From: Petr Mladek <pmladek@suse.com>
To: "Thomas Weißschuh" <linux@weissschuh.net>
Cc: Joe Perches <joe@perches.com>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Pavel Machek <pavel@ucw.cz>, Len Brown <len.brown@intel.com>,
linux-pm@vger.kernel.org,
Sergey Senozhatsky <senozhatsky@chromium.org>,
Andy Whitcroft <apw@canonical.com>,
linux-kernel@vger.kernel.org,
Steven Rostedt <rostedt@goodmis.org>,
Dwaipayan Ray <dwaipayanray1@gmail.com>,
Lukas Bulwahn <lukas.bulwahn@gmail.com>
Subject: Re: [PATCH v2 3/3] power: process: use explicit levels for printk continuations
Date: Wed, 30 Nov 2022 16:06:19 +0100 [thread overview]
Message-ID: <Y4dxa3YMsfhOZpPZ@alley> (raw)
In-Reply-To: <ad4e4785-c6f8-4ae1-a281-ff9dc5720db2@t-8ch.de>
On Fri 2022-11-25 21:41:55, Thomas Weißschuh wrote:
> On 2022-11-25 11:53-0800, Joe Perches wrote:
> > On Fri, 2022-11-25 at 20:09 +0100, Thomas Weißschuh wrote:
> >> Many of the printk messages emitted during suspend and resume are
> >> emitted in fragments using pr_cont()/KERN_CONT.
> >>
> >> As during suspend and resume a lot of operations are happing in the
> >> kernel the chances are high that the fragments are interspersed with
> >> unrelated messages.
> >>
> >> In this case if no explicit level is specified for the fragments the
> >> standard level is applied, which by default is KERN_WARNING.
> >>
> >> If the user is only observing KERN_WARNING and *not* KERN_INFO messages
> >> they will see incomplete message fragments.
> >>
> >> By specifing the correct printk level also with the continuations this
> >> mismatch can be avoided.
> >> Also it reduces the amount of false-positive KERN_WARNING messages.
> >>
> >> Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
> >> ---
> >> kernel/power/process.c | 18 +++++++++---------
> >> 1 file changed, 9 insertions(+), 9 deletions(-)
> >>
> >> diff --git a/kernel/power/process.c b/kernel/power/process.c
> > []
> >> @@ -82,7 +82,7 @@ static int try_to_freeze_tasks(bool user_only)
> >> elapsed_msecs = ktime_to_ms(elapsed);
> >>
> >> if (todo) {
> >> - pr_cont("\n");
> >> + pr_info_cont("\n");
> >
> > I think this isn't needed because of the immediately following pr_err.
Great catch.
> The pr_cont() itself or the conversion to pr_info_cont() is not needed?
The pr_cont() was needed before the commit 4bcc595ccd80decb42450
("printk: reinstate KERN_CONT for printing continuation lines").
Before this commit, lines were appended even without KERN_CONT
when the previous line did not end with "\n".
The above commit caused that only lines with KERN_CONT will be
appended.
We have the code:
pr_cont("\n");
pr_err("Freezing of tasks %s after %d.%03d seconds "
The pr_cont() is not needed here because pr_err() does not have
KERN_CONT. It will always start on a new line.
> Personally I would prefer to keep the patch as is.
>
> If only the conversion is not needed for consistency with the rest of the file.
> If the pr_cont() in general is not needed it should be changed in a dedicated
> patch (by somebody who knows this code better).
I agree that it should be removed in a separate patch. The commit
message should mention the commit that modified the KERN_CONT
handling.
Best Regards,
Petr
next prev parent reply other threads:[~2022-11-30 15:06 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-25 19:09 [PATCH v2 0/3] printk: introduce new macros pr_<level>_cont() Thomas Weißschuh
2022-11-25 19:09 ` [PATCH v2 1/3] " Thomas Weißschuh
2022-11-25 20:18 ` Joe Perches
2022-11-25 20:33 ` Thomas Weißschuh
2022-11-30 13:59 ` Petr Mladek
2022-11-30 14:50 ` Thomas Weißschuh
2022-12-02 12:21 ` Petr Mladek
2022-11-30 14:23 ` Petr Mladek
2022-11-30 14:56 ` Thomas Weißschuh
2022-12-02 12:27 ` Petr Mladek
2022-11-25 19:09 ` [PATCH v2 2/3] checkpatch: handle new pr_<level>_cont macros Thomas Weißschuh
2022-11-25 20:17 ` Joe Perches
2022-11-30 14:51 ` Petr Mladek
2022-11-25 19:09 ` [PATCH v2 3/3] power: process: use explicit levels for printk continuations Thomas Weißschuh
2022-11-25 19:53 ` Joe Perches
2022-11-25 20:41 ` Thomas Weißschuh
2022-11-30 15:06 ` Petr Mladek [this message]
2022-11-30 17:57 ` [PATCH v2 0/3] printk: introduce new macros pr_<level>_cont() Rafael J. Wysocki
2022-11-30 23:37 ` Thomas Weißschuh
2022-12-01 10:32 ` 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=Y4dxa3YMsfhOZpPZ@alley \
--to=pmladek@suse.com \
--cc=apw@canonical.com \
--cc=dwaipayanray1@gmail.com \
--cc=joe@perches.com \
--cc=len.brown@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pm@vger.kernel.org \
--cc=linux@weissschuh.net \
--cc=lukas.bulwahn@gmail.com \
--cc=pavel@ucw.cz \
--cc=rafael@kernel.org \
--cc=rostedt@goodmis.org \
--cc=senozhatsky@chromium.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).