librdmacm: Fix rdma_resolve_addrinfo() deadlock in sync mode

Fix the issue that rdma_resolve_addrinfo() gets deadlock when run in
sync mode:
 (gdb) bt
 #0  futex_wait
 linux-rdma#1  __GI___lll_lock_wait
 linux-rdma#2  0x00007ffff7dae791 in lll_mutex_lock_optimized
 linux-rdma#3  ___pthread_mutex_lock
 linux-rdma#4  0x00007ffff7f9f018 in ucma_process_addrinfo_resolved
 linux-rdma#5  0x00007ffff7fa1447 in rdma_get_cm_event
 linux-rdma#6  0x00007ffff7fa1fef in ucma_complete
 linux-rdma#7  0x00007ffff7fa2f9c in resolve_ai_sa
 linux-rdma#8  0x00007ffff7fa36ab in __rdma_resolve_addrinfo
 linux-rdma#9  rdma_resolve_addrinfo
 linux-rdma#10 0x00000000004017b6 in start_cm_client_sync
 linux-rdma#11 0x00000000004018ee in main

Fixes: 7b1a686 ("librdmacm: Provide interfaces to resolve IB services")
Signed-off-by: Mark Zhang <[email protected]>
Signed-off-by: Sean Hefty <[email protected]>
Signed-off-by: Leon Romanovsky <[email protected]>

Author: MarkZhang81

librdmacm/cma.c

@@ -3217,17 +3217,16 @@ int rdma_resolve_addrinfo(struct rdma_cm_id *id, const char *node,
 		return ERR(EBUSY);
 	}
 
-	ret = __rdma_resolve_addrinfo(id_priv, node, service, hints);
-	if (ret)
-		goto fail;
-
 	id_priv->resolving_ai = true;
 	pthread_mutex_unlock(&id_priv->mut);
-	return 0;
 
-fail:
-	pthread_mutex_unlock(&id_priv->mut);
-	return ERR(ret);
+	ret = __rdma_resolve_addrinfo(id_priv, node, service, hints);
+	if (ret) {
+		id_priv->resolving_ai = false;
+		return ERR(ret);
+	}
+
+	return 0;
 }
 
 int rdma_query_addrinfo(struct rdma_cm_id *id, struct rdma_addrinfo **info)