Commit b13912bb authored Dec 19, 2012 by Roland Dreier

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>

parent 5bd665f2

drivers/infiniband/ulp/ipoib/ipoib_cm.c

+3 −0

Original line number	Original line	Diff line number	Diff line
	@@ -752,6 +752,9 @@ void ipoib_cm_send(struct net_device dev, struct sk_buff skb, struct ipoib_cm_
	dev->trans_start = jiffies;		dev->trans_start = jiffies;
	++tx->tx_head;		++tx->tx_head;

			skb_orphan(skb);
			skb_dst_drop(skb);

	if (++priv->tx_outstanding == ipoib_sendq_size) {		if (++priv->tx_outstanding == ipoib_sendq_size) {
	ipoib_dbg(priv, "TX ring 0x%x full, stopping kernel net queue\n",		ipoib_dbg(priv, "TX ring 0x%x full, stopping kernel net queue\n",
	tx->qp->qp_num);		tx->qp->qp_num);

drivers/infiniband/ulp/ipoib/ipoib_ib.c

+2 −1

Original line number	Original line	Diff line number	Diff line
	@@ -615,8 +615,9 @@ void ipoib_send(struct net_device dev, struct sk_buff skb,

	address->last_send = priv->tx_head;		address->last_send = priv->tx_head;
	++priv->tx_head;		++priv->tx_head;
	skb_orphan(skb);

			skb_orphan(skb);
			skb_dst_drop(skb);
	}		}

	if (unlikely(priv->tx_outstanding > MAX_SEND_CQE))		if (unlikely(priv->tx_outstanding > MAX_SEND_CQE))