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Date: Wed, 16 May 2007 17:06:46 +0530
From: "Satyam Sharma" <satyam.sharma@gmail.com>
To: "Jiri Kosina" <jikos@jikos.cz>
Subject: Re: 2.6.21-rc7: BUG: sleeping function called from invalid context at net/core/sock.c:1523
Cc: "Marcel Holtmann" <marcel@holtmann.org>, "Greg KH" <gregkh@suse.de>,
        "Jeremy Fitzhardinge" <jeremy@goop.org>, maxk@qualcomm.com,
        bluez-devel@lists.sourceforge.net, "Cedric Le Goater" <clg@fr.ibm.com>,
        "Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
        netdev@vger.kernel.org
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Hi Jiri,

On 5/16/07, Jiri Kosina <jikos@jikos.cz> wrote:
> On Fri, 11 May 2007, Satyam Sharma wrote:
> > (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.

Thanks,
Satyam