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IPoIB: Call skb_dst_drop() once skb is enqueued for sending 

Currently, IPoIB delays collecting send completions for TX packets in
order to batch work more efficiently.  It does skb_orphan() right after
queuing the packets so that destructors run early, to avoid problems
like holding socket send buffers for too long (since we might not
collect a send completion until a long time after the packet is
actually sent).

However, IPoIB clears IFF_XMIT_DST_RELEASE because it actually looks
at skb_dst() to update the PMTU when it gets a too-long packet.  This
means that the packets sitting in the TX ring with uncollected send
completions are holding a reference on the dst.  We've seen this lead
to pathological behavior with respect to route and neighbour GC.  The
easy fix for this is to call skb_dst_drop() when we call skb_orphan().

Also, give packets sent via connected mode (CM) the same skb_orphan()
/ skb_dst_drop() treatment that packets sent via datagram mode get.

Signed-off-by: Roland Dreier <roland@purestorage.com>
This commit is contained in:
Roland Dreier 2012-12-19 09:16:43 -08:00
parent 5bd665f28d
commit b13912bbb4
2 changed files with 5 additions and 1 deletions
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3
drivers/infiniband/ulp/ipoib/ipoib_cm.c
View File

@ -752,6 +752,9 @@ void ipoib_cm_send(struct net_device *dev, struct sk_buff *skb, struct ipoib_cm_
dev->trans_start = jiffies;
++tx->tx_head;
skb_orphan(skb);
skb_dst_drop(skb);
if (++priv->tx_outstanding == ipoib_sendq_size) {
ipoib_dbg(priv, "TX ring 0x%x full, stopping kernel net queue\n",
tx->qp->qp_num);

3
drivers/infiniband/ulp/ipoib/ipoib_ib.c
View File

@ -615,8 +615,9 @@ void ipoib_send(struct net_device *dev, struct sk_buff *skb,
address->last_send = priv->tx_head;
++priv->tx_head;
skb_orphan(skb);
skb_orphan(skb);
skb_dst_drop(skb);
}
if (unlikely(priv->tx_outstanding > MAX_SEND_CQE))