IPoIB/CM: Enable SRQ support on HCAs that support fewer than 16 SG entries

Some HCAs (such as ehca2) support SRQ, but only support fewer than 16 SG
entries for SRQs.  Currently IPoIB/CM implicitly assumes all HCAs will
support 16 SG entries for SRQs (to handle a 64K MTU with 4K pages). This
patch removes that restriction by limiting the maximum MTU in connected
mode to what the maximum number of SRQ SG entries allows.

This patch addresses <https://bugs.openfabrics.org/show_bug.cgi?id=728>

Signed-off-by: Pradeep Satyanarayana <pradeeps@linux.vnet.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

1 files changed, 13 insertions, 0 deletions

diff --git a/drivers/infiniband/ulp/ipoib/ipoib.h b/drivers/infiniband/ulp/ipoib/ipoib.h
index d35025f0652b..fe250c60607d 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib.h
+++ b/drivers/infiniband/ulp/ipoib/ipoib.h
@@ -238,6 +238,8 @@ struct ipoib_cm_dev_priv {
         struct ib_sge           rx_sge[IPOIB_CM_RX_SG];
         struct ib_recv_wr       rx_wr;
         int                     nonsrq_conn_qp;
+        int                     max_cm_mtu;
+        int                     num_frags;
 };
 
 /*
@@ -503,6 +505,12 @@ static inline int ipoib_cm_has_srq(struct net_device *dev)
         return !!priv->cm.srq;
 }
 
+static inline unsigned int ipoib_cm_max_mtu(struct net_device *dev)
+{
+        struct ipoib_dev_priv *priv = netdev_priv(dev);
+        return priv->cm.max_cm_mtu;
+}
+
 void ipoib_cm_send(struct net_device *dev, struct sk_buff *skb, struct ipoib_cm_tx *tx);
 int ipoib_cm_dev_open(struct net_device *dev);
 void ipoib_cm_dev_stop(struct net_device *dev);
@@ -552,6 +560,11 @@ static inline int ipoib_cm_has_srq(struct net_device *dev)
         return 0;
 }
 
+static inline unsigned int ipoib_cm_max_mtu(struct net_device *dev)
+{
+        return 0;
+}
+
 static inline
 void ipoib_cm_send(struct net_device *dev, struct sk_buff *skb, struct ipoib_cm_tx *tx)
 {