IB/mthca: Fix dispatch of IB_EVENT_LID_CHANGE event

When snooping a PortInfo MAD, its client_reregister bit is checked.
If the bit is ON then a CLIENT_REREGISTER event is dispatched,
otherwise a LID_CHANGE event is dispatched.  This way of decision
ignores the cases where the MAD changes the LID along with an
instruction to reregister (so a necessary LID_CHANGE event won't be
dispatched) or the MAD is neither of these (and an unnecessary
LID_CHANGE event will be dispatched).

This causes problems at least with IPoIB, which will do a "light"
flush on reregister, rather than the "heavy" flush required due to a
LID change.

Fix this by dispatching a CLIENT_REREGISTER event if the
client_reregister bit is set, but also compare the LID in the MAD to
the current LID.  If and only if they are not identical then a
LID_CHANGE event is dispatched.

Signed-off-by: Moni Shoua <monis@voltaire.com>
Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Yossi Etigin <yosefe@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

1 files changed, 19 insertions, 6 deletions

diff --git a/drivers/infiniband/hw/mthca/mthca_mad.c b/drivers/infiniband/hw/mthca/mthca_mad.c
index 640449582aba..5648659ff0b0 100644
--- a/drivers/infiniband/hw/mthca/mthca_mad.c
+++ b/drivers/infiniband/hw/mthca/mthca_mad.c
@@ -104,7 +104,8 @@ static void update_sm_ah(struct mthca_dev *dev,
  */
 static void smp_snoop(struct ib_device *ibdev,
                       u8 port_num,
-                      struct ib_mad *mad)
+                      struct ib_mad *mad,
+                      u16 prev_lid)
 {
         struct ib_event event;
 
@@ -114,6 +115,7 @@ static void smp_snoop(struct ib_device *ibdev,
                 if (mad->mad_hdr.attr_id == IB_SMP_ATTR_PORT_INFO) {
                         struct ib_port_info *pinfo =
                                 (struct ib_port_info *) ((struct ib_smp *) mad)->data;
+                        u16 lid = be16_to_cpu(pinfo->lid);
 
                         mthca_update_rate(to_mdev(ibdev), port_num);
                         update_sm_ah(to_mdev(ibdev), port_num,
@@ -123,12 +125,15 @@ static void smp_snoop(struct ib_device *ibdev,
                         event.device           = ibdev;
                         event.element.port_num = port_num;
 
-                        if (pinfo->clientrereg_resv_subnetto & 0x80)
+                        if (pinfo->clientrereg_resv_subnetto & 0x80) {
                                 event.event    = IB_EVENT_CLIENT_REREGISTER;
-                        else
-                                event.event    = IB_EVENT_LID_CHANGE;
+                                ib_dispatch_event(&event);
+                        }
 
-                        ib_dispatch_event(&event);
+                        if (prev_lid != lid) {
+                                event.event    = IB_EVENT_LID_CHANGE;
+                                ib_dispatch_event(&event);
+                        }
                 }
 
                 if (mad->mad_hdr.attr_id == IB_SMP_ATTR_PKEY_TABLE) {
@@ -196,6 +201,8 @@ int mthca_process_mad(struct ib_device *ibdev,
         int err;
         u8 status;
         u16 slid = in_wc ? in_wc->slid : be16_to_cpu(IB_LID_PERMISSIVE);
+        u16 prev_lid = 0;
+        struct ib_port_attr pattr;
 
         /* Forward locally generated traps to the SM */
         if (in_mad->mad_hdr.method == IB_MGMT_METHOD_TRAP &&
@@ -233,6 +240,12 @@ int mthca_process_mad(struct ib_device *ibdev,
                         return IB_MAD_RESULT_SUCCESS;
         } else
                 return IB_MAD_RESULT_SUCCESS;
+        if ((in_mad->mad_hdr.mgmt_class == IB_MGMT_CLASS_SUBN_LID_ROUTED ||
+             in_mad->mad_hdr.mgmt_class == IB_MGMT_CLASS_SUBN_DIRECTED_ROUTE) &&
+            in_mad->mad_hdr.method == IB_MGMT_METHOD_SET &&
+            in_mad->mad_hdr.attr_id == IB_SMP_ATTR_PORT_INFO &&
+            !ib_query_port(ibdev, port_num, &pattr))
+                prev_lid = pattr.lid;
 
         err = mthca_MAD_IFC(to_mdev(ibdev),
                             mad_flags & IB_MAD_IGNORE_MKEY,
@@ -252,7 +265,7 @@ int mthca_process_mad(struct ib_device *ibdev,
         }
 
         if (!out_mad->mad_hdr.status) {
-                smp_snoop(ibdev, port_num, in_mad);
+                smp_snoop(ibdev, port_num, in_mad, prev_lid);
                 node_desc_override(ibdev, out_mad);
         }