Messages in this thread |  | | | Date | Tue, 13 Apr 2010 16:57:56 +0800 | | From | Cong Wang <> | | Subject | Re: [Bonding-devel] [v3 Patch 2/3] bridge: make bridge support netpoll |
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Stephen Hemminger wrote: > On Mon, 12 Apr 2010 12:38:57 +0200 > Eric Dumazet <eric.dumazet@gmail.com> wrote: > >> Le lundi 12 avril 2010 à 18:37 +0800, Cong Wang a écrit : >>> Stephen Hemminger wrote: >>>> There is no protection on dev->priv_flags for SMP access. >>>> It would better bit value in dev->state if you are using it as control flag. >>>> >>>> Then you could use >>>> if (unlikely(test_and_clear_bit(__IN_NETPOLL, &skb->dev->state))) >>>> netpoll_send_skb(...) >>>> >>>> >>> Hmm, I think we can't use ->state here, it is not for this kind of purpose, >>> according to its comments. >>> >>> Also, I find other usages of IFF_XXX flags of ->priv_flags are also using >>> &, | to set or clear the flags. So there must be some other things preventing >>> the race... >> Yes, its RTNL that protects priv_flags changes, hopefully... >> > > The patch was not protecting priv_flags with RTNL. > For example.. > > > @@ -308,7 +312,9 @@ static void netpoll_send_skb(struct netp > tries > 0; --tries) { > if (__netif_tx_trylock(txq)) { > if (!netif_tx_queue_stopped(txq)) { > + dev->priv_flags |= IFF_IN_NETPOLL; > status = ops->ndo_start_xmit(skb, dev); > + dev->priv_flags &= ~IFF_IN_NETPOLL; > if (status == NETDEV_TX_OK) > txq_trans_update(txq);
Hmm, but I checked the bonding case (IFF_BONDING), it doesn't hold rtnl_lock. Strange.
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