netdev - Re: tun: Use netif_receive_skb instead of netif

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

Message-ID: <20100519125543.GA26519@hmsreliant.think-freely.org>
Date:	Wed, 19 May 2010 08:55:43 -0400
From:	Neil Horman <nhorman@...driver.com>
To:	Neil Horman <nhorman@...hat.com>
Cc:	Eric Dumazet <eric.dumazet@...il.com>,
	Herbert Xu <herbert@...dor.hengli.com.au>,
	"David S. Miller" <davem@...emloft.net>,
	Thomas Graf <tgraf@...hat.com>, netdev@...r.kernel.org
Subject: Re: tun: Use netif_receive_skb instead of netif_rx

On Wed, May 19, 2010 at 08:05:47AM -0400, Neil Horman wrote:
> On Wed, May 19, 2010 at 10:18:09AM +0200, Eric Dumazet wrote:
> > Le mercredi 19 mai 2010 à 10:09 +0200, Eric Dumazet a écrit :
> > 
> > > Another concern I have is about RPS.
> > > 
> > > netif_receive_skb() must be called from process_backlog() context, or
> > > there is no guarantee the IPI will be sent if this skb is enqueued for
> > > another cpu.
> > 
> > Hmm, I just checked again, and this is wrong.
> > 
> > In case we enqueue skb on a remote cpu backlog, we also
> > do __raise_softirq_irqoff(NET_RX_SOFTIRQ); so the IPI will be done
> > later.
> > 
> But if this happens, then we loose the connection between the packet being
> received and the process doing the reception, so the network cgroup classifier
> breaks again.
> 
> Performance gains are still a big advantage here of course.
> Neil
> 
Scratch what I said here, Herbert corrected me on this, and we're ok, as tun has
no rps map.

I'll test this patch out in just a bit
Neil

> --
> 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
> 
--
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