[PATCH net-next 5/5] selftest: extend test_rss_context_queue_reconfigure for action addition

[<edward.cree@amd.com>]

From: Edward Cree <ecree.xilinx@gmail.com>

The combination of ntuple action (ring_cookie) and RSS context can
 cause an ntuple rule to target a higher queue than appears in any
 RSS indirection table or directly in the ntuple rule, since the two
 numbers are added together.  Verify the logic that prevents reducing
 the queue count in this case.

Signed-off-by: Edward Cree <ecree.xilinx@gmail.com>
---
I'm not able to run this selftest myself, because sfc doesn't support
ethtool set-channels (-L).  If someone else can verify that it works
on their hardware that would be much appreciated.

 .../selftests/drivers/net/hw/rss_ctx.py       | 26 +++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/tools/testing/selftests/drivers/net/hw/rss_ctx.py b/tools/testing/selftests/drivers/net/hw/rss_ctx.py
index 8f62dc29bd26..0b49ce7ae678 100755
--- a/tools/testing/selftests/drivers/net/hw/rss_ctx.py
+++ b/tools/testing/selftests/drivers/net/hw/rss_ctx.py
@@ -238,6 +238,32 @@ def test_rss_queue_reconfigure(cfg, main_ctx=True):
     else:
         raise Exception(f"Driver didn't prevent us from deactivating a used queue (context {ctx_id})")
 
+    if not main_ctx:
+        ethtool(f"-L {cfg.ifname} combined 4")
+        flow = f"flow-type tcp{cfg.addr_ipver} dst-ip {cfg.addr} dst-port {port} context {ctx_id} action 1"
+        try:
+            # this targets queue 4, which doesn't exist
+            ntuple2 = ethtool_create(cfg, "-N", flow)
+        except CmdExitFailure:
+            pass
+        else:
+            raise Exception(f"Driver didn't prevent us from targeting a nonexistent queue (context {ctx_id})")
+        # change the table to target queues 0 and 2
+        ethtool(f"-X {cfg.ifname} {ctx_ref} weight 1 0 1 0")
+        # ntuple rule therefore targets queues 1 and 3
+        ntuple2 = ethtool_create(cfg, "-N", flow)
+        # should replace existing filter
+        ksft_eq(ntuple, ntuple2)
+        _send_traffic_check(cfg, port, ctx_ref, { 'target': (1, 3),
+                                                  'noise' : (0, 2) })
+        # Setting queue count to 3 should fail, queue 3 is used
+        try:
+            ethtool(f"-L {cfg.ifname} combined 3")
+        except CmdExitFailure:
+            pass
+        else:
+            raise Exception(f"Driver didn't prevent us from deactivating a used queue (context {ctx_id})")
+
 
 def test_rss_resize(cfg):
     """Test resizing of the RSS table.