From owner-freebsd-hackers@FreeBSD.ORG  Fri Jun 21 21:49:27 2013
Return-Path: <owner-freebsd-hackers@FreeBSD.ORG>
Delivered-To: freebsd-hackers@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115])
 by hub.freebsd.org (Postfix) with ESMTP id DDBFAEFC
 for <freebsd-hackers@freebsd.org>; Fri, 21 Jun 2013 21:49:27 +0000 (UTC)
 (envelope-from monthadar@gmail.com)
Received: from mail-wg0-x22d.google.com (mail-wg0-x22d.google.com
 [IPv6:2a00:1450:400c:c00::22d])
 by mx1.freebsd.org (Postfix) with ESMTP id 7BF481B19
 for <freebsd-hackers@freebsd.org>; Fri, 21 Jun 2013 21:49:27 +0000 (UTC)
Received: by mail-wg0-f45.google.com with SMTP id j13so6961419wgh.12
 for <freebsd-hackers@freebsd.org>; Fri, 21 Jun 2013 14:49:26 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113;
 h=mime-version:date:message-id:subject:from:to:content-type;
 bh=gAM1kc0ZGAVCHcHb+MZ7FT/xHQFok753uXqp5u2heYQ=;
 b=hzzzYy6pe3DrlnLtyCoLoYeT43kwFgxqk6SKwtTNN7WHsV5p8Q1I68M0nArl0hzmyw
 fnvRutcRSap7+N3UFVlMTrAjuv+KOEFeHZVzLT4DxCQn5gnK7jKugrv1tiWXfb1gaMd6
 bC98LIjoyTRmuXA7LVg0yhV4Vs+lP7avBLNKYExCMi7dLSCpq5CwfxiU3dFGn6/mOGFV
 Nzl7MPPujzFvZbi6q16jwgteNtiRCvUnyV7jAfVhmrrMYA/FRaiYA+bHzUsB8D2Qu1jS
 c9K5swjQM81PYuMZ0gQKoCNO7VwsxxOhJThzHluRikU9Lad9X6x8jcT93BZOwkMHb+LW
 Fiag==
MIME-Version: 1.0
X-Received: by 10.194.243.226 with SMTP id xb2mr10736402wjc.67.1371851366604; 
 Fri, 21 Jun 2013 14:49:26 -0700 (PDT)
Received: by 10.227.196.9 with HTTP; Fri, 21 Jun 2013 14:49:26 -0700 (PDT)
Date: Fri, 21 Jun 2013 23:49:26 +0200
Message-ID: <CA+sBSoKk3EpQdmLyf7k77iM4vomD1y_71qHkPvUXJgzFTSt+SQ@mail.gmail.com>
Subject: Replace Linux skb_put with mbuf m_append
From: Monthadar Al Jaberi <monthadar@gmail.com>
To: freebsd-hackers@freebsd.org
Content-Type: text/plain; charset=ISO-8859-1
X-BeenThere: freebsd-hackers@freebsd.org
X-Mailman-Version: 2.1.14
Precedence: list
List-Id: Technical Discussions relating to FreeBSD
 <freebsd-hackers.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/options/freebsd-hackers>, 
 <mailto:freebsd-hackers-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-hackers>
List-Post: <mailto:freebsd-hackers@freebsd.org>
List-Help: <mailto:freebsd-hackers-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>,
 <mailto:freebsd-hackers-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Fri, 21 Jun 2013 21:49:27 -0000

Hi everyone,

I am porting linux skb buffers to mbufs and stumbelded on this code
from artheros 6kl driver.

struct htc_conn_service_msg *conn_msg;
...
/* assemble connect service message */
conn_msg = (struct htc_conn_service_msg *) skb_put(skb, length);
if (conn_msg == NULL) {
    goto free_packet;
}
memset(conn_msg, 0, sizeof(struct htc_conn_service_msg));
....

what skb_put does is get a pointer to the end of the buffer with
engouh space to write data there.

I have thought of chaning it to:

struct htc_conn_service_msg conn_msg;
...
memset(&conn_msg, 0, sizeof(struct htc_conn_service_msg));
....
if (m_append(m, length, (uint8_t *) &conn_msg)) {
    goto free_packet;
}

I append to the mbuf in the end.

I would like to hear your opinion on this. Is there a better faster way?

br,

--
Monthadar Al Jaberi