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From: "Jason A. Donenfeld" <Jason@zx2c4.com>
To: Petr Mladek <pmladek@suse.com>
Cc: John Ogness <john.ogness@linutronix.de>,
	Marco Elver <elver@google.com>,
	linux-kernel@vger.kernel.org
Subject: Re: 5.19 printk breaks message ordering
Date: Fri, 17 Jun 2022 16:41:05 +0200	[thread overview]
Message-ID: <YqySgdH3sGj7o9O8@zx2c4.com> (raw)
In-Reply-To: <YqyN20jpRw1SaaTw@alley>

On Fri, Jun 17, 2022 at 04:21:15PM +0200, Petr Mladek wrote:
> In fact, in your case you might get even better synchronization
> if you do it the other way and write userspace messages into
> the kernel log via /dev/kmsg:
> 
>      echo "Hello world" > /dev/kmsg

The idea is to interleave stderr/stdout properly, as CI has done for
ages, which threaded printk breaks, and which my patch (now posted)
fixes behind a default-off option. You can't dup2 /dev/kmsg to 1 and 2,
as the write() semantics are different, with respect to buffering and
with respect to new lines. The interfaces aren't comparable, so this
isn't quite a solution. (Besides, not breaking things as they currently
exist has a certain benefit.)

Jason

  reply	other threads:[~2022-06-17 14:41 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-17 13:23 Jason A. Donenfeld
2022-06-17 13:37 ` Jason A. Donenfeld
2022-06-17 13:38   ` [PATCH] printk: allow direct console printing to be enabled always Jason A. Donenfeld
2022-06-19  0:30     ` Randy Dunlap
2022-06-19  8:37       ` Jason A. Donenfeld
2022-06-19 11:05     ` John Ogness
2022-06-19 20:39       ` Jason A. Donenfeld
2022-06-19 20:43         ` [PATCH v2] " Jason A. Donenfeld
2022-06-19 23:17           ` John Ogness
2022-06-19 23:28             ` Jason A. Donenfeld
2022-06-19 23:33               ` [PATCH v3] " Jason A. Donenfeld
2022-06-20 16:58                 ` Petr Mladek
2022-06-20 17:03                   ` Jason A. Donenfeld
2022-06-21  9:43                   ` David Laight
2022-06-21  9:59                 ` Jason A. Donenfeld
2022-06-22 12:55                   ` Jason A. Donenfeld
2022-06-20  4:04             ` [PATCH v2] " David Laight
2022-06-20  5:17             ` Sergey Senozhatsky
2022-06-20  7:56               ` Jason A. Donenfeld
2022-06-21  1:34                 ` Sergey Senozhatsky
2022-06-21 21:47               ` John Ogness
2022-06-17 14:21 ` 5.19 printk breaks message ordering Petr Mladek
2022-06-17 14:41   ` Jason A. Donenfeld [this message]
2022-06-17 15:01   ` David Laight
2022-06-19  8:15     ` John Ogness
2022-06-19 14:24       ` David Laight

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