netdev - Re: [PATCH 1/2] mac802154: add a software MAC 802.15.4 implementation

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:	Thu, 13 Aug 2009 00:46:04 +0400
From:	Dmitry Eremin-Solenikov <dbaryshkov@...il.com>
To:	Johannes Berg <johannes@...solutions.net>
Cc:	netdev@...r.kernel.org, linux-wireless@...r.kernel.org,
	Sergey Lapin <slapin@...fans.org>
Subject: Re: [PATCH 1/2] mac802154: add a software MAC 802.15.4
 implementation

On Wed, Aug 12, 2009 at 03:13:57PM +0200, Johannes Berg wrote:
> On Wed, 2009-08-12 at 17:06 +0400, Dmitry Eremin-Solenikov wrote:
> 
> > > In addition to that, you can't put anything into skb->cb, then push the
> > > frame to the master netdev, and expect things in skb->cb to still be
> > > there when the frame arrives at the master netdev. Not sure you do that
> > > (I hope not because that would be very buggy), but eventually you'll
> > > probably find that you do want that, etc.
> > 
> > Hmm. It works for us. Could you please tell me more about the problems
> > with skb->cb ?
> 
> Uh, well, you don't own the skb->cb between dev_queue_xmit() and
> ndo_start_xmit(). In fact, your phy_cb data will be overwritten by the
> qdisc.

Hmmm. Really weird. Then, if we want to pass data from socket layer to
MAC layer, we should place data in skb->data and not in skb->cb (like
radiotap header)?

> Also, looking into this a bit more, I see no reason to allocate a work
> struct every time you get a frame -- better just queue them up and stick
> everything else into skb->cb. In fact, you don't need a master netdev
> here anyway, just move all code from ieee802154_master_hard_start_xmit()
> into ieee802154_net_xmit().
> 

Nice idea. Thanks a lot!

-- 
With best wishes
Dmitry

--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html