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>
diff --git a/drivers/infiniband/ulp/ipoib/ipoib_cm.c b/drivers/infiniband/ulp/ipoib/ipoib_cm.c
index 72ae63f..03103d2 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_cm.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_cm.c
@@ -752,6 +752,9 @@
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);
diff --git a/drivers/infiniband/ulp/ipoib/ipoib_ib.c b/drivers/infiniband/ulp/ipoib/ipoib_ib.c
index f10221f..a1bca70 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_ib.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_ib.c
@@ -615,8 +615,9 @@
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))