From owner-freebsd-hackers@FreeBSD.ORG  Wed Jun 29 09:55:48 2005
Return-Path: <owner-freebsd-hackers@FreeBSD.ORG>
X-Original-To: freebsd-hackers@freebsd.org
Delivered-To: freebsd-hackers@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id E9A3C16A41C
	for <freebsd-hackers@freebsd.org>; Wed, 29 Jun 2005 09:55:48 +0000 (GMT)
	(envelope-from sebastien.b@swissinfo.org)
Received: from md1.swissinfo.org (md1.swissinfo.org [146.159.4.92])
	by mx1.FreeBSD.org (Postfix) with ESMTP id E68DA43D4C
	for <freebsd-hackers@freebsd.org>; Wed, 29 Jun 2005 09:55:47 +0000 (GMT)
	(envelope-from sebastien.b@swissinfo.org)
Received: from mail.swissinfo.org ([194.6.181.33])
	by md1.swissinfo.org (phad1.swissinfo.org [146.159.6.9])
	(MDaemon.PRO.v7.2.1.R) with ESMTP id 08-md50000546895.msg
	for <freebsd-hackers@freebsd.org>; Wed, 29 Jun 2005 11:55:39 +0200
Received: from oasis (82.216.69.248) by mail.swissinfo.org (7.0.020)
	(authenticated as sebastien.b)
	id 4153942004444D79 for freebsd-hackers@freebsd.org;
	Wed, 29 Jun 2005 11:55:38 +0200
From: Seb <sebastien.b@swissinfo.org>
To: freebsd-hackers@freebsd.org
Date: Wed, 29 Jun 2005 11:55:50 +0200
User-Agent: KMail/1.8
References: <200506251203.13569.sebastien.b@swissinfo.org>
	<200506291051.01760.sebastien.b@swissinfo.org>
	<20050629091211.GA438@pm514-9.comsys.ntu-kpi.kiev.ua>
In-Reply-To: <20050629091211.GA438@pm514-9.comsys.ntu-kpi.kiev.ua>
MIME-Version: 1.0
Content-Type: text/plain;
  charset="iso-8859-1"
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
Message-Id: <200506291155.50929.sebastien.b@swissinfo.org>
X-Spam-Processed: phad1.swissinfo.org, Wed, 29 Jun 2005 11:55:39 +0200
	(not processed: message from valid local sender)
X-MDRemoteIP: 194.6.181.33
X-Return-Path: sebastien.b@swissinfo.org
X-MDaemon-Deliver-To: freebsd-hackers@freebsd.org
X-MDAV-Processed: phad1.swissinfo.org, Wed, 29 Jun 2005 11:55:40 +0200
Subject: Re: Accessing filesystem from a KLD
X-BeenThere: freebsd-hackers@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Technical Discussions relating to FreeBSD
	<freebsd-hackers.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/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: Wed, 29 Jun 2005 09:55:49 -0000

> Why not to use VOP_READ?  See how it is called in dev/md.c:mdstart_vnode,
> check kern/vfs_vnops.c:vn_open_cred for information how to lookup a file
> name and open it.

That's what I do, however I use the wrapper functions vn_open(), vn_rdwr() and 
so.

But I have a problem, when I call this code :

void *request_firmware(const char *name, size_t *size)
{
int flags;
char filename[40];
struct nameidata nd;
struct thread *td = curthread;
[...]
NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, &filename[0], td);
flags = FREAD;
vn_open(&nd, &flags, 0, -1);
[...]
}

from the KLD handler function (for testing) it works. But when I call it from 
a thread created by kthread_create() in another KLD, I have a page fault.
A few printfs show that the call to vn_open() is responsible for the fault.
I have not forgotten to lock Giant in my kernel thread.
Any ideas ?
Thanks,
Sebastien