From: Joe Perches <joe@perches.com>
To: Kay Sievers <kay@vrfy.org>
Cc: linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Len Brown <lenb@kernel.org>
Subject: Re: [PATCH] printk(): add KERN_CONT where needed
Date: Tue, 03 Apr 2012 07:32:52 -0700 [thread overview]
Message-ID: <1333463572.26079.31.camel@joe2Laptop> (raw)
In-Reply-To: <CAPXgP13fDRZtAvV651NPqQ2TgUEtb+MX1EhKhwirAgoiNOg5tQ@mail.gmail.com>
On Tue, 2012-04-03 at 12:30 +0200, Kay Sievers wrote:
> On Tue, Apr 3, 2012 at 05:47, Joe Perches <joe@perches.com> wrote:
> > I think you should do it "right" rather than add
> > trivial markers.
>
> The trivial markers _are_ correct. And they really fix things as soon
> as we start storing machine-readable records with printk(), instead of
> blindly glueing bytes together with each printk() call, for humans to
> puzzle with them if things go wrong.
These KERN_CONT changes don't _fix_ things,
they just make it less likely to cause problems.
Imagine two threads with printks extended with
KERN_CONT
Thread 1: Thread 2:
printk(KERN_INFO "info message: ");
printk(KERN_ERR "err message: ");
printk(KERN_CONT "online\n");
printk(KERN_CONT "offline\n");
Instead of a guarantee of "info message: online" and
"err message: offline", buffering could still join
the messages to "err message: online".
I believe the only _guaranteed_ way to correctly
assemble these messages is to use a initiator with
a cookie and pass that cookie to assembling printks.
Something like:
cookie = multi_printk_start()
multi_printk(cookie, level fmt, ...);
...
multi_printk_end(cookie);
Though get_current() might be a reasonable cookie
so perhaps the multi_ variants aren't needed.
git.kernel.org isn't responding right now. I
can't read the link you sent me privately to
check if you are using get_current() or some
other current_thread_info() constuct.
next prev parent reply other threads:[~2012-04-03 14:32 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-03 1:18 [PATCH] printk(): add KERN_CONT where needed Kay Sievers
2012-04-03 2:36 ` Joe Perches
2012-04-03 3:00 ` Kay Sievers
2012-04-03 3:03 ` Joe Perches
2012-04-03 3:47 ` Joe Perches
2012-04-03 10:30 ` Kay Sievers
2012-04-03 14:32 ` Joe Perches [this message]
2012-04-03 15:50 ` Kay Sievers
2012-04-03 16:05 ` Joe Perches
2012-04-03 16:11 ` Kay Sievers
2012-04-03 16:16 ` Joe Perches
2012-04-03 16:20 ` Kay Sievers
2012-04-03 16:27 ` Joe Perches
2012-04-09 23:08 ` Andrew Morton
2012-04-09 23:37 ` Joe Perches
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=1333463572.26079.31.camel@joe2Laptop \
--to=joe@perches.com \
--cc=akpm@linux-foundation.org \
--cc=gregkh@linuxfoundation.org \
--cc=kay@vrfy.org \
--cc=lenb@kernel.org \
--cc=linux-kernel@vger.kernel.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).