From: Johannes Berg <johannes@sipsolutions.net>
To: Li Zefan <lizf@cn.fujitsu.com>
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@elte.hu>,
Frederic Weisbecker <fweisbec@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>
Subject: Re: event tracing, ringbuffer and RB_MAX_SMALL_DATA
Date: Wed, 15 Jul 2009 11:48:25 +0200 [thread overview]
Message-ID: <1247651305.14973.3.camel@johannes.local> (raw)
In-Reply-To: <4A5D2BF6.6010802@cn.fujitsu.com>
[-- Attachment #1: Type: text/plain, Size: 769 bytes --]
On Wed, 2009-07-15 at 09:08 +0800, Li Zefan wrote:
> Right, the length of a dynamic array is not recorded, and this
> causes 2 problems:
>
> - the event filter is not working properly for dynamic strings
> - userspace parsers can't figure out the length of those arrays
>
> I had an idea some time ago, and hopefully will send out a
> patch today or tomorrow.
Well except for the corner case I pointed out, you can determine the
length of dynamic arrays by either
- the next dynamic array's offset or
- the length of the item.
So, afaict, the simplest solution would be to not embed the length of
the item in type_len if it's not divisible by four and contains dynamic
members, though the latter condition might be hard to check.
johannes
[-- Attachment #2: This is a digitally signed message part --]
[-- Type: application/pgp-signature, Size: 801 bytes --]
next prev parent reply other threads:[~2009-07-15 9:49 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-07-14 17:18 Johannes Berg
2009-07-15 1:08 ` Li Zefan
2009-07-15 9:48 ` Johannes Berg [this message]
2009-07-16 0:48 ` Li Zefan
2009-07-21 1:25 ` Steven Rostedt
2009-07-21 1:30 ` Li Zefan
2009-07-21 1:42 ` Steven Rostedt
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=1247651305.14973.3.camel@johannes.local \
--to=johannes@sipsolutions.net \
--cc=fweisbec@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=lizf@cn.fujitsu.com \
--cc=mingo@elte.hu \
--cc=rostedt@goodmis.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
all inboxes | Powered by JetHome®