tests/shell: cleanup creating dummy interfaces in tests

In "tests/shell/testcases/chains/netdev_chain_0", calling "trap ...
EXIT" multiple times does not work. Fix it, by calling one cleanup
function.

Note that we run in separate namespaces, so the cleanup is usually not
necessary. Still do it, we might want to run without unshare (via
NFT_TEST_UNSHARE_CMD=""). Without unshare, it's important that the
cleanup always works. In practice it might not, for example, "trap ...
EXIT" does not run for SIGTERM. A leaked interface might break the
follow up test and tests interfere with each other.

Try to workaround that by first trying to delete the interface.

Also failures to create the interfaces are not considered fatal. I don't
understand under what circumstances this might fail, note that there are
other tests that create dummy interface and don't "exit 77" on failure.
We want to know when something odd is going on.

Signed-off-by: Thomas Haller <thaller@redhat.com>
Signed-off-by: Florian Westphal <fw@strlen.de>

2 files changed, 10 insertions, 19 deletions

diff --git a/tests/shell/testcases/chains/dumps/netdev_chain_0.nft b/tests/shell/testcases/chains/dumps/netdev_chain_0.nft
index bc02dc18..aa571e00 100644
--- a/tests/shell/testcases/chains/dumps/netdev_chain_0.nft
+++ b/tests/shell/testcases/chains/dumps/netdev_chain_0.nft
@@ -1,5 +1,2 @@
 table netdev x {
-	chain y {
-		type filter hook ingress devices = { d0, d1 } priority filter; policy accept;
-	}
 }
diff --git a/tests/shell/testcases/chains/netdev_chain_0 b/tests/shell/testcases/chains/netdev_chain_0
index 41e72441..88bbc437 100755
--- a/tests/shell/testcases/chains/netdev_chain_0
+++ b/tests/shell/testcases/chains/netdev_chain_0
@@ -1,24 +1,18 @@
 #!/bin/bash
 
-ip link add d0 type dummy || {
-        echo "Skipping, no dummy interface available"
-        exit 77
-}
-trap "ip link del d0" EXIT
-
-ip link add d1 type dummy || {
-        echo "Skipping, no dummy interface available"
-        exit 77
-}
-trap "ip link del d1" EXIT
+set -e
 
-ip link add d2 type dummy || {
-        echo "Skipping, no dummy interface available"
-        exit 77
+iface_cleanup() {
+	ip link del d0 &>/dev/null || :
+	ip link del d1 &>/dev/null || :
+	ip link del d2 &>/dev/null || :
 }
-trap "ip link del d2" EXIT
+trap 'iface_cleanup' EXIT
+iface_cleanup
 
-set -e
+ip link add d0 type dummy
+ip link add d1 type dummy
+ip link add d2 type dummy
 
 RULESET="table netdev x {
 	chain y {