From 25b47758b748dbc0afaaa96d5bfd72e3c4cc7c67 Mon Sep 17 00:00:00 2001
From: Christian Prochaska <christian.prochaska@genode-labs.com>
Date: Tue, 26 Jun 2018 12:01:44 +0200
Subject: [PATCH] linux: new slots for non-existent capabilities only

Prevent allocation of new cap-space slots each time a capability is
received by checking if the received capability already exists.

Fixes #2885
---
 repos/base-linux/src/lib/base/ipc.cc | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/repos/base-linux/src/lib/base/ipc.cc b/repos/base-linux/src/lib/base/ipc.cc
index 0ababee1e..2ab0d75b0 100644
--- a/repos/base-linux/src/lib/base/ipc.cc
+++ b/repos/base-linux/src/lib/base/ipc.cc
@@ -301,8 +301,20 @@ static void extract_sds_from_message(unsigned start_index,
 
 		int const associated_sd = Genode::ep_sd_registry()->try_associate(sd, id);
 
-		buf.insert(Capability_space::import(Rpc_destination(associated_sd),
-		                                    Rpc_obj_key(badge)));
+		Native_capability arg_cap = Capability_space::lookup(Rpc_obj_key(badge));
+
+		if (arg_cap.valid()) {
+
+			/*
+			 * Discard the received selector and keep using the already
+			 * present one.
+			 */
+
+			buf.insert(arg_cap);
+		} else {
+			buf.insert(Capability_space::import(Rpc_destination(associated_sd),
+			                                    Rpc_obj_key(badge)));
+		}
 
 		if ((associated_sd >= 0) && (associated_sd != sd)) {