[openib-general] [PATCH] IB/ipoib: user appropriate mtu selector for path queries

[Michael S. Tsirkin]

Roland, the patch is still under test (I'll leave it to run
for a nigh), but I'd like to get comments on the following:


IB/ipoib: user appropriate mtu selector for path queries

IPoIB must set mtu selector in path record query according to dev->mtu:
if we wildcard it, SM can select a path with lower MTU.
This breaks IPoIB on networks with SM Tavor quirk activates.

We can always require this, since IPoIB spec includes the following statement:
    The value (for IB MTU) assigned to the broadcast-GID must not
    be greater than any physical link MTU spanned by the IPoIB
    subnet.

Signed-off-by: Michael S. Tsirkin <mst at mellanox.co.il>

---

Note the following uses IB_SA_GT so it should be applied on top of SA
enum rename.

Index: ofed_1_1/drivers/infiniband/ulp/ipoib/ipoib_main.c
===================================================================
--- ofed_1_1.orig/drivers/infiniband/ulp/ipoib/ipoib_main.c
+++ ofed_1_1/drivers/infiniband/ulp/ipoib/ipoib_main.c
@@ -182,6 +182,8 @@ static int ipoib_change_mtu(struct net_d
 
 	dev->mtu = min(priv->mcast_mtu, priv->admin_mtu);
 
+	queue_work(ipoib_workqueue, &priv->flush_task);
+
 	return 0;
 }
 
@@ -452,15 +454,39 @@ static int path_rec_start(struct net_dev
 			  struct ipoib_path *path)
 {
 	struct ipoib_dev_priv *priv = netdev_priv(dev);
+	ib_sa_comp_mask comp_mask = IB_SA_PATH_REC_MTU_SELECTOR | IB_SA_PATH_REC_MTU;
+
+	path->pathrec.mtu_selector = IB_SA_GT;
 
-	ipoib_dbg(priv, "Start path record lookup for " IPOIB_GID_FMT "\n",
-		  IPOIB_GID_ARG(path->pathrec.dgid));
+	switch (roundup_pow_of_two(dev->mtu + IPOIB_ENCAP_LEN)) {
+	case 512:
+		path->pathrec.mtu = IB_MTU_256;
+		break;
+	case 1024:
+		path->pathrec.mtu = IB_MTU_512;
+		break;
+	case 2048:
+		path->pathrec.mtu = IB_MTU_1024;
+		break;
+	case 4096:
+		path->pathrec.mtu = IB_MTU_2048;
+		break;
+	default:
+		/* Wildcard everything */
+		comp_mask = 0;
+		path->pathrec.mtu = 0;
+		path->pathrec.mtu_selector = 0;
+	}
+
+	ipoib_dbg(priv, "Start path record lookup for " IPOIB_GID_FMT " MTU > %d\n",
+		  IPOIB_GID_ARG(path->pathrec.dgid),
+		  comp_mask ? ib_mtu_enum_to_int(path->pathrec.mtu) : 0);
 
 	init_completion(&path->done);
 
 	path->query_id =
 		ib_sa_path_rec_get(priv->ca, priv->port,
-				   &path->pathrec,
+				   &path->pathrec, comp_mask    |
 				   IB_SA_PATH_REC_DGID		|
 				   IB_SA_PATH_REC_SGID		|
 				   IB_SA_PATH_REC_NUMB_PATH	|

-- 
MST