From: Petr Mladek <pmladek@suse.com>
To: 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,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [PATCH printk v2 4/5] printk: Add per-console suspended state
Date: Thu, 13 Jul 2023 17:53:09 +0200 [thread overview]
Message-ID: <ZLAd5cRNmOv-_1vW@alley> (raw)
In-Reply-To: <20230710134524.25232-5-john.ogness@linutronix.de>
On Mon 2023-07-10 15:51:23, John Ogness wrote:
> Currently the global @console_suspended is used to determine if
> consoles are in a suspended state. Its primary purpose is to allow
> usage of the console_lock when suspended without causing console
> printing. It is synchronized by the console_lock.
>
> Rather than relying on the console_lock to determine suspended
> state, make it an official per-console state that is set within
> console->flags. This allows the state to be queried via SRCU.
>
> Remove @console_suspended. Console printing will still be avoided
> when suspended because console_is_usable() returns false when
> the new suspended flag is set for that console.
>
> Signed-off-by: John Ogness <john.ogness@linutronix.de>
Looks good to me:
Reviewed-by: Petr Mladek <pmladek@suse.com>
I have double checked the history. suspend_console() was added
into v2.6.18-rc1 by the commit ("Add support for suspending and
resuming the whole console subsystem").
The above commit added "secondary_console_sem". It was taken
by acquire_console_sem() instead of the normal "console_sem"
when "console_suspended" was set. It means that the normal
"console_sem" really was not taken.
The "secondary_console_sem" was removed in v2.6.29-rc6 by the commit
("PM: Fix suspend_console and resume_console to use only one
semaphore"). It solved races between code taking "console_sem"
and code "secondary_console_sem". This commit kept the handling of
"console_locked". It was not set when console_suspended was set
even though "console_sem" was actually taken.
IMHO, it was a bug in the commit removing "secondary_console_sem".
But it probably never caused any issues.
Anyway, this patch makes "console_locked" handling sane. And if some
tty code relies on the insane logic then it should get fixed.
Best Regards,
Petr
next prev parent reply other threads:[~2023-07-13 15:53 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-10 13:45 [PATCH printk v2 0/5] various cleanups John Ogness
2023-07-10 13:45 ` [PATCH printk v2 1/5] kdb: do not assume write() callback available John Ogness
2023-07-11 0:25 ` Sergey Senozhatsky
2023-07-11 8:23 ` Daniel Thompson
2023-07-11 8:58 ` John Ogness
2023-07-11 9:01 ` Daniel Thompson
2023-07-10 13:45 ` [PATCH printk v2 2/5] printk: Add NMI safety to console_flush_on_panic() and console_unblank() John Ogness
2023-07-11 15:43 ` Petr Mladek
2023-07-11 16:07 ` Sergey Senozhatsky
2023-07-12 21:11 ` John Ogness
2023-07-13 14:43 ` Petr Mladek
2023-07-14 4:00 ` Sergey Senozhatsky
2023-07-14 9:41 ` Petr Mladek
2023-07-10 13:45 ` [PATCH printk v2 3/5] printk: Consolidate console deferred printing John Ogness
2023-07-11 15:17 ` Sergey Senozhatsky
2023-07-13 14:51 ` Petr Mladek
2023-07-10 13:45 ` [PATCH printk v2 4/5] printk: Add per-console suspended state John Ogness
2023-07-11 15:08 ` Sergey Senozhatsky
2023-07-11 15:23 ` John Ogness
2023-07-11 15:26 ` Sergey Senozhatsky
2023-07-11 15:30 ` Sergey Senozhatsky
2023-07-13 15:53 ` Petr Mladek [this message]
2023-07-10 13:45 ` [PATCH printk v2 5/5] printk: Rename abandon_console_lock_in_panic() to other_cpu_in_panic() John Ogness
2023-07-11 0:22 ` Sergey Senozhatsky
2023-07-13 15:55 ` 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=ZLAd5cRNmOv-_1vW@alley \
--to=pmladek@suse.com \
--cc=gregkh@linuxfoundation.org \
--cc=john.ogness@linutronix.de \
--cc=linux-kernel@vger.kernel.org \
--cc=rostedt@goodmis.org \
--cc=senozhatsky@chromium.org \
--cc=tglx@linutronix.de \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox