lkml.org 
[lkml]   [2010]   [Apr]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [Bonding-devel] [v3 Patch 2/3] bridge: make bridge support netpoll
    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.

    --
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2010-04-13 10:57    [W:0.027 / U:30.580 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site