From: Marcel Holtmann <marcel@holtmann.org>
To: Satyam Sharma <satyam.sharma@gmail.com>
In-Reply-To: <a781481a0705160436s3564022aybd9b318ec0947d94@mail.gmail.com>
References: <462D1B09.9050005@goop.org>
	<Pine.LNX.4.64.0704232257090.20657@twin.jikos.cz>
	<Pine.LNX.4.64.0704261625410.20657@twin.jikos.cz>
	<a781481a0705110629n7c7130c1x3a89fa958b271f20@mail.gmail.com>
	<Pine.LNX.4.64.0705161124030.25986@twin.jikos.cz>
	<a781481a0705160436s3564022aybd9b318ec0947d94@mail.gmail.com>
Date: Wed, 16 May 2007 13:45:04 +0200
Message-Id: <1179315904.10069.67.camel@violet>
Mime-Version: 1.0
Cc: Jeremy Fitzhardinge <jeremy@goop.org>, netdev@vger.kernel.org,
        Greg KH <gregkh@suse.de>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Jiri Kosina <jikos@jikos.cz>, Cedric Le Goater <clg@fr.ibm.com>,
        bluez-devel@lists.sourceforge.net, maxk@qualcomm.com
Subject: Re: [Bluez-devel] 2.6.21-rc7: BUG: sleeping function called from
	invalid context	at net/core/sock.c:1523
Reply-To: BlueZ development <bluez-devel@lists.sourceforge.net>
Content-Type: text/plain; charset="us-ascii"
Sender: bluez-devel-bounces@lists.sourceforge.net
Errors-To: bluez-devel-bounces@lists.sourceforge.net

Hi Satayam,

> > > (later)
> > > I Googled a bit to see if this problem was faced elsewhere in the kernel
> > > too. Saw the following commit by Ingo Molnar
> > > (9883a13c72dbf8c518814b6091019643cdb34429):
> > > -     lock_sock(sock->sk);
> > > +     local_bh_disable();
> > > +     bh_lock_sock_nested(sock->sk);
> > >       rc = selinux_netlbl_socket_setsid(sock, sksec->sid);
> > > -     release_sock(sock->sk);
> > > +     bh_unlock_sock(sock->sk);
> > > +     local_bh_enable();
> > > Is it _really_ *this* simple?
> > [...]
> > actually this *seems* to be proper solution also for our case, thanks for
> > pointing this out. I will think about it once again, do some more tests
> > with this locking scheme, and will let you know.
> 
> Yes, I can almost confirm that this (open-coding of spin_lock_bh,
> effectively) is the proper solution (Rusty's unreliable guide to
> kernel-locking needs to be next to every developer's keyboard :-)
> I also came across this idiom in other places in the networking code
> so it seems to be pretty much the standard way. I wish I owned
> bluetooth hardware, could've tested this for you myself.

does this mean we should revert previous changes to the locking or only
apply this on top of it?

Regards

Marcel


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