From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Petr Mladek <pmladek@suse.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
John Ogness <john.ogness@linutronix.de>,
Linus Torvalds <torvalds@linux-foundation.org>,
Guenter Roeck <linux@roeck-us.net>,
Shreyas Joshi <shreyas.joshi@biamp.com>,
shreyasjoshi15@gmail.com,
Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] init/console: Use ttynull as a fallback when there is no console
Date: Wed, 11 Nov 2020 17:36:34 +0100 [thread overview]
Message-ID: <X6wTEpJwC+ZoLSAy@kroah.com> (raw)
In-Reply-To: <20201111135450.11214-2-pmladek@suse.com>
On Wed, Nov 11, 2020 at 02:54:49PM +0100, Petr Mladek wrote:
> stdin, stdout, and stderr standard I/O stream are created for the init
> process. They are not available when there is no console registered
> for /dev/console. It might lead to a crash when the init process
> tries to use them, see the commit 48021f98130880dd742 ("printk: handle
> blank console arguments passed in.").
>
> Normally, ttySX and ttyX consoles are used as a fallback when no consoles
> are defined via the command line, device tree, or SPCR. But there
> will be no console registered when an invalid console name is configured
> or when the configured consoles do not exist on the system.
>
> Users even try to avoid the console intentionally, for example,
> by using console="" or console=null. It is used on production
> systems where the serial port or terminal are not visible to
> users. Pushing messages to these consoles would just unnecessary
> slowdown the system.
>
> Make sure that stdin, stdout, stderr, and /dev/console are always
> available by a fallback to the existing ttynull driver. It has
> been implemented for exactly this purpose but it was used only
> when explicitly configured.
>
> Signed-off-by: Petr Mladek <pmladek@suse.com>
Tricky, and nice to use the existing driver for this, I like it:
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
next prev parent reply other threads:[~2020-11-11 16:35 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-11 13:54 [PATCH 0/2] printk/console: Use ttynull when no console is available or wanted Petr Mladek
2020-11-11 13:54 ` [PATCH 1/2] init/console: Use ttynull as a fallback when there is no console Petr Mladek
2020-11-11 16:36 ` Greg Kroah-Hartman [this message]
2020-11-11 22:52 ` Guenter Roeck
2020-11-11 23:58 ` Sergey Senozhatsky
2020-11-12 0:17 ` Sergey Senozhatsky
2020-11-12 1:45 ` Sergey Senozhatsky
2020-11-16 16:20 ` Petr Mladek
2021-01-06 23:36 ` ARC no console output (was Re: [PATCH 1/2] init/console: Use ttynull as a fallback when there is no console) Vineet Gupta
2021-01-06 23:36 ` Vineet Gupta
2021-01-06 23:36 ` [Buildroot] " Vineet Gupta
2021-01-07 9:02 ` John Ogness
2021-01-07 9:02 ` John Ogness
2021-01-07 13:14 ` Greg Ungerer
2021-01-07 13:14 ` Greg Ungerer
2021-01-07 16:43 ` Vineet Gupta
2021-01-07 16:43 ` Vineet Gupta
2021-01-07 16:43 ` [Buildroot] " Vineet Gupta
2021-01-07 17:04 ` Petr Mladek
2021-01-07 17:04 ` Petr Mladek
2021-01-07 17:58 ` Vineet Gupta
2021-01-07 17:58 ` Vineet Gupta
2021-01-07 17:58 ` [Buildroot] " Vineet Gupta
2021-01-08 3:48 ` Sergey Senozhatsky
2021-01-08 3:48 ` Sergey Senozhatsky
2021-01-08 5:18 ` Vineet Gupta
2021-01-08 5:18 ` Vineet Gupta
2021-01-08 5:18 ` [Buildroot] " Vineet Gupta
2021-01-08 9:30 ` Petr Mladek
2021-01-08 9:30 ` Petr Mladek
2021-01-13 22:07 ` Peter Korsgaard
2021-01-13 22:07 ` Peter Korsgaard
2021-01-13 22:07 ` [Buildroot] " Peter Korsgaard
2021-01-07 9:09 ` Richard Weinberger
2021-01-07 9:09 ` Richard Weinberger
2021-01-07 12:48 ` Petr Mladek
2021-01-07 12:48 ` Petr Mladek
2021-01-07 15:27 ` [Buildroot] " Yann E. MORIN
2021-01-07 15:27 ` Yann E. MORIN
2021-01-07 15:27 ` Yann E. MORIN
2020-11-11 13:54 ` [PATCH 2/2] printk/console: Allow to disable console output by using console="" or console=null Petr Mladek
2020-11-11 22:52 ` Guenter Roeck
2020-11-11 23:59 ` Sergey Senozhatsky
2020-11-20 14:24 ` [PATCH 0/2] printk/console: Use ttynull when no console is available or wanted Petr Mladek
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=X6wTEpJwC+ZoLSAy@kroah.com \
--to=gregkh@linuxfoundation.org \
--cc=john.ogness@linutronix.de \
--cc=linux-kernel@vger.kernel.org \
--cc=linux@roeck-us.net \
--cc=pmladek@suse.com \
--cc=rostedt@goodmis.org \
--cc=sergey.senozhatsky.work@gmail.com \
--cc=sergey.senozhatsky@gmail.com \
--cc=shreyas.joshi@biamp.com \
--cc=shreyasjoshi15@gmail.com \
--cc=torvalds@linux-foundation.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.