LU-12424 lnet: prevent loop in LNetPrimaryNID()

[fs/lustre-release.git] / lnet / lnet / peer.c

diff --git a/lnet/lnet/peer.c b/lnet/lnet/peer.c
index f58e0e0..2ae8956 100644 (file)
--- a/lnet/lnet/peer.c
+++ b/lnet/lnet/peer.c
@@ -1148,6 +1148,35 @@ lnet_peer_primary_nid_locked(lnet_nid_t nid)
        return primary_nid;
 }
 
+bool
+lnet_is_discovery_disabled_locked(struct lnet_peer *lp)
+{
+       if (lnet_peer_discovery_disabled)
+               return true;
+
+       if (!(lp->lp_state & LNET_PEER_MULTI_RAIL) ||
+           (lp->lp_state & LNET_PEER_NO_DISCOVERY)) {
+               return true;
+       }
+
+       return false;
+}
+
+/*
+ * Peer Discovery
+ */
+bool
+lnet_is_discovery_disabled(struct lnet_peer *lp)
+{
+       bool rc = false;
+
+       spin_lock(&lp->lp_lock);
+       rc = lnet_is_discovery_disabled_locked(lp);
+       spin_unlock(&lp->lp_lock);
+
+       return rc;
+}
+
 lnet_nid_t
 LNetPrimaryNID(lnet_nid_t nid)
 {
@@ -1164,11 +1193,16 @@ LNetPrimaryNID(lnet_nid_t nid)
                goto out_unlock;
        }
        lp = lpni->lpni_peer_net->lpn_peer;
+
        while (!lnet_peer_is_uptodate(lp)) {
                rc = lnet_discover_peer_locked(lpni, cpt, true);
                if (rc)
                        goto out_decref;
                lp = lpni->lpni_peer_net->lpn_peer;
+
+               /* Only try once if discovery is disabled */
+               if (lnet_is_discovery_disabled(lp))
+                       break;
        }
        primary_nid = lp->lp_primary_nid;
 out_decref:
@@ -1796,35 +1830,6 @@ out_mutex_unlock:
 }
 
 bool
-lnet_is_discovery_disabled_locked(struct lnet_peer *lp)
-{
-       if (lnet_peer_discovery_disabled)
-               return true;
-
-       if (!(lp->lp_state & LNET_PEER_MULTI_RAIL) ||
-           (lp->lp_state & LNET_PEER_NO_DISCOVERY)) {
-               return true;
-       }
-
-       return false;
-}
-
-/*
- * Peer Discovery
- */
-bool
-lnet_is_discovery_disabled(struct lnet_peer *lp)
-{
-       bool rc = false;
-
-       spin_lock(&lp->lp_lock);
-       rc = lnet_is_discovery_disabled_locked(lp);
-       spin_unlock(&lp->lp_lock);
-
-       return rc;
-}
-
-bool
 lnet_peer_gw_discovery(struct lnet_peer *lp)
 {
        bool rc = false;
@@ -2168,8 +2173,6 @@ again:
                        break;
                lnet_peer_queue_for_discovery(lp);
 
-               if (lnet_is_discovery_disabled(lp))
-                       break;
                /*
                 * if caller requested a non-blocking operation then
                 * return immediately. Once discovery is complete then the
@@ -2187,6 +2190,16 @@ again:
                lnet_peer_decref_locked(lp);
                /* Peer may have changed */
                lp = lpni->lpni_peer_net->lpn_peer;
+
+               /*
+                * Wait for discovery to complete, but don't repeat if
+                * discovery is disabled. This is done to ensure we can
+                * use discovery as a standard ping as well for backwards
+                * compatibility with routers which do not have discovery
+                * or have discovery disabled
+                */
+               if (lnet_is_discovery_disabled(lp))
+                       break;
        }
        finish_wait(&lp->lp_dc_waitq, &wait);