IB/ipoib: Fix transmit queue stalling forever

Commit f56bcd80 ("IPoIB: Use separate CQ for UD send completions")
introduced a bug where the transmit queue could get stopped and never
woken up.  The problem is that send completions are only polled at the
end of the xmit function, so if the send queue fills up and the xmit
path stops the queue, then there is no way for send completions to
ever get polled, and so the transmit queue stays stopped forever.

Fix this by arming the send CQ just before posting the last send
request that fills the send queue.  Then, when the completion event
handler is called, drain the send CQ.  Since it is possible that not
enough send completions are in the CQ, verify that the the net queue
has been woken up after draining the send CQ, and if not arm a timer
and drain again at the timer function.

Signed-off-by: Roland Dreier <rolandd@cisco.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/infiniband/ulp/ipoib/ipoib.h b/drivers/infiniband/ulp/ipoib/ipoib.h
index 9044f8803532..ca126fc2b853 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib.h
+++ b/drivers/infiniband/ulp/ipoib/ipoib.h
@@ -334,6 +334,7 @@ struct ipoib_dev_priv {
 #endif
         int     hca_caps;
         struct ipoib_ethtool_st ethtool;
+        struct timer_list poll_timer;
 };
 
 struct ipoib_ah {
@@ -404,6 +405,7 @@ extern struct workqueue_struct *ipoib_workqueue;
 
 int ipoib_poll(struct napi_struct *napi, int budget);
 void ipoib_ib_completion(struct ib_cq *cq, void *dev_ptr);
+void ipoib_send_comp_handler(struct ib_cq *cq, void *dev_ptr);
 
 struct ipoib_ah *ipoib_create_ah(struct net_device *dev,
                                  struct ib_pd *pd, struct ib_ah_attr *attr);