk: add kthread console printers John Ogness
2022-02-08 14:53     ` Petr Mladek
2022-02-14  6:12       ` Sergey Senozhatsky
2022-02-14 10:02         ` Petr Mladek

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